Re: filmscanners: Pixels per inch vs DPI
SKID Photography wrote: Try taking 3 different photos (Poaloids will do), at a 60th, 125th and 250th of a second. Will will see that there will be a significant exposrue difference between them. As far as 'spec' go, this would not b the first time that manufacturers fudged them. Harvey Ferdscneider partner, SKID Photography, NYC Are the faster shutter speed images in each case darker from the slower in your experience? If the factor is the flash, as you suggest, wouldn't that mean the duration is more in the order of 1/60th to 1/125th of a second or so, or that the output is otherwise being affected by the shutter speed timing/synching or whathaveyou? This seems like a very great discrepancy from the specs. Since I do very little studio flash photography, preferring to work with static lighting for studio work, I've never tested my flashes under conditions which were well enough controlled to know for sure what is going on. I'd be interested in anyone else who has done controlled studio testing using on camera electronic flashes, because if indeed the units are so mis-speced, I think the manufacturers should be confronted with this. Art
Re: filmscanners: Pixels per inch vs DPI
Arthur Entlich wrote: SKID Photography wrote: Try taking 3 different photos (Poaloids will do), at a 60th, 125th and 250th of a second. Will will see that there will be a significant exposrue difference between them. As far as 'spec' go, this would not b the first time that manufacturers fudged them. Harvey Ferdscneider partner, SKID Photography, NYC Are the faster shutter speed images in each case darker from the slower in your experience? Yes If the factor is the flash, as you suggest, wouldn't that mean the duration is more in the order of 1/60th to 1/125th of a second or so, or that the output is otherwise being affected by the shutter speed timing/synching or whathaveyou? Yes, this is what I have been saying. This seems like a very great discrepancy from the specs. Since I do very little studio flash photography, preferring to work with static lighting for studio work, I've never tested my flashes under conditions which were well enough controlled to know for sure what is going on. It is possible, with a dedicated camera/flash ttl auto thyristor system, that the flash unit will compensate for the faster shutter speeds with more power output. With a studio flash you can just use a flash meter and measure the difference in light capture at different shutter speeds. Harvey Ferdschneider partner, SKID Photography, NYC
Re: filmscanners: Pixels per inch vs DPI
B.Rumary wrote: Austin Franklin wrote: As many people probably realize, in a typical rear curtain/focal plane film cameras (as most 35mm SLRs are), any shutter speed beyond the maximum flash synch shutter speed exposes the film via a moving slit opening between the shutter curtains. I know what you say CAN be certainly true for the highest speeds of some cameras, but I did not know it was specifically related to the synch speed...I believe it's more related to shutter design than specifically tied to sync speed. Would you mind citing a source for that information? That is certainly not the case with vertical shutters, which all but one of my 35mm cameras have (Contaxes and Nikons), the exception being my Leica M. It _is_ related to the synch speed, because electronic flash is so fast that it needs the entire image area exposed when the flash goes off. If the camera speed is set above the synch speed, then the moving slit effect means that only that portion of the film exposed by the slit at the moment of flash will get the benefits of the flash. The flash-lighted area will then be correctly exposed, while the non-lit area will be heavily under-exposed. Note this only applies to electronic flash guns, which give very short duration flashes - typically 1/30,000 sec. The old fashioned flash bulbs burn much more slowly and give light for long enough for the slit to do it's full run across the film. I think you will find that very few, if any, flashes are of such a short duration. It has been my experience that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic flash will yield very different film exposures, no matter what type of shutter you are using. Harvey Ferdschneiderpartne partner, SKID photography, NYC
Re: filmscanners: Pixels per inch vs DPI
Austin Franklin wrote: As many people probably realize, in a typical rear curtain/focal plane film cameras (as most 35mm SLRs are), any shutter speed beyond the maximum flash synch shutter speed exposes the film via a moving slit opening between the shutter curtains. I know what you say CAN be certainly true for the highest speeds of some cameras, but I did not know it was specifically related to the synch speed...I believe it's more related to shutter design than specifically tied to sync speed. Would you mind citing a source for that information? That is certainly not the case with vertical shutters, which all but one of my 35mm cameras have (Contaxes and Nikons), the exception being my Leica M. As a result of the continuing and escalating acrimony between Austin and myself, and his incessant nitpicking of my postings, I do not intend to respond directly either publicly or privately to his postings in the future. I bring this to the attention of the other members so that you understand that my silence to Austin's challenges is not necessarily because I am unable to defend my position on either technical or other merits, but because I simply have decided his challenges are not worth my time to pursue. Further, the issue he has brought up to question above was an aside and tangential to the main point I was making in my post, that of the possibility of a design using one or more moving tri-line CCD arrays, across an aperture, if CCDs sampling response time was improved. However, since the question of why focal plane shutters have limited flash synch speeds might be of further interest to others, I provide the following expanded information for their edification. Austin, have a ball, nitpick at it as much as you like. Most camera mounted electronic flashes typically operate at between 1/1000th and 1/10-50,000 of a second, in fact most flashes operate in that range, or above, which is well above flash synch speeds on focal plane shutter cameras. The sequence of events is the shutter curtain opens fully, then sometime during the fully open shutter period, usually very nearly after the first shutter curtain is fully open, the flash goes off. With some flash systems you can adjust the flash to go off just before the second curtain starts closing, which can be useful for some effects involving movement. The limitation in flash synch speed is that the shutter opening has to be complete when the flash goes off, since the flash lighting only lasts a small fraction of the total exposure time. This is also why ghosting occurs when there is ambient light. In most cameras, including vertical shutters, once you get above the flash synch speed, there is either not enough time, or no time that the shutter curtain is fully open before the second shutter is beginning to follow. That is also why faster shutters can have faster flash synch speeds because they can have more open time before the shutter has to begin travel to close. As the shutter speed is increased, the opening between the first shutter curtain and the second decreases. So if a camera has a flash synch of 1/250 sec. and you try to use 1/500 sec, you will find that the flash will have gone off as the first curtain has fully opened, but by that time the second curtain will have already begun its travel, and you will get part of the frame missing flash lighting. There is probably one speed, or perhaps even two, above the flash synch speed where the shutter might actually be open fully, but it is too short a time to allow for the electronic flash to go off and finish its flash duration before the second curtain starts its movement. So, factually it might be possible that the shutter remains open fully on one or more further speeds beyond maximum flash synch, but not long enough to accomplish the necessary steps to complete a flash lighting before the second curtain begins its travel. I can think of no advantage for a camera to have a slower maximum flash synch speed offered than the shutter is capable of providing, so I can't see why any manufacturer would do so unless they manufactured a camera which had unreliable shutter travel. Art
Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
As a result of the continuing and escalating acrimony between Austin and myself, and his incessant nitpicking of my postings, I do not intend to respond directly either publicly or privately to his postings in the future. I bring this to the attention of the other members so that you understand that my silence to Austin's challenges is not necessarily because I am unable to defend my position on either technical or other merits, but because I simply have decided his challenges are not worth my time to pursue. Further, the issues he has brought up to question below were asides and tangential to the main points I was making in my post which were concerning the discussion comparing color dye clouds and capture of images digitally, not black and white developing, and my principle point was that grain was randomly distributed throughout the film emulsion and no process allowed for dye clouds to be moved or lined up within the emulsion during processing, and therefore there was also a built in error factor in grain/dye clouds as there is in digital imagine with its fixed pixels. As I also explained, the order of magnitude of error related to the size and density of grain versus pixels, and as pixels were made smaller and packed more densely, this error factor would lessen. Art Austin Franklin wrote: Austin Franklin wrote: Very simply, grain, or dye clouds are predetermined in their location and shape and are not relocated by picture content. What about development? Also, some developing techniques can somewhat alter the shape or size of the dye clouds... Somewhat? However, most of this type of thing is done in custom film development of black and white film, You can alter the grain of BW film by at least two to four times simply by developer choice, dilution, temperature and technique. It certainly isn't custom, most anyone who uses BW has their favorite developer/dilution/temperature and technique that suits their needs/style/experimentation. It is VERY critical when talking about film grain to discuss development AND even exposure (as you mentioned push/pull too)...since the same film can give such drastically different results...and more so even if you are using Zone system compensation development. because the need to control so many other variables within color film development doesn't allow for much playing around. Most color film processing is fairly uniform in its method... Not quite true...see below... This is why almost all color film is souped in one of two basic color chemistry types (C-41 or E-6). There are different E-6 and C-41 processes. Different chemical AND entirely different developments, as well as techniques. E6 can be 3 bath or 6 bath, and C-41 can be 2 bath or 3 bath. All of this plays a SIGNIFICANT role on the shape and size of the dye clouds. It can be far more significant than you made it out to be. However, I know of no color development technique that is capable of moving film grain or dye clouds within the emulsion so that they can line up the grain as a result of the image content. If you do, I'd like to here about it. I don't believe anyone ever suggested that at all... .
Re: filmscanners: Pixels per inch vs DPI
SKID Photography wrote: I think you will find that very few, if any, flashes are of such a short duration. It has been my experience that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic flash will yield very different film exposures, no matter what type of shutter you are using. Harvey Ferdschneiderpartne partner, SKID photography, NYC My Vivitar 285 flash indicates specifications of 1/1000th to 1/30,000 sec, but it is what, 20 years old? I couldn't find the specs of my much newer Nikon speedlite, but I think it has an even faster minimum speed. Art
Re: filmscanners: Pixels per inch vs DPI
Arthur Entlich wrote: SKID Photography wrote: I think you will find that very few, if any, flashes are of such a short duration. It has been my experience that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic flash will yield very different film exposures, no matter what type of shutter you are using. Harvey Ferdschneiderpartne partner, SKID photography, NYC My Vivitar 285 flash indicates specifications of 1/1000th to 1/30,000 sec, but it is what, 20 years old? I couldn't find the specs of my much newer Nikon speedlite, but I think it has an even faster minimum speed. Art Try taking 3 different photos (Poaloids will do), at a 60th, 125th and 250th of a second. Will will see that there will be a significant exposrue difference between them. As far as 'spec' go, this would not b the first time that manufacturers fudged them. Harvey Ferdscneider partner, SKID Photography, NYC
RE: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Further, the issues he has brought up to question below were asides and tangential to the main points I was making in my post which were concerning the discussion comparing color dye clouds and capture of images digitally, not black and white developing, I DID talk about color (see below), not BW exclusively. I find it funny that you ignore that fact. You really believe the size and shape of the film grain is tangential to the capture of images digitally? How do you arrive at that conclusion? and my principle point was that grain was randomly distributed throughout the film emulsion and no process allowed for dye clouds to be moved or lined up within the emulsion during processing, I do believe that is common knowledge, and I don't believe anyone disagreed with that. My correction to your statement was that development has a LOT to do with grain size. Austin Franklin wrote: Very simply, grain, or dye clouds are predetermined in their location and shape and are not relocated by picture content. What about development? Also, some developing techniques can somewhat alter the shape or size of the dye clouds... Somewhat? However, most of this type of thing is done in custom film development of black and white film, You can alter the grain of BW film by at least two to four times simply by developer choice, dilution, temperature and technique. It certainly isn't custom, most anyone who uses BW has their favorite developer/dilution/temperature and technique that suits their needs/style/experimentation. It is VERY critical when talking about film grain to discuss development AND even exposure (as you mentioned push/pull too)...since the same film can give such drastically different results...and more so even if you are using Zone system compensation development. because the need to control so many other variables within color film development doesn't allow for much playing around. Most color film processing is fairly uniform in its method... Not quite true...see below... This is why almost all color film is souped in one of two basic color chemistry types (C-41 or E-6). There are different E-6 and C-41 processes. Different chemical AND entirely different developments, as well as techniques. E6 can be 3 bath or 6 bath, and C-41 can be 2 bath or 3 bath. All of this plays a SIGNIFICANT role on the shape and size of the dye clouds. It can be far more significant than you made it out to be. However, I know of no color development technique that is capable of moving film grain or dye clouds within the emulsion so that they can line up the grain as a result of the image content. If you do, I'd like to here about it. I don't believe anyone ever suggested that at all...
RE: filmscanners: Pixels per inch vs DPI
As a result of the continuing and escalating acrimony between Austin and myself, and his incessant nitpicking of my postings, I either question you, or point out you're mistaken, missing something...whatever...and you call it nitpicking. This is entirely a cop-out, Arthur. If you were able to just stick to the technical merits of your arguments, there would be no problem. I do not intend to respond directly either publicly or privately to his postings in the future. I take that as positive, but be assured, I will respond to yours, if I feel the need to.
Re: filmscanners: Pixels per inch vs DPI
SKID Photography wrote: Arthur Entlich wrote: SKID Photography wrote: I think you will find that very few, if any, flashes are of such a short duration. It has been my experience that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic flash will yield very different film exposures, no matter what type of shutter you are using. Harvey Ferdschneiderpartne partner, SKID photography, NYC My Vivitar 285 flash indicates specifications of 1/1000th to 1/30,000 sec, but it is what, 20 years old? I couldn't find the specs of my much newer Nikon speedlite, but I think it has an even faster minimum speed. Art Try taking 3 different photos (Poaloids will do), at a 60th, 125th and 250th of a second. Will will see that there will be a significant exposrue difference between them. As far as 'spec' go, this would not b the first time that manufacturers fudged them. Harvey Ferdscneider partner, SKID Photography, NYC I apologize to all for my above postI was writing it as I was having my morning coffee, I hit the wrong key, and it went out before it was finished. :-( It should have read: Try taking 3 different photos (Polaroids will do), at a 60th, 125th and 250th of a second. Will will see that there will be a significant exposure differences between them (due to long flash durations). In fact, usually, the less expensive flashes will have longer durations than the better ones. Which is to say that they get they power by flash duration rather than initial power. As far as 'specs' go, this would not be the first time that manufacturers have fudged them. Again, sorry about the mis-post. Harvey Ferdschneider partner, SKID Photography, NYC
Re: filmscanners: Pixels per inch vs DPI
Harvey, Sorry for the stupid question, but have you done this test in an effectively dark room? Perhaps you're seeing ambient light begin to contribute to exposure? For ambient light not to have any effect on exposure it should be at least 5 stops below the working setting. I thought the longest flash durations were in the neighborhood of 1/500th sec. I don't recall seeing exposure differences at shutter speeds 1/250 or slower where ambient light isn't a factor. Dave - Original Message - From: SKID Photography [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Wednesday, October 31, 2001 3:26 AM Subject: Re: filmscanners: Pixels per inch vs DPI B.Rumary wrote: Austin Franklin wrote: As many people probably realize, in a typical rear curtain/focal plane film cameras (as most 35mm SLRs are), any shutter speed beyond the maximum flash synch shutter speed exposes the film via a moving slit opening between the shutter curtains. I know what you say CAN be certainly true for the highest speeds of some cameras, but I did not know it was specifically related to the synch speed...I believe it's more related to shutter design than specifically tied to sync speed. Would you mind citing a source for that information? That is certainly not the case with vertical shutters, which all but one of my 35mm cameras have (Contaxes and Nikons), the exception being my Leica M. It _is_ related to the synch speed, because electronic flash is so fast that it needs the entire image area exposed when the flash goes off. If the camera speed is set above the synch speed, then the moving slit effect means that only that portion of the film exposed by the slit at the moment of flash will get the benefits of the flash. The flash-lighted area will then be correctly exposed, while the non-lit area will be heavily under-exposed. Note this only applies to electronic flash guns, which give very short duration flashes - typically 1/30,000 sec. The old fashioned flash bulbs burn much more slowly and give light for long enough for the slit to do it's full run across the film. I think you will find that very few, if any, flashes are of such a short duration. It has been my experience that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic flash will yield very different film exposures, no matter what type of shutter you are using. Harvey Ferdschneiderpartne partner, SKID photography, NYC
Re: filmscanners: Pixels per inch vs DPI
Oh yes, we always check ambient to flash ratios when we shoot. We do tend to do a lot of mixing of lights in our celebrity portraiture, so I'm well aware of the 5 stop increment. On the other hand, we have been doing a lot of shooting (with studio strobes) at 1/500th of a second recently, and maybe my memory has been colored by the even greater loss of effective flash power with the extremely fast shutter speeds of late. But again, don't go by what the manufacturers spec, try it yourself and see. We are photographing 'The Chemical Brothers' this weekend for a magazine shoot, and if time permits, I will try to run a series of Polaroids, again, to double check my understanding. Harvey Ferdschneider partner, SKID photography, NYC Dave King wrote: Harvey, Sorry for the stupid question, but have you done this test in an "effectively" dark room? Perhaps you're seeing ambient light begin to contribute to exposure? For ambient light not to have any effect on exposure it should be at least 5 stops below the working setting. I thought the longest flash durations were in the neighborhood of 1/500th sec. I don't recall seeing exposure differences at shutter speeds 1/250 or slower where ambient light isn't a factor. Dave - Original Message - From: SKID Photography [EMAIL PROTECTED]> To: [EMAIL PROTECTED]> Sent: Wednesday, October 31, 2001 3:26 AM Subject: Re: filmscanners: Pixels per inch vs DPI > "B.Rumary" wrote: > > > Austin Franklin wrote: > > > > As many people probably realize, in a typical rear curtain/focal plane > > > > film cameras (as most 35mm SLRs are), any shutter speed beyond the > > > > maximum flash synch shutter speed exposes the film via a moving slit > > > > opening between the shutter curtains. > > > > > > I know what you say CAN be certainly true for the highest speeds of some > > > cameras, but I did not know it was specifically related to the synch > > > speed...I believe it's more related to shutter design than specifically tied > > > to sync speed. Would you mind citing a source for that information? > > > > > > That is certainly not the case with vertical shutters, which all but one of > > > my 35mm cameras have (Contaxes and Nikons), the exception being my Leica M. > > > > > It _is_ related to the synch speed, because electronic flash is so fast that > > it needs the entire image area exposed when the flash goes off. If the camera > > speed is set above the synch speed, then the "moving slit" effect means that > > only that portion of the film exposed by the "slit" at the moment of flash > > will get the benefits of the flash. The "flash-lighted" area will then be > > correctly exposed, while the non-lit area will be heavily under-exposed. > > > > Note this only applies to electronic flash guns, which give very short > > duration flashes - typically 1/30,000 sec. The old fashioned flash bulbs > > "burn" much more slowly and give light for long enough for the "slit" to do > > it's full run across the film. > > I think you will find that very few, if any, flashes are of such a short duration. It has been my experience > that the difference between, a 250th, 125th and 60th of a second exposure and almost any brand electronic > flash will yield very different film exposures, no matter what type of shutter you are using. > > > Harvey Ferdschneiderpartne > partner, SKID photography, NYC > > > >
RE: filmscanners: Pixels per inch vs DPI
I thought the longest flash durations were in the neighborhood of 1/500th sec. I don't recall seeing exposure differences at shutter speeds 1/250 or slower where ambient light isn't a factor. It takes some time for the flash to actually fire...and I would also guess different types of flashes have different timing (latency). Does anyone actually know what a typical flashes latency time is? I can check my Elinchroms to see what they say this time is supposed to be...as I have the service manuals for them, and they are pretty comprehensive...hopefully, they'll have something to say about it.
Re: filmscanners: Pixels per inch vs DPI
Fast sync speeds being desirable, maximum sync in any particular design is determined by that fastest speed where entire frame is still open at once. Another one that doesn't require an engineering degree to understand:) Dave - Original Message - From: Austin Franklin [EMAIL PROTECTED] As many people probably realize, in a typical rear curtain/focal plane film cameras (as most 35mm SLRs are), any shutter speed beyond the maximum flash synch shutter speed exposes the film via a moving slit opening between the shutter curtains. I know what you say CAN be certainly true for the highest speeds of some cameras, but I did not know it was specifically related to the synch speed...I believe it's more related to shutter design than specifically tied to sync speed. Would you mind citing a source for that information? That is certainly not the case with vertical shutters, which all but one of my 35mm cameras have (Contaxes and Nikons), the exception being my Leica M.
RE: filmscanners: Pixels per inch vs DPI
Fast sync speeds being desirable, maximum sync in any particular design is determined by that fastest speed where entire frame is still open at once. Another one that doesn't require an engineering degree to understand:) In simple terms, yes...the concept IS simple...but there may be other factors involved (such as the mechanical timing of the sync closure, latency, and possibly tolerance), which is what I am asking. It may be that the next speed up from synch is also fully open. Shutter speeds can be quite off from what they are labeled...so to allow margins, the next speed down from one that is fully open may be the one they use for max sync speed, possibly to assure reliability.
Re: filmscanners: Pixels per inch vs DPI
Margins are cool. - Original Message - From: Austin Franklin [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, October 30, 2001 9:45 PM Subject: RE: filmscanners: Pixels per inch vs DPI Fast sync speeds being desirable, maximum sync in any particular design is determined by that fastest speed where entire frame is still open at once. Another one that doesn't require an engineering degree to understand:) In simple terms, yes...the concept IS simple...but there may be other factors involved (such as the mechanical timing of the sync closure, latency, and possibly tolerance), which is what I am asking. It may be that the next speed up from synch is also fully open. Shutter speeds can be quite off from what they are labeled...so to allow margins, the next speed down from one that is fully open may be the one they use for max sync speed, possibly to assure reliability.
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin, you criticise Art, then do it yourself..? How's about we all try to attack the ball, not the man.. Woah, Mark...where did I make a personal attack on Rob? I DID stick to the ball...please point it out...I am interested. At 11:31 AM 28/10/01 -0500, you wrote: .. I don't think there's any point in my responding to an argument like this. That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. No, it's not 'just the way it is'. There are five incremented integers between 4 and 9, and the term 'larger' than is NOT ambiguous.. :-) But why IS 9 larger than 4? You didn't explain why. Saying a dye cloud has more information content than A pixel is NOT ambiguous at all, it's just a fact...and for the same reason why 9 is more than, say, 1. Rob's question of how a dye cloud can contain more information than a pixel still stands.. Use your engineering skill and draw a picture! I'm certainly interested. I believe I've explained this about as thoroughly as I can, without holding a class... It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud. That's not what was being asked. You left out 'pixel of the same or smaller size'. I didn't leave anything out...it doesn't matter WHAT size pixel, a pixel is but a single value of tonality, period. A pixel does NOT contain the same amount of information as A dye cloud. As I said, dye clouds are variable in shape, and a pixel is only a square (or some fixed shape), and the data in A pixel (he said A) does not represent this shape. Rob also raised the perfectly valid point of the rapid development in the number/size of detectors and the amount of color info they can detect. Are you suggesting that dye clouds are so small, ie molecular or atomic :-), that there is no way to create a detector that small? I said that physical limitations prohibit sensors from being as small as dye clouds. AS I said, these sensors have to get light to them, and they have to have wires in and out of them, as well as these wires require some level of separation due to noise. I also said that the consumer digital cameras that have sensors of the same resolution, but the sensor arrays are smaller in size, and give a worse image, for the noise reason, than say a D-30 with a larger sensor and same (if not less) resolution.
RE: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Thanks Harvey...but I really don't know what more I can explain...and I don't know how much more basic I can get... Sigh. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of SKID Photography Sent: Sunday, October 28, 2001 11:14 PM To: [EMAIL PROTECTED] Subject: Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI Austin, Most of what you are saying in this latest missive was brought up before and rejected by Rob. It was at that point that I gave up. But, kudos to you for your tenacity and deep knowledge on this subject. I feel like I've been vindicated, and by someone with far more skill than I. Harvey Ferdschneider partner, SKID Photography, NYC Austin Franklin wrote: Austin wrote: That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud. I suspected I should have chosen a word other than argument. The number 9 is larger than the number 4 because it is a convention that 9 is 5 integer values larger than 4. Other than that, the digit 9 or the word nine are simply labels to represent an idea. Saying it is because it is does not constitute any sort of meaningful explanation. Some things just are, and the truth is manifested in and of it self. A basket that has 25 eggs in it has MORE eggs than a basket with 4, right? All semantics aside. Here is (one of) your original question(s)/statement(s), which I have been answering: I don't see why stochastic or random dye clouds inherently provides more information than a pixel. The point of contention appears to be more information. I believe we agree on what more and information mean. Pixels ONLY represent the tonal value of the area which the sensor sees, which does NOT represent the physical characteristics of the dye cloud, unless the dye cloud is perfectly square and happens to line up perfectly in the field of view of that one pixel. In fact a pixel MAY represent many dye clouds, or only a portion of a single dye cloud, but there is NO way you can represent the amount of information in a single dye cloud by a single pixel, when A pixel ONLY contains tonal information. Dye clouds are irregular in shape, and dye clouds do NOT line up 1:1 with pixels. Even if you did characterize each and every dye cloud digitally, you would need more than spot tonal information, You would also have to use many pixels, or characterize the shape, because it's irregular. Characterizing the shape will be very consuming (as in a lot of data) to represent. Given all that, I believe it is obvious why a dye cloud provides inherently more information than a pixel. If you don't see that, I can't explain it any further without sitting down at a white board and drawing it out step by step... Claiming that a pixel has anything to do with physics is an odd thing to do. Now that's an odd thing to do...claim a pixel has nothing to do with physics... I don't know about your scanner, but mine is not Gnostic. A pixel is a number or a set of numbers that represent a mixture and intensity of light. It's not limited by physics. A pixel has an analog to digital origin in our case. This analog to digital conversion has limitations, which ARE limitations of physics. That's just a fact. If you created a drawing with Adobe Illustrator, then your pixels would not have an analog origin. A dye cloud has a certain dimension and a certain behviour with light. A pixel is not limited in the same way. Er, a pixel is FAR more limited, since it is only representing a single characteristic of a regular patterned point source (as in a single element in a regular grid pattern of equal sized elements). A pixel could represent an area the size of an atom, or the size of a galaxy; *any* dimension Except for the fact that we are talking about film scanners, and the are a pixel can represent is limited by physics... and it may be an 8 bit number or you could pick any number of bits. Yes, and it ONLY represents tonality, NO other characteristic at all is represented by a pixel. How small would you like to make the area represented by the pixel and how many bits of RGB would you like to use until you exceed the data contained in a chemical representation of an image? Then you said it's just a matter of increasing the resolution of the grid... Which is where the physical characteristics come in play. There are physical limitations as to how many pixels you can practically use in a scanning system. You can't just make a sensor of infinite density (or infinite size and use optics
Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Dye clouds are a double edged sword. On the one hand, due to the random positioning and their transparent nature, they can make for a very small apparent resolution because they can overlap in all sorts of random patterns making areas much smaller than a fixed array of pixels which would read the R G B or C M Y components of the pixel area within the same area (the sensor reads all three color separations from the same locations). A single cyan dye cloud, for instance, might partially overlap with a magenta one in one area, a yellow in another and perhaps both or none in yet another. Defining all of this via a pixel array would require very, very, small pixels. Dye clouds, however, being randomly positioned and shaped allow for all sorts of irregular information to form, much of which is smaller than one dye cloud itself, although it may also not be accurate in either color or location. In this case, the grain or dye clouds contain a certain level noise (errors), but when it gets that small, our eye would rather see randomized, inaccurate information than non-random, geometric forms or total lack of this filler. Dye clouds are, in effect, positioned at the point of manufacture, when their progenitor (a silver grain) is laid down in the specific color emulsion layer, long before anyone knows the image content. The grain that eventually allows for the creation of the dye cloud in color films is completely randomized in it's position and to a lesser extent, its shape, and within manufacturing limits, its size. The only reason any specific shaped and positioned dye cloud does not become an impediment or degrade the image characteristic is because each are so small and jumbled around, so in most cases, one rarely can one see an individual dye cloud. They are very small, and are clumped with parts of other dye clouds, both of the same color, and because of their transparency, other emulsion layers which contain other colored dye clouds. Now, if some brilliant engineer (is that an oxymoron? (that's a joke!)) figures out a way to allow for silver grains to literally migrate within the emulsion or change shape as the image is formed or during development and do nice things like, say, all line up perfectly when I'm taking a picture of something with a straight line, well then, yes, the dye clouds will have something going for them that would not theoretically be possible even with very tiny pixels (however, I actually imagine those brilliant engineers will come up with a way to make pixels mobile before making grain do so ;-)... Very simply, grain, or dye clouds are predetermined in their location and shape and are not relocated by picture content. Pixels would be required to be very small to reproduce the perception of current film technologies. Fuji has a hexagonal/star shaped pixel array, so that might reduce the rectangular elements, but we still are faced with the fact that the red, green and blue separations are all taken from an identically positioned array. As to the future of digital capture technologies, who knows what might be stumbled upon. Both film and pixel based captures have inherent errors built into the process, and for now pixel based have many more limitations, but that could change. Art
Re: filmscanners: Re: filmscanners: Pixels per inch vs DPI
Thanks, It would appear the C70 hasn't made it over the great water yet. It does look like a less expensive version of the C80. Hope it comes our way soon. Art Rob Geraghty wrote: Is the C70 being sold anywhere around the world now? http://www.epson.com.au/products/home_and_office/C70.html Yes. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com .
Re: filmscanners: Re: filmscanners: Pixels per inch vs DPI
I see you folks recommending these other Epsons a lot, that aren't advertised with the six color photo printing.Is there any real advantage to going with something like the 890 or 1280 over one of the less expensive office color inkjets? I'm using a HP 722C right now, and I actually get pretty good results from it, although it's only 300dpi. I would like whatever I get next to be a significant improvement. Do I need to go all the way with Epson to get that? Ken
Re: filmscanners: Pixels per inch vs DPI
From: Austin Franklin [EMAIL PROTECTED] I didn't leave anything out...it doesn't matter WHAT size pixel, a pixel is but a single value of tonality, period. A pixel does NOT contain the same amount of information as A dye cloud. As I said, dye clouds are variable in shape, and a pixel is only a square (or some fixed shape), and the data in A pixel (he said A) does not represent this shape. I dare say an individual dye cloud varies in tone as well as shape, if not color as well. There are contaminants you know. There is obviously no way one pixel could represent an individual dye cloud with complete accuracy. One need not be an engineer to understand this:) A more interesting question (to me) would be how many pixels are needed to do the job (per cloud, of course). Then we would know the answer to the question, how many angels can dance on a pixel describing the head of a needle in the haystack that's lost in the clouds bg Dave
Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin, I personally have really enjoyed and learned a lot from your last several posts (after my last post) and I suspect that there comes a point where one has to realize that unfortunately, with some people, 'you can lead a horse to water...' Harvey Ferdschneider partner, SKID Photography, NYC Austin Franklin wrote: Thanks Harvey...but I really don't know what more I can explain...and I don't know how much more basic I can get... Sigh. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of SKID Photography Sent: Sunday, October 28, 2001 11:14 PM To: [EMAIL PROTECTED] Subject: Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI Austin, Most of what you are saying in this latest missive was brought up before and rejected by Rob. It was at that point that I gave up. But, kudos to you for your tenacity and deep knowledge on this subject. I feel like I've been vindicated, and by someone with far more skill than I. Harvey Ferdschneider partner, SKID Photography, NYC
RE: filmscanners: Pixels per inch vs DPI
From: Austin Franklin [EMAIL PROTECTED] I didn't leave anything out...it doesn't matter WHAT size pixel, a pixel is but a single value of tonality, period. A pixel does NOT contain the same amount of information as A dye cloud. As I said, dye clouds are variable in shape, and a pixel is only a square (or some fixed shape), and the data in A pixel (he said A) does not represent this shape. I dare say an individual dye cloud varies in tone as well as shape, if not color as well. Yes, that is very true... There are contaminants you know. There is obviously no way one pixel could represent an individual dye cloud with complete accuracy. One need not be an engineer to understand this:) Glad to hear that ;-) A more interesting question (to me) would be how many pixels are needed to do the job (per cloud, of course). That number varies a LOT (dye cloud size varies a lot too)...you can always sample analog at higher and higher frequencies (as in line pair per mm), but there is a point where the data really isn't useful...at least in a lot of instances. Assuming a 3 micron spot size... A micron is one millionth of a meter, and a meter is 39.37...so 3 microns is 0.00011811 inches. (39.37 * .01 * 3)...which is 8,466/inch... A 35mm sensor is, say, 24 x 36, or 1 x 1.5...and you need 2x to sample, so 1 x 8,466/inch x 1.5 x 8,466/inch = 108M spots BUT...camera sensors need (three) four sensors (RGBG, extra G for contrast) for every pixel, since a single sensor can only capture one color...so that comes out to 324M sensors to capture the same information (to some degree) as does a 35mm color film with 3u spot size... Note, when a digital camera claims 6M pixels...that's in fact a flat out lie. It is REALLY 1.5M pixels, with four sensors per pixel...a pixel IS made up of all three RGB components, so it is really misleading to make the claims they do. They would be more honest to call it a 6M SENSOR array. How they get 6M pixel OUTPUT is interpolation...which, of course, means that %75 of the image data is just made up, and not real image data (to a large degree). And you thought the scanner dynamic range issue was misleading... And, because you need four sensors to sample one spot of the same size, the sensors would have to be 1.5u x 1.5u in size. Now, let's take this from another standpoint...film resolution. Let's assume 200lp/mm (which Royal Gold 25 does). That's 400 lines/mm (a line pair is two lines, one black and one white). 25.4 mm per inch, so 25.4 mm/inch x 400 lines/mm = 10,160 lines/inch. 1 x 10,160 x 1.5 x 10,160 = 155M spots...but then multiply by 4 because you need four sensors to make one pixel...or 466M sensors... There are linear CCDs used in scanners, that are 10k samples across...but, they aren't 1 wide. The sensor area is more like 3 wide, and the fact that it's linear, means the wires have a LOT more area to come out of the sensor than in a packed array, and also a lot less distance to travel to get to the amplifiers. You really can't compare linear CCDs to one shot digital camera arrays, they are entirely different animals from a technology and packaging standpoint. All the above is purely to replicate with a digital sensor array, the same amount of information (to some degree) that film has. This is an entirely different problem than scanning film...since to scan film you need to scan at 2x the maximum frequency you want to capture, so you would multiply each dimension by 4...so to really scan every dye cloud on a 200lp/mm piece of 35mm film, you'd get a total of near 2G bytes when done!
Re: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote.. ..I DID stick to the ball...please point it out...I am interested. I'm away from my normal PC right now, so I can't quote the lines that I felt were getting personal (a convenient cop-out, I know!), but comments like this: '..but I really don't know what more I can explain...and I don't know how much more basic I can get... Sigh.' ..are a bit of a put-down in my book. Perhaps I am just the overly sensitive type, but I would be a bit offended if they were comments directed towards me. Anyway, back to the debate, which I hope isn't getting too off-topic.. But why IS 9 larger than 4? You didn't explain why. We have to some basic 'given's', otherwise nothing can be discussed... :-) Saying a dye cloud has more information content than A pixel is NOT ambiguous at all, it's just a fact.. Yes, agreed. But my (and I think Rob's) point is that fact is not of much importance unless you are heading for a useful conclusion, eg saying that 'electronic sensors will never give higher resolution than film.' There are many factors involved in that question, eg over what size area? (Why do we use 6x7 instead of 35mm? - Because of those darned too-big dye clouds, that's why!) And I'm concerned about recording the image, not dye clouds. In the same way that we use larger format films, and smaller dye-clouds as methods to get better images, we can keep reducing the size of the 'pixels', and if we meet a physics limit (or more often an expense limit), then we can increase the area over which that image is recorded. And that *doesn't* necessarily mean huge cameras/lenses, if you think laterally.. I said that physical limitations prohibit sensors from being as small as dye clouds. As above, this is only an issue if you are trying to match up your sensor with some pre-determined film size. AS I said, these sensors have to get light to them Which can be bent, magnified, reflected, spread... and they have to have wires in and out of them hmm. Maybe using current technology they do.. :-) Anyway, as soon as a decent *affordable* 8Mp or better digicam arrives, preferably with interchangable lenses and decent battery life, I'll be jumping ship and only dragging out the film scanner for the 'archives'.. I won't be pining for the days of dye-clouds.. mt This message was sent through MyMail http://www.mymail.com.au
Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin wrote: Very simply, grain, or dye clouds are predetermined in their location and shape and are not relocated by picture content. What about development? I could just answer this with an Austinism and say what about it?, but I'll afford you a little more respect than you hand out. Development obviously is where dye clouds are created from the photon activated silver grains. Depending if the film is a positive or negative type, those grains activated by photons either are used to create dye clouds or to be areas where dye clouds are ultimately removed via a bleaching process in creating the final processed film. Also, some developing techniques can somewhat alter the shape or size of the dye clouds, as the grain edges can be eaten away or softened by some developers or the dye cloud could be enlarged during the chemical reaction which creates it, and development could also theoretically alter what level of grain activation will develop into dye clouds by change of chemical concentration, temperature of the baths and timing. However, most of this type of thing is done in custom film development of black and white film, because the need to control so many other variables within color film development doesn't allow for much playing around. Most color film processing is fairly uniform in its method, assuming it is being done correctly (unfortunately, it often isn't controlled as well as it should be, which is evident by the number of people dealing with poor color processing). This is why almost all color film is souped in one of two basic color chemistry types (C-41 or E-6). It is true that some of the above mentioned grain alterations also occur during pushing of color films, but usually the intent of these processes is to extend film sensitivity more than to increase grain, for instance. Some photographers do pull some color films, which creates an apparent slower film and might reduce grain size in some cases. However, I know of no color development technique that is capable of moving film grain or dye clouds within the emulsion so that they can line up the grain as a result of the image content. If you do, I'd like to here about it. Art Austin Franklin wrote: Very simply, grain, or dye clouds are predetermined in their location and shape and are not relocated by picture content. What about development? .
Re: filmscanners: Re: filmscanners: Pixels per inch vs DPI
I think the model many of the major multinational high tech companies use is to get their RD money back first via selling to markets that are less price sensitive. Then they introduce the product into the US, pretty much paid for through other international sales, and can compete more easily in the very cutthroat price sensitive environment there. We get some advantage by this here in Canada, on some goods, but certainly not all. And importation can be quite daunting, due to exchange rates, taxes, shipping costs and possible loss of warranty. Art Rob Geraghty wrote: Arthur Entlich [EMAIL PROTECTED] wrote: Thanks, It would appear the C70 hasn't made it over the great water yet. It does look like a less expensive version of the C80. Hope it comes our way soon. I just wish I could buy printers at prices as cheap as in the US. I understand about discounts for bulk, but isn't it odd that Epson printers in the US are cheaper after a much longer voyage? :( Rob .
Re: filmscanners: Pixels per inch vs DPI
As many people probably realize, in a typical rear curtain/focal plane film cameras (as most 35mm SLRs are), any shutter speed beyond the maximum flash synch shutter speed exposes the film via a moving slit opening between the shutter curtains. If, at some later date, digital sensors can be made to respond and sample quickly enough, and the data stream could also be rapid enough, then perhaps a moving/sweeping sensor, similar to those used in some film scanners could be incorporated into a camera, so rather than having to use a sensor panel which has to cover the full dimensions of the area being captured, a simpler and denser populated tri-color line sensor would be adequate, or perhaps several of these sensors could each capture one portion of the image and then stitching it together. Art
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: How is a randomly sized and shaped dye cloud a useful characteristic of shape and position? How is it more useful than a precise position in an array? Because it is. It's the way the world works. It IS additional information, plain and simple. Usefulness is a completely different issue, but it is ALSO useful, to a point. I don't think there's any point in my responding to an argument like this. Rob
Re: filmscanners: Pixels per inch vs DPI
As usual, you've pulled another Austin. I'm going to take this step by step, so that you don't have the wriggle room that you usually try to create for yourself. I arrived in this discussion after you stated that in was not possible to get acceptable photo results from 100 dpi input, and I stated that the HP Photosmart printer used 100 to 150 dpi input on a 300 dpi output system which took advantage of an overprinting method which could supply several drops of ink to the same point on the paper. I stated that the Photosmart printer produced a reasonable quality result because of this feature and that I was familiar with this technology because I had discussions with the software engineers who wrote the drivers for this printer, and it was explained to me in some detail how the HP Photosmart system operated. You then went on to discuss Epson printers, which I was not talking about, and you stated the reason the colors were not placed upon each other was because the pigmented inks weren't transparent enough. So, I explained that the HP printers I was discussing used dye inks, (other HP consumer printers use dye inks but pigmented black, but their photo type printers use(d) only dye inks including the black) which made your point moot. It was made further moot because other than the printers I listed, inkjet printers don't use pigmented ink (other than the black used in some HP printers), (unless you buy third-party product), but in the usual fashion, which you always deny you do, you selectively quoted and misrepresented what I said by both taking my information out of context, AND addressing a secondary issue as if it was the point I was trying to make. Then again, what else is new? Art PS: I am still not convinced Epson printers do not print several ink colors on top of one another, regardless of your microscopic examination (yes, I do recall) especially the photo CcMmYK color models and the newer 2880 dpi variable dot types, but I wasn't addressing Epson printers as to whether they did or not. And since this is no longer relating to scanners, it will probably be my last word on this subject. Austin Franklin wrote: Others that use pigmented inks, although I wouldn't refer to them as consumer grade, are the Epson 5500, 7500 and 9500, some of the Rolands, and some other larger carriage printers. The other Epsons, including the 3000, and even the 870/890 1270/1290 use dyes, although the later were supposed to be specially designed for longer fade resistance than the average ones. The ink technology wasn't the issue, the issue was the Epson printers you mention do not place more than one drop of ink on any one spot...no matter what their ink technology is... .
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: How is a randomly sized and shaped dye cloud a useful characteristic of shape and position? How is it more useful than a precise position in an array? Because it is. It's the way the world works. It IS additional information, plain and simple. Usefulness is a completely different issue, but it is ALSO useful, to a point. I don't think there's any point in my responding to an argument like this. That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud.
RE: filmscanners: Pixels per inch vs DPI
As usual, you've pulled another Austin. Art, just because I have pointed out you don't know what you're talking about quite a few times, and the fact that you are NOT an engineer, but like to pretend you are, and that I sometimes disagree with your assessments of things, that is no reason to be such a twit. If you can't partake in a discussion by using real facts, and presenting lucid points, then please just sit on your hands and keep quiet. I'm going to take this step by step, so that you don't have the wriggle room that you usually try to create for yourself. I don't need any wiggle room. It's something that only exists in your head, as will be clearly pointed out below. I arrived in this discussion after you stated that in was not possible to get acceptable photo results from 100 dpi input, That is not what I said... Here is what I said (and I quote): There is absolutely no chance that I can get a quality image at 100 ppi from my images, 35mm or 2 1/4. Note it says I. and I stated that the HP Photosmart printer used 100 to 150 dpi input on a 300 dpi output system which took advantage of an overprinting method which could supply several drops of ink to the same point on the paper. That's nice, but no one but you were talking about HP printers. Did you just conveniently overlook that the discussion was about Epson printers? I stated that the Photosmart printer produced a reasonable quality result And that's purely opinion, and I personally doubt that it really is reasonable quality at 100ppi. That's a matter of opinion and standards. because of this feature and that I was familiar with this technology because I had discussions with the software engineers who wrote the drivers for this printer, and it was explained to me in some detail how the HP Photosmart system operated. OK, so? You then went on to discuss Epson printers, which I was not talking about, The discussion was in fact about Epson printers (This was not my statement, it is the statement I disagreed with...and I quote): After working with 4-color Epsons for a few years, I've found that the resolution demands of photographs can be quite low, where as few as 100 ppi as a lower limit can produce nice results., ...until YOU mentioned the HP... In reality the discussion was about 100ppi giving quality output, which, HP or Epson, I still claim gives a degraded image. and you stated the reason the colors were not placed upon each other was because the pigmented inks weren't transparent enough. BZZZT. That is not what I said. Once again, you didn't read what was said, and you made things up that I never said. I didn't care what the printing technology or inks, I only mentioned that I BELIEVED Epson printers used pigment inks. This is my exact quote: My understanding is the inks used in these types of inkjet printers can't do that [overprint], simply because the (I believe it's because they are pigmented?) inks don't mix. I know that is true with the Epson inks. Perhaps that particular printer used special inks? I was NOT questioning that the printer you mentioned did or did not do overprinting, and it really doesn't matter if it does or doesn't, that's a tangent to the discussion. Because I had no experience with the printer you mentioned, I wanted to know a bit more about it, and you decided to take this HP tangent... So, I explained that the HP printers I was discussing used dye inks, (other HP consumer printers use dye inks but pigmented black, but their photo type printers use(d) only dye inks including the black) which made your point moot. No point was at all made moot by your bringing up the HP printer. It appears you weren't following the discussion. Apparently, you want to make up what you believe my point was in order to claim it was wrong. My only point was 100ppi doesn't give very good image output unless the prints are very large, or from a very poor negative, I don't care what printer. The discussion wasn't EVER about overprinting (except that you brought up a TANGENT of the HP printer, which I was interested in), and I clearly said that I believed the printer technology wasn't important to this issue. Just because YOU believe the HP printer gave, in YOUR OPINION (which doesn't make it fact) acceptable prints that does not moot that they were degraded images, if they weren't very large or weren't from a very poor negative. And degraded isn't going to be in my opinion, it's a fact that printing a 240ppi image at 100ppi CAN degrade the output. but in the usual fashion, which you always deny you do, you selectively quoted and misrepresented what I said by both taking my information out of context, AND addressing a secondary issue as if it was the point I was trying to make. But, Art, you're accusing me of doing EXACTLY what YOU did! I made one simple statement (about the quality of 100ppi output), you're the one who tangented (brought up the HP printer), and as I
filmscanners: Re: filmscanners: Pixels per inch vs DPI
Is the C70 being sold anywhere around the world now? http://www.epson.com.au/products/home_and_office/C70.html Yes. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote: That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud. I suspected I should have chosen a word other than argument. The number 9 is larger than the number 4 because it is a convention that 9 is 5 integer values larger than 4. Other than that, the digit 9 or the word nine are simply labels to represent an idea. Saying it is because it is does not constitute any sort of meaningful explanation. Claiming that a pixel has anything to do with physics is an odd thing to do. A pixel is a number or a set of numbers that represent a mixture and intensity of light. It's not limited by physics. A dye cloud has a certain dimension and a certain behviour with light. A pixel is not limited in the same way. A pixel could represent an area the size of an atom, or the size of a galaxy; *any* dimension and it may be an 8 bit number or you could pick any number of bits. How small would you like to make the area represented by the pixel and how many bits of RGB would you like to use until you exceed the data contained in a chemical representation of an image? I'm astonished that you could believe the fact you have stated above. But please Austin, let's drop this since it isn't helping anyone with anything to do with filmscanning as far as I can make out? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
RE: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote: That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud. I suspected I should have chosen a word other than argument. The number 9 is larger than the number 4 because it is a convention that 9 is 5 integer values larger than 4. Other than that, the digit 9 or the word nine are simply labels to represent an idea. Saying it is because it is does not constitute any sort of meaningful explanation. Some things just are, and the truth is manifested in and of it self. A basket that has 25 eggs in it has MORE eggs than a basket with 4, right? All semantics aside. Here is (one of) your original question(s)/statement(s), which I have been answering: I don't see why stochastic or random dye clouds inherently provides more information than a pixel. The point of contention appears to be more information. I believe we agree on what more and information mean. Pixels ONLY represent the tonal value of the area which the sensor sees, which does NOT represent the physical characteristics of the dye cloud, unless the dye cloud is perfectly square and happens to line up perfectly in the field of view of that one pixel. In fact a pixel MAY represent many dye clouds, or only a portion of a single dye cloud, but there is NO way you can represent the amount of information in a single dye cloud by a single pixel, when A pixel ONLY contains tonal information. Dye clouds are irregular in shape, and dye clouds do NOT line up 1:1 with pixels. Even if you did characterize each and every dye cloud digitally, you would need more than spot tonal information, You would also have to use many pixels, or characterize the shape, because it's irregular. Characterizing the shape will be very consuming (as in a lot of data) to represent. Given all that, I believe it is obvious why a dye cloud provides inherently more information than a pixel. If you don't see that, I can't explain it any further without sitting down at a white board and drawing it out step by step... Claiming that a pixel has anything to do with physics is an odd thing to do. Now that's an odd thing to do...claim a pixel has nothing to do with physics... I don't know about your scanner, but mine is not Gnostic. A pixel is a number or a set of numbers that represent a mixture and intensity of light. It's not limited by physics. A pixel has an analog to digital origin in our case. This analog to digital conversion has limitations, which ARE limitations of physics. That's just a fact. If you created a drawing with Adobe Illustrator, then your pixels would not have an analog origin. A dye cloud has a certain dimension and a certain behviour with light. A pixel is not limited in the same way. Er, a pixel is FAR more limited, since it is only representing a single characteristic of a regular patterned point source (as in a single element in a regular grid pattern of equal sized elements). A pixel could represent an area the size of an atom, or the size of a galaxy; *any* dimension Except for the fact that we are talking about film scanners, and the are a pixel can represent is limited by physics... and it may be an 8 bit number or you could pick any number of bits. Yes, and it ONLY represents tonality, NO other characteristic at all is represented by a pixel. How small would you like to make the area represented by the pixel and how many bits of RGB would you like to use until you exceed the data contained in a chemical representation of an image? Then you said it's just a matter of increasing the resolution of the grid... Which is where the physical characteristics come in play. There are physical limitations as to how many pixels you can practically use in a scanning system. You can't just make a sensor of infinite density (or infinite size and use optics), since these bring up physical limitations. These are just facts of physics, and why physics is involved. I'm astonished that you could believe the fact you have stated above. Because what I have stated ARE facts. It would take MANY MANY pixels to represent the physical characteristics of a single dye cloud, and one could argue for quite some time what is the correct number of pixels to do this...and NO, because of physical limitations on sensor element sizes (that are NOT the same as faster processors, larger memory etc...those aren't analog sensors, so advances in those areas are not entirely applicable to advances in digital imaging sensors in this case) you can not just increase the resolution of the grid.
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
I agree about the eventually partbut not yet. I am talking about what is now, not what is theoretically possible, and probable. We essentially, are in agreement. Harvey Ferdschneider partner, SKID photography, NYC Rob Geraghty wrote: SKID Photography [EMAIL PROTECTED] wrote: While I agree that the pixels will be 'smoother' because of the inkjet dither pattern, film grain still contains/imparts more information (on a one to one basis) than a pixel, not matter how it is dithered by the printer. Why? So far I've heard this claimed a number of times, but I've still heard nothing which backs it up. I'm prepared to be convinced, but you haven't explained the facts behind the statement you make above. Are we talking about any theoretical pixel, or the average 24 bit pixel? If we're just talking 24bits per pixel, and 2700 or 4000dpi then absolutely the film contains more information. QED. But if the area represented by the pixel is similar to the area of the smallest dye cloud in the film, and the pixel has enough bits to represent colour, I can't see any reason why the film would contain any more useful information than the digital representation, or the why the digital image would be inherently worse. :-7 Everyone has been telling me that we will all inevitably end up using filmless systems. What changed? I know a digital image is only a representation of an analogue event of light, but an image on film is much the same - a representation with limits. Eventually, the digital image will become as good or better than the film image according to market demands. I suspect this discussion is not really relevent to film scanning any more, other than to say that film scanning is a stopgap between film with chemical production of prints and digital imaging. Eventually it will become redundant except for scanning historical material. But we all know that, don't we? :-7 Rob
Re: filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin, Most of what you are saying in this latest missive was brought up before and rejected by Rob. It was at that point that I gave up. But, kudos to you for your tenacity and deep knowledge on this subject. I feel like I've been vindicated, and by someone with far more skill than I. Harvey Ferdschneider partner, SKID Photography, NYC Austin Franklin wrote: Austin wrote: That's the point, it isn't an argument! It's like asking why the number 9 is larger than the number 4. It's just the way it is. It's just a fact of simple physics that a pixel does not contain near the same amount of information as a dye cloud. I suspected I should have chosen a word other than argument. The number 9 is larger than the number 4 because it is a convention that 9 is 5 integer values larger than 4. Other than that, the digit 9 or the word nine are simply labels to represent an idea. Saying it is because it is does not constitute any sort of meaningful explanation. Some things just are, and the truth is manifested in and of it self. A basket that has 25 eggs in it has MORE eggs than a basket with 4, right? All semantics aside. Here is (one of) your original question(s)/statement(s), which I have been answering: I don't see why stochastic or random dye clouds inherently provides more information than a pixel. The point of contention appears to be more information. I believe we agree on what more and information mean. Pixels ONLY represent the tonal value of the area which the sensor sees, which does NOT represent the physical characteristics of the dye cloud, unless the dye cloud is perfectly square and happens to line up perfectly in the field of view of that one pixel. In fact a pixel MAY represent many dye clouds, or only a portion of a single dye cloud, but there is NO way you can represent the amount of information in a single dye cloud by a single pixel, when A pixel ONLY contains tonal information. Dye clouds are irregular in shape, and dye clouds do NOT line up 1:1 with pixels. Even if you did characterize each and every dye cloud digitally, you would need more than spot tonal information, You would also have to use many pixels, or characterize the shape, because it's irregular. Characterizing the shape will be very consuming (as in a lot of data) to represent. Given all that, I believe it is obvious why a dye cloud provides inherently more information than a pixel. If you don't see that, I can't explain it any further without sitting down at a white board and drawing it out step by step... Claiming that a pixel has anything to do with physics is an odd thing to do. Now that's an odd thing to do...claim a pixel has nothing to do with physics... I don't know about your scanner, but mine is not Gnostic. A pixel is a number or a set of numbers that represent a mixture and intensity of light. It's not limited by physics. A pixel has an analog to digital origin in our case. This analog to digital conversion has limitations, which ARE limitations of physics. That's just a fact. If you created a drawing with Adobe Illustrator, then your pixels would not have an analog origin. A dye cloud has a certain dimension and a certain behviour with light. A pixel is not limited in the same way. Er, a pixel is FAR more limited, since it is only representing a single characteristic of a regular patterned point source (as in a single element in a regular grid pattern of equal sized elements). A pixel could represent an area the size of an atom, or the size of a galaxy; *any* dimension Except for the fact that we are talking about film scanners, and the are a pixel can represent is limited by physics... and it may be an 8 bit number or you could pick any number of bits. Yes, and it ONLY represents tonality, NO other characteristic at all is represented by a pixel. How small would you like to make the area represented by the pixel and how many bits of RGB would you like to use until you exceed the data contained in a chemical representation of an image? Then you said it's just a matter of increasing the resolution of the grid... Which is where the physical characteristics come in play. There are physical limitations as to how many pixels you can practically use in a scanning system. You can't just make a sensor of infinite density (or infinite size and use optics), since these bring up physical limitations. These are just facts of physics, and why physics is involved. I'm astonished that you could believe the fact you have stated above. Because what I have stated ARE facts. It would take MANY MANY pixels to represent the physical characteristics of a single dye cloud, and one could argue for quite some time what is the correct number of pixels to do this...and NO, because of physical limitations on sensor element sizes (that are NOT the same as faster
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Rob Geraghty wrote: SKID Photography [EMAIL PROTECTED] wrote: Are you saying that because inkjet printers employ a schoastic dithering pattern to represent pixels that film grain and scan pixels (samples, whatever) are equivalent in regards to the amount of information they impart to an inkjet printer? I think Art was saying that the relationship between pixels in the file and dots on the page isn't clear cut because the dither pattern used by the printer driver is random and therefore undoes some of the regularity of the pixels. The print ends up looking smoother than say a monitor image because the printer shadings aren't constructed as rectilinear sharp edged objects but random spots of colour. Rob While I agree that the pixels will be 'smoother' because of the inkjet dither pattern, film grain still contains/imparts more information (on a one to one basis) than a pixel, not matter how it is dithered by the printer. Harvey Ferdschneider partner, SKID Photography, NYC
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
SKID Photography wrote: Art, I'm not trying to be difficult, but I don't understand what you are trying to say with the below post relative to film grain. Are you saying that because inkjet printers employ a schoastic dithering pattern to represent pixels that film grain and scan pixels (samples, whatever) are equivalent in regards to the amount of information they impart to an inkjet printer? I wouldn't mind if you want to be difficult ;-) But no, I'm, not saying that they are equivalent. But I am saying that inkjet printers get around the defined pixel array and rectangular aspect of pixels (and their defined borders) by using a printing method which randomizes the edges and placement of the dots (as much as by 1/2880th of an inch). Therefore, some of the rigidity of the pixelized nature of digital images is mitigated by the printing process used. One could argue that film isn't continuous tone either, since the size of the dye clouds are random but relatively predetermined by the silver grain size, and they also do not have a full variation of levels of color density. It is the random nature of the three different layers of the grain/dye clouds that creates the analogue result which we find more pleasing, because, as you stated, an array with rigid sized and shaped steps is more obvious to our eye. Unless one works hard at trying to create steplike diagonals, (for instance), which certainly can be visible in a screen image at certain magnifications, it is relatively hard to reproduce these in the inkjet printed image, unless one works at very low resolution. I both ran a color lab and did custom Cibachrome images using fairly good Nikon EL lenses on a Beseler enlarger at home, so I have a fairly good sense of what good prints look like. Using a several year old Epson 850 printer with there photo paper I've been producing 8x10s from scanned 35mm slides, and I'd be hard pressed to pick them out from a reasonable custom type C lab print. Maybe not as good as a Ciba, but fairly close. Other knowledgeable people I show them to agree. The secret for me is to use 1440 dpi, the photo paper setting and the microweave/super printing feature to prevent banding, and error diffusion, and make sure the heads have no clogged nozzles. Sure, with a loupe you'll see some dots (the printer uses down to 4 picolitre dots), but that's smaller than most photo grain appears on a 8x10 print. Art
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Harvey, Just to clarify, my original comments about the randomization of the pixel edges, etc. was in response to your comment below. I was not implying that current pixel resolution could achieve photographic grain randomness or resolution at current. However, I would agree with Rob that should the resolution of digital scans become high enough, the issue would become moot. Grain is just another dot pattern of random size and placement. Seems a bit of fuzzy logic could replicate it should that be desirable, once the resolution is high enough. We humans seem to like analogue qualities in our visual info, sound, etc. Probably because our own cell structure (and that of most living things) is pretty chaotic, and our retinas are certainly not rigid arrays. Film mimics this quality, so we prefer the results. As I said earlier, the placement and relative size of the grain which creates the dye clouds within the film emulsion is predetermined during the manufacturing process. It isn't like they move around after the picture is taken to produce the image, so they could just as easily be detrimentally located as augmenting to the image quality. It's just that they are so small and there are so many that they allow for more precise positioning than do pixels currently. If pixels were small enough, and closely enough spaced, I don't think the issue of their array position would be very important, if there delineation's became fully invisible to the naked eye. Art QUOTED: I think that part of it, is that pixels are aligned in a grid and have a rectilinear shape, whereas the film grain is (for lack of a better description) schoastic in arrangement and irregular in shape, thereby providing more tonal information than pixels. SKID Photography wrote: While I agree that the pixels will be 'smoother' because of the inkjet dither pattern, film grain still contains/imparts more information (on a one to one basis) than a pixel, not matter how it is dithered by the printer. Harvey Ferdschneider partner, SKID Photography, NYC .
Re: filmscanners: Pixels per inch vs DPI
Austin Franklin wrote: The process used a type of overprinting - laying down more than one ink drop per location, If true, that would be interesting. My understanding is the inks used in these types of inkjet printers can't do that, simply because the (I believe it's because they are pigmented?) inks don't mix. I know that is true with the Epson inks. Perhaps that particular printer used special inks? The HP/Kodak Photo RET printing process relies upon overprinting. They do not use pigmented inks, in fact hardly any consumer printers do. Non-photo HP printers use a pigmented black ink. Other than that the only consumer out of box printers using pigmented inks that I'm aware of are the Epson 2000P and the new C80. Others that use pigmented inks, although I wouldn't refer to them as consumer grade, are the Epson 5500, 7500 and 9500, some of the Rolands, and some other larger carriage printers. The other Epsons, including the 3000, and even the 870/890 1270/1290 use dyes, although the later were supposed to be specially designed for longer fade resistance than the average ones. Perhaps at the time, this printer (HP PhotoSmart) looked good, but I doubt it would hold a candle to today's technology. I also believe printer technology is independent of input PPI to the printer driver in the quality of image you will get out of it. That's not to say that different printer technologies don't give different levels of quality output, but that 100 ppi to any technology isn't going to give a very good 8x10... I'll agree that the original HP Photosmart printer looks no better than most drug store snaps. HP sent me a 4x6 and 8x10 sample in 1995, and I still have them. They don't appear to have lost any color (they were not displayed, however), and they look at least as good as typical color machine prints, but with higher saturation, more like a Ilfochrome, and with a nice glossy surface too. The deepest shadow areas show a bit of streaking/banding, which I suspect was due to the inks not drying fast enough. They look pretty similar to Epson Photo or Photo 700 prints, but not as good as 1270/1290 prints. Then again, at the time (1995) a fairly low fading photo quality inkjet printer was a pretty amazing concept. Regardless, the input was 100-150 dpi, and the results were as photographic as a good machine photo print, which I think anyone would call a photograph back then or today. Speaking of inkjets, I was on the Epson website yesterday, and they have lowered the price of the 980 to $99 US! This is an amazing deal. This is a 2880 x 720 printer, with a variable dot going down to a 3 picolitre dot and it is fast. It also has the second largest ink cartridges of all the consumer letter width carriage printers. What I really like about it is that with that size dot, the need for the 6 color printing design is very nearly eliminated, saving a lot of ink by using very small dot instead. This printer, which basically is the upgrade of the 900, is a sturdy printer too, of the older squarer design. The 900 didn't have the chipped cartridge, but I'm not sure if the 980 does or not. Anyway, it is a very good deal for anyone looking for a dye based inkjet that is 4 color, fast and well built, with a letter size carriage. Art
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
I couldn't (and probably didn't) say it better myself ;-) Art Rob Geraghty wrote: SKID Photography [EMAIL PROTECTED] wrote: Are you saying that because inkjet printers employ a schoastic dithering pattern to represent pixels that film grain and scan pixels (samples, whatever) are equivalent in regards to the amount of information they impart to an inkjet printer? I think Art was saying that the relationship between pixels in the file and dots on the page isn't clear cut because the dither pattern used by the printer driver is random and therefore undoes some of the regularity of the pixels. The print ends up looking smoother than say a monitor image because the printer shadings aren't constructed as rectilinear sharp edged objects but random spots of colour. Rob .
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
SKID Photography [EMAIL PROTECTED] wrote: While I agree that the pixels will be 'smoother' because of the inkjet dither pattern, film grain still contains/imparts more information (on a one to one basis) than a pixel, not matter how it is dithered by the printer. Why? So far I've heard this claimed a number of times, but I've still heard nothing which backs it up. I'm prepared to be convinced, but you haven't explained the facts behind the statement you make above. Are we talking about any theoretical pixel, or the average 24 bit pixel? If we're just talking 24bits per pixel, and 2700 or 4000dpi then absolutely the film contains more information. QED. But if the area represented by the pixel is similar to the area of the smallest dye cloud in the film, and the pixel has enough bits to represent colour, I can't see any reason why the film would contain any more useful information than the digital representation, or the why the digital image would be inherently worse. :-7 Everyone has been telling me that we will all inevitably end up using filmless systems. What changed? I know a digital image is only a representation of an analogue event of light, but an image on film is much the same - a representation with limits. Eventually, the digital image will become as good or better than the film image according to market demands. I suspect this discussion is not really relevent to film scanning any more, other than to say that film scanning is a stopgap between film with chemical production of prints and digital imaging. Eventually it will become redundant except for scanning historical material. But we all know that, don't we? :-7 Rob
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: Rob wrote: I don't see why stochastic or random dye clouds inherently provides more information than a pixel. Actually, FAR more. It's their position and size, not their color, that is far more information than pixels are. Pixels (in current implementations) must fall on a grid pattern, and are a fixed size. But the information in a pixel is limited only by the number of bits used to represent the colour. But a dye cloud is more than color. It is ALSO shape and position. Those characteristics (information) are NOT represented by color. Can you explain your claim in some way that shows me how one is better than the other? If you're comparing say a 2700dpi pixel grid with a film emulsion, then I agree. But as far as I can tell, it's just a matter of increasing the resolution of the grid and/or the number of bits in each pixel and you should be able to meet or exceed the amount of information stored in the film. Yes, but increase it to what? You would need to be able to scan the exact edges of every randomly placed dye cloud...it's about three orders of magnitude more information than is currently possible. For practical purposes there has to be a point where the difference becomes irrelevent, or people wouldn't use scanning back cameras or really high res CCD cameras in professional situations. Well, there's yet another problem. You can only make a CCD (or CMOS) pixel just so small, and you are limited also by size of the array. This is a physics limitation. Each and every pixel has to have wires running to and from it. That is not the case with dye clouds ;-) Also, the smaller you make them, the more noise you get. This is the reason the cheapo digital cameras use the small pixel arrays and they are not as good as the larger arrays (physical size, not more pixels) as far as picture quality. Hence, the Canon D30 is FAR better than a same or more sized cheapo digital camera.
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: But a dye cloud is more than color. It is ALSO shape and position. Those characteristics (information) are NOT represented by color. How is a randomly sized and shaped dye cloud a useful characteristic of shape and position? How is it more useful than a precise position in an array? Yes, but increase it to what? You would need to be able to scan the exact edges of every randomly placed dye cloud...it's about three orders of magnitude more information than is currently possible. Now you're talking scanning, which I wasn't. I was talking about representing an image with a pixel array, not the process of getting the image into the array. If you scan film, you're making the process a lot harder than other methods of digitally capturing an image. We've already spent a lot of bandwidth talking about aliasing and other limitations of scanning! Well, there's yet another problem. You can only make a CCD (or CMOS) pixel just so small, and you are limited also by size of the array. This is a physics limitation. Dye clouds are subject to limitations of size as well. This is a spurious argument. Hence, the Canon D30 is FAR better than a same or more sized cheapo digital camera. And the technology used in today's base model computers was top of the line or didn't exist a year or two ago. When I was at university, people were convinced that physics severely limited the size of transistors and the speed at which they operated. The first IBM PC ran at what, 4.77 MHz? And now you can buy a 2GHz PIV? If the market is there, the technology will be developed to meet the demand. Absolutely I agree that Provia 100F and Reala in their own way can store more information in an image than a D30. But look at how quickly the technology has advanced to produce the D30. The rate of improvement in digital imaging is much greater than the rate of improvement in film technology. I don't think anyone is doubting that film is doomed for the majority of consumers are we? Surely it's just a question of time? But meanwhile, I'll continue to try to get the most out of my scanner, and improve my skills at achieving a good result. :) Rob
Re: filmscanners: Pixels per inch vs DPI
Arthur Entlich [EMAIL PROTECTED] wrote: the only consumer out of box printers using pigmented inks that I'm aware of are the Epson 2000P and the new C80. There's another Epson; I think the C70. It's basically the same as the C80 but a little slower. Uses the same carts. Rob
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: But a dye cloud is more than color. It is ALSO shape and position. Those characteristics (information) are NOT represented by color. How is a randomly sized and shaped dye cloud a useful characteristic of shape and position? How is it more useful than a precise position in an array? Because it is. It's the way the world works. It IS additional information, plain and simple. Usefulness is a completely different issue, but it is ALSO useful, to a point. Yes, but increase it to what? You would need to be able to scan the exact edges of every randomly placed dye cloud...it's about three orders of magnitude more information than is currently possible. Now you're talking scanning, which I wasn't. I was talking about representing an image with a pixel array, not the process of getting the image into the array. If you scan film, you're making the process a lot harder than other methods of digitally capturing an image. Absolutely not true. Film scanning is STILL better than any digital camera in existence. We've already spent a lot of bandwidth talking about aliasing and other limitations of scanning! Certainly NOT with me you haven't. How come a drum scanner can scan at 10k/inch if film scanning is so limited? Well, there's yet another problem. You can only make a CCD (or CMOS) pixel just so small, and you are limited also by size of the array. This is a physics limitation. Dye clouds are subject to limitations of size as well. This is a spurious argument. It's important to understanding what is going on here. It's really simple, and why you are fighting it, I can't understand. Hence, the Canon D30 is FAR better than a same or more sized cheapo digital camera. And the technology used in today's base model computers was top of the line or didn't exist a year or two ago. BZZT. Wrong answer. Entirely different issue. We are talking about sensors, which are analog data acquisition devices...and that is apples and oranges compared to computer technology. The limitations are entirely different. I described the limitations of digital camera sensors. These limitations are fact. I don't think anyone is doubting that film is doomed for the majority of consumers are we? Surely it's just a question of time? That may be true, but it has nothing to do with the issues above. General consumers were happy with Polaroid pictures for God's sake! But meanwhile, I'll continue to try to get the most out of my scanner, and improve my skills at achieving a good result. :) To get the most out of your scanner, I would suggest getting good a using good films, exposing them accurately and developing them for low grain. These are really key to getting good images out of scanners.
RE: filmscanners: Pixels per inch vs DPI
Others that use pigmented inks, although I wouldn't refer to them as consumer grade, are the Epson 5500, 7500 and 9500, some of the Rolands, and some other larger carriage printers. The other Epsons, including the 3000, and even the 870/890 1270/1290 use dyes, although the later were supposed to be specially designed for longer fade resistance than the average ones. The ink technology wasn't the issue, the issue was the Epson printers you mention do not place more than one drop of ink on any one spot...no matter what their ink technology is...
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Rob Geraghty wrote: I think that's an important point - we all have different standards. I have a photographic print on my wall at home which everyone I know loves, yet it was made from ordinary 100ASA Kodak print film back in about 1982. It's quite grainy! The point is you would normally view it from halfway across the room, not at reading distance. For me, this is the sort of situation where a print with less than 240 ppi would work. I think it's important to remember that film grain and pixels are not interchangeable terms. One can have a really grainy image, blown way up and still have a full rich tonal range and luminescence, where as the same cannot be said for a digital output that has too few pixels. I think that part of it, is that pixels are aligned in a grid and have a rectilinear shape, whereas the film grain is (for lack of a better description) schoastic in arrangement and irregular in shape, thereby providing more tonal information than pixels. I know that there are those out there that think grain is a dirty word and that the presence of it, limits the possible size or viewing distance of a print. But go to any museum with a good photo collection and you will see that the masters were easily able to get beyond those artificial limitations. That is not to say that the grainy images will be the same as an 8x10 contact print. Separate but equal. Harvey Ferdschneider partner, SKID Photography, NYC
Re: filmscanners: Pixels per inch vs DPI
(still chuckling :) Thanks for the very refreshing posts, Wire! Makes me glad I came back.. Hey, Austin.. Drop the loupe, hop up from your desk, stick an 11 x 17 300dpi print on the wall next to a 200 and a 100 - and then take 2 steps backward.. It is generally agreed that your average photolab print is at best 200 dpi, and yet they are quite sharp even under close, say 10, scrutiny. So for an image that will be viewed at 24 or more, 100 dpi may be not only acceptable, but *extremely* acceptable. I agree 240 dpi and up is nice, but I would strongly encourage folk to *try* lower resolutions and decide for themselves. You may find those images you were scared to crop because they would end up with too few pixels, may just be usable after all.. Umm, maybe it is just that your printer doesn't work well at 100 dpi, Austin..? :-)) mark t (quickly ducking for cover!) Earlier, Wire pontificated: Actually, I'm blind. I was in despair until I found this photography hobby. Now it's all that keeps me going... Seriously, I mean 100 ppi sent to the printer, not a 100 pixel wide image! I have standards. ... OK, the truth is I have very low standards... Oh, never mind. I shouldn't have said anything :) Wire Austin wrote: .. There is absolutely no chance that I can get a quality image at 100 ppi from my images, 35mm or 2 1/4. I really can't imagine every seeing a 100ppi output that was nice... Even 180 is too low, except for the largest of images I print. 240 is about the minimum acceptable resolution I can send to the printer, or image quality degrades quite noticeably. We obviously have different standards is all I can guess. ... This message was sent through MyMail http://www.mymail.com.au This message was sent through MyMail http://www.mymail.com.au
RE: filmscanners: Pixels per inch vs DPI
Seriously, I mean 100 ppi sent to the printer, not a 100 pixel wide image! I have standards. I knew you meant 100ppi sent to the printer...and as I said, I can't imagine how you are getting quality images at 100ppi, unless they are small images like 4x6 or very poor negatives that don't have much detail. If that works for you, then of courst that's great...but it goes against all my experience. OK, the truth is I have very low standards... Ah, well that explains it ;-)
Re: filmscanners: Pixels per inch vs DPI
The original HP Photosmart printer (the big boxy one), which at the time produced some of the best photo-quality images that came out of an inkjet printer, was designed around input of 100-150 ppi, and used 300 ppi output based upon a 6 color (CcMmyK) process. In fact, if memory serves me, it couldn't use input over 150 ppi. The process used a type of overprinting - laying down more than one ink drop per location, which is why HP didn't like to speak about output dpi, because they felt it unfairly sounded too low compared to competitive products, which at that time, were claiming up to 720 dpi. And, because I know Austin will ask, this came from the guy who wrote the printer drivers. Art Wire Moore wrote: Actually, I'm blind. I was in despair until I found this photography hobby. Now it's all that keeps me going... Seriously, I mean 100 ppi sent to the printer, not a 100 pixel wide image! I have standards. ... OK, the truth is I have very low standards... Oh, never mind. I shouldn't have said anything :) Wire on 10/25/01 7:21 PM, Austin Franklin at [EMAIL PROTECTED] wrote: Austin wrote: Why would you want to output at a fixed 300 PPI? Because that's the requirement of the offset printer which many of my recent photos are going to. Aside from that, 300 dpi is as a general rule of thumb the best resolution *most* printers (pc and otherwise) work with. Some [snip] After working with 4-color Epsons for a few years, I've found that the resolution demands of photographs can be quite low, where as few as 100 ppi as a lower limit can produce nice results. You must be talking about very small images, from a very poor negative. There is absolutely no chance that I can get a quality image at 100 ppi from my images, 35mm or 2 1/4. I really can't imagine every seeing a 100ppi output that was nice... Even 180 is too low, except for the largest of images I print. 240 is about the minimum acceptable resolution I can send to the printer, or image quality degrades quite noticeably. We obviously have different standards is all I can guess. There's a book called Real World Scanning Halftones, which explains print dots (spots) in depth. Got it, it's a reasonably good book. .
RE: filmscanners: Pixels per inch vs DPI
Hey, Austin.. Drop the loupe, hop up from your desk, stick an 11 x 17 300dpi print on the wall next to a 200 and a 100 - and then take 2 steps backward.. I have a wall I use for print evaluation. It has a large magnetic white board, and strip magnets on it, used to hold the prints. I put up prints side by side and evaluate them. My largest print size is 17x22 from my 3000. I can see differences from standard viewing distances that have convinced me that 180+ is the minimum resolution that is acceptable to me for the type of work I do, if not 240+ preferred. 100 is vastly degraded. It is generally agreed that your average photo lab print is at best 200 dpi, Where has this been agreed upon? I'm not doubting it, but I never heard that. I also would say that probably doesn't hold true for (especially BW) darkroom prints with decent negatives and decent enlarging lense. Umm, maybe it is just that your printer doesn't work well at 100 dpi, Austin..? :-)) In order for me to print at 100dpi (without decimating the data), I would have to make a VERY VERY large print. For a 2 1/4, I scan at 2540...and that gives me a 24x24 print at 240. I'd be over 50 x 50 if I was to print at 100dpi. Point is, whether 100ppi looks good at all VASTLY depends on print size. Certainly 100ppi will look GREAT if the print is the size of a billboard, but for a 13x19, it looks poor, IMO.
RE: filmscanners: Pixels per inch vs DPI
Austin wrote: My largest print size is 17x22 from my 3000. I can see differences from standard viewing distances that have convinced me that 180+ is the minimum resolution that is acceptable to me for the type of work I do, if not 240+ preferred. 100 is vastly degraded. 'Vastly'? Well, I bow to your excellent eyesight! It sounds like your work includes a lot of BW which does make a difference.. You obviously do have high standards, but don't forget us lesser mortals.. :) (please note - all said in good humour and definitely *not* meant unkindly!) It is generally agreed that your average photo lab print is at best 200 dpi, Where has this been agreed upon? I'm not doubting it, but I never heard that. I also would say that probably doesn't hold true for (especially BW) darkroom prints In my end of the world a 'photo lab' is the downmarket, 1-hour-color-processing type place.. so perhaps we are talking at crossed purposes - if you are talking BW or pro-lab prints, then I agree 200 is too low. As to where it is agreed (or maybe argued!) upon: www.scantips.com 'When we get right down to it, scanning color prints can rarely yield more detail when scanned at more than 300 dpi. And in many cases, that number may be closer to 200 dpi. I am carefully saying color prints, to exclude film and BW prints. In particular, I'm speaking of typical 4X size 35 mm photographic color prints from the photofinisher.' http://www.scanjet.hp.com/ (this quote used to be there, but I can't find it now, I admit) 'The vast majority of scanning projects require resolutions lower than 300 dpi. For example, scanning a photograph at resolutions higher than 150 to 200 dpi only produces a larger file, not more detail.' On the output side, there's some interesting magnified samples here: http://www.imaging-resource.com/TIPS/PRINT1/PRINT1A.HTM Go down to the samples, move right back until the '360' image is clear, and then look at the difference from the 120ppi one. For the *alternate* view, (yes I often argue with myself) and to show that I really don't dispute your opinion, try here (*well* worth a visit): http://www.users.qwest.net/~rnclark/scandetail.htm Here, amongst lots of other interesting stuff, the author shows that 400 ppi is required to get everything off a SHARP print (his emphasis). I would argue that the average joe has probably never seen *that* sort of sharp print :-( , and that a print from a 1-hour lab is about half as good.. Point is, whether 100ppi looks good at all VASTLY depends on print size. AND viewing distance, and image content. :) It's a bit like the debate I have had with people who tell me their 2Mp camera gives superb results when printed to 11x8. Some show me a print, and it can indeed look *darn good*, even up close. But then I say, 'OK, give me the camera and let *me* pick the subject', and the debate is lost - they know images with fine detail will show up the low resolution.. Certainly 100ppi will look GREAT if the print is the size of a billboard, but for a 13x19, it looks poor, IMO. Up-close-and-personal, and on an image with detail, I agree. But what about a slightly soft-focus, close-up, color portrait? I know that's cheating, but my point is that low resolutions like 100 ppi shouldn't be strenuously avoided at all costs. I think members of the list (esp newer ones) should find out for themselves what low-res prints look like, before locking their brains into the 240-and-above zone. Just more of that 'variable mileage' we all get, I guess! :-) mark t
RE: filmscanners: Pixels per inch vs DPI
The process used a type of overprinting - laying down more than one ink drop per location, If true, that would be interesting. My understanding is the inks used in these types of inkjet printers can't do that, simply because the (I believe it's because they are pigmented?) inks don't mix. I know that is true with the Epson inks. Perhaps that particular printer used special inks? Perhaps at the time, this printer (HP PhotoSmart) looked good, but I doubt it would hold a candle to today's technology. I also believe printer technology is independent of input PPI to the printer driver in the quality of image you will get out of it. That's not to say that different printer technologies don't give different levels of quality output, but that 100 ppi to any technology isn't going to give a very good 8x10...
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
SKID Photography [EMAIL PROTECTED] wrote: I think it's important to remember that film grain and pixels are not interchangeable terms. I didn't mean to imply that they were. I was simply trying to make an analogy about expected viewing distance. I think that part of it, is that pixels are aligned in a grid and have a rectilinear shape, whereas the film grain is (for lack of a better description) schoastic in arrangement and irregular in shape, thereby providing more tonal information than pixels. I don't see why stochastic or random dye clouds inherently provides more information than a pixel. A single pixel can represent one of 16 million colours (more or less depending on your bit depth). A single dye cloud can't. The problem is that our pixel sizes aren't down to dye cloud sizes yet (not in the consumer scanners!), and the printers we print with still can't reproduce quite the same subtlety of colour or tone yet. Owners of 1290's may take me to task there. :) In any case until we get affordable digicams with resolution similar to film, most of us are scanning film at resolutions that result in aliasing of some kind, and therefore don't get all the possible information out of the film. I know that there are those out there that think grain is a dirty word and that the presence of it, limits the possible size or viewing distance of a print. Grain is only a dirty word for me because when I scan grainy film I get aliasing. If I could scan at (say) 8000ppi and print a 20x30 image, I might be able to reproduce that photographic enlargement. Actually, for A3 sized prints I've already improved on it because after scanning I was able to remove the dust and scratches from the neg. :) Rob
Re: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: side by side and evaluate them. My largest print size is 17x22 from my 3000. I can see differences from standard viewing distances that have convinced me that 180+ is the minimum resolution that is acceptable to me for the type of work I do, if not 240+ preferred. 100 is vastly degraded. Hi Austin, Do you have another printer? The reason I ask is that the 3000 is very long in the tooth. I had a print from Lyson demonstrating their long life inks, and the dithering was pretty ugly compared to the Photo 700 I had at the time. I'm just wondering how the output from an 1160 or 1290 at 100dpi compares with the 3000, and yes I know you can't print as big. :) Rob
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
I don't see why stochastic or random dye clouds inherently provides more information than a pixel. Actually, FAR more. It's their position and size, not their color, that is far more information than pixels are. Pixels (in current implementations) must fall on a grid pattern, and are a fixed size.
RE: filmscanners: Pixels per inch vs DPI
Hi Austin, Do you have another printer? Yes. Another 3000 ;-) and two 1160s. The reason I ask is that the 3000 is very long in the tooth. Well, it ends up that it's still the absolute best printer for Piezography, much to my delight! I'm just wondering how the output from an 1160 or 1290 at 100dpi compares with the 3000, and yes I know you can't print as big. :) For BW (Piezography) the 3000 is FAR better than the 1160. Even the Cone boys make that claim. For color, I don't really know. What color I printed I thought was pretty bad...but I never really tried to get good photo-like color images out of my inkjet printers yet. Some day I will...
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Art, I'm not trying to be difficult, but I don't understand what you are trying to say with the below post relative to film grain. Are you saying that because inkjet printers employ a schoastic dithering pattern to represent pixels that film grain and scan pixels (samples, whatever) are equivalent in regards to the amount of information they impart to an inkjet printer? Harvey Ferdschneider partner, SKID Photography, NYC Arthur Entlich wrote: Pixels are pretty much only in an array and rectangular on a monitor or a continuous tone printer output. Since inkjet printers use a sub-array of randomized dots to create the illusion of a specific pixel color (usually blended into its surrounding pixel neighbors, as well), there is rarely any true delineation of rectangular pixels in inkjet prints, which use either dithering or an error diffusion pattern to create blends. Art SKID Photography wrote: Rob Geraghty wrote: I think that's an important point - we all have different standards. I have a photographic print on my wall at home which everyone I know loves, yet it was made from ordinary 100ASA Kodak print film back in about 1982. It's quite grainy! The point is you would normally view it from halfway across the room, not at reading distance. For me, this is the sort of situation where a print with less than 240 ppi would work. I think it's important to remember that film grain and pixels are not interchangeable terms. One can have a really grainy image, blown way up and still have a full rich tonal range and luminescence, where as the same cannot be said for a digital output that has too few pixels. I think that part of it, is that pixels are aligned in a grid and have a rectilinear shape, whereas the film grain is (for lack of a better description) schoastic in arrangement and irregular in shape, thereby providing more tonal information than pixels. I know that there are those out there that think grain is a dirty word and that the presence of it, limits the possible size or viewing distance of a print. But go to any museum with a good photo collection and you will see that the masters were easily able to get beyond those artificial limitations. That is not to say that the grainy images will be the same as an 8x10 contact print. Separate but equal. Harvey Ferdschneider partner, SKID Photography, NYC .
Re: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: Well, it ends up that it's still the absolute best printer for Piezography, much to my delight! Ah, but the Piezo printer driver completely replaces the Epson one. For BW (Piezography) the 3000 is FAR better than the 1160. Even the Cone boys make that claim. For color, I don't really know. What color I printed I thought was pretty bad...but I never really tried to get good photo-like color images out of my inkjet printers yet. Some day I will... OK, didn't realise you were using Piezo drivers. Something I have no experience with. I was talking about the imporvements in Epson's drivers from the older models to the current ones. The behaviour of Cone's driver with input resolution may be totally different to the Epson drivers. Rob
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin Franklin [EMAIL PROTECTED] wrote: Rob wrote: I don't see why stochastic or random dye clouds inherently provides more information than a pixel. Actually, FAR more. It's their position and size, not their color, that is far more information than pixels are. Pixels (in current implementations) must fall on a grid pattern, and are a fixed size. But the information in a pixel is limited only by the number of bits used to represent the colour. I don't see why a random pattern of dyes would represent an image better than a grid pattern of pixels with a point size equivalent to the size of the smallest dye cloud. Can you explain your claim in some way that shows me how one is better than the other? If you're comparing say a 2700dpi pixel grid with a film emulsion, then I agree. But as far as I can tell, it's just a matter of increasing the resolution of the grid and/or the number of bits in each pixel and you should be able to meet or exceed the amount of information stored in the film. For practical purposes there has to be a point where the difference becomes irrelevent, or people wouldn't use scanning back cameras or really high res CCD cameras in professional situations. Rob
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
SKID Photography [EMAIL PROTECTED] wrote: Are you saying that because inkjet printers employ a schoastic dithering pattern to represent pixels that film grain and scan pixels (samples, whatever) are equivalent in regards to the amount of information they impart to an inkjet printer? I think Art was saying that the relationship between pixels in the file and dots on the page isn't clear cut because the dither pattern used by the printer driver is random and therefore undoes some of the regularity of the pixels. The print ends up looking smoother than say a monitor image because the printer shadings aren't constructed as rectilinear sharp edged objects but random spots of colour. Rob
Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Chapter 14 of Professional Photoshop - Resolving the Resolution Issue: printed dots per inch consist of grids of spots per dot - of differing picoliter sizes depending on the printer. Apples and oranges? Maris - Original Message - From: Rob Geraghty [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, October 26, 2001 8:17 PM Subject: Re: filmscanners: RE: filmscanners: Pixels per inch vs DPI | SKID Photography [EMAIL PROTECTED] wrote: | Are you saying that because inkjet printers employ a schoastic dithering | pattern to represent pixels that film | grain and scan pixels (samples, whatever) are equivalent in regards to the | amount of information they impart | to an inkjet printer? | | I think Art was saying that the relationship between pixels in the file and | dots on the page isn't clear cut because the dither pattern used by the | printer driver is random and therefore undoes some of the regularity of the | pixels. The print ends up looking smoother than say a monitor image because | the printer shadings aren't constructed as rectilinear sharp edged objects | but random spots of colour. | | Rob | | |
Re: filmscanners: Pixels per inch vs DPI
on 10/23/01 1:36 AM, Julian Robinson at [EMAIL PROTECTED] wrote: And I don't understand the advantage in differentiating between scanner pixels and screen pixels or any other pixel - just makes things more complex? Julian At 15:37 23/10/01, you wrote: I use these terms: Scanner - spi - (scan) samples per inch Monitor - ppi - pixels per inck Printer - dpi - dots (of ink) per inch I think this came from Dan Margulis's Professional Photoshop Maris - Original Message - From: Rob Geraghty [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, October 22, 2001 8:45 PM Subject: filmscanners: Pixels per inch vs DPI I like Maris' terms. Differentiation is important at least because a 1440 dpi printer doesn't print 1440 pixels per inch. It prints dots per inch and a mosaic of dots is required to render an image pixel. With scanners, saying samples per inch tends to suggest samples within the optical resolution of the scanner, although 'over sampling' is a term known in the science of digital signal processing that relates to creating artificial samples using interpolation of actual samples. Raster displays have always been described in terms of pixels, as have raster imaging applications, such as Photoshop. Wire Moore
RE: filmscanners: Pixels per inch vs DPI
With scanners, saying samples per inch tends to suggest samples within the optical resolution of the scanner Not at all. A scanner is an analog data acquisition device, and it IS, in fact, sampling, as in taking samples.
RE: filmscanners: Pixels per inch vs DPI
Austin wrote: Why would you want to output at a fixed 300 PPI? Because that's the requirement of the offset printer which many of my recent photos are going to. Aside from that, 300 dpi is as a general rule of thumb the best resolution *most* printers (pc and otherwise) work with. Some [snip] After working with 4-color Epsons for a few years, I've found that the resolution demands of photographs can be quite low, where as few as 100 ppi as a lower limit can produce nice results. You must be talking about very small images, from a very poor negative. There is absolutely no chance that I can get a quality image at 100 ppi from my images, 35mm or 2 1/4. I really can't imagine every seeing a 100ppi output that was nice... Even 180 is too low, except for the largest of images I print. 240 is about the minimum acceptable resolution I can send to the printer, or image quality degrades quite noticeably. We obviously have different standards is all I can guess. There's a book called Real World Scanning Halftones, which explains print dots (spots) in depth. Got it, it's a reasonably good book.
Re: filmscanners: Pixels per inch vs DPI
Whatever works for each of us I guess. I was trying to point out that printer dots are not relevant to anything that I actually deal with (as in, I don't have to decide on what dpi to set, or allow for it, or even know what it is, to get 'proper' results - apart from as a specification on the day I make my purchase decision (and if you assume that integer relationships are not important with recent printers). I understand that a group of dots make a pixel via dither etc, but my point is that it is not something that you need to or should wrestle with when scanning and printing. Samples per inch at scan time IMHO only confuses the issue - even if I do oversample the result is still a pixel so ppi is still the correct description. From that point on - image processing and printing, it is still a pixel - so for me, call it a pixel at scan time, call it a pixel all the time. The other point I was making has been made by many others, and that is that the only important thing to *track* is the pixel dimensions of the image - trying to track ppi as you work from scanning (2700 ppi) to screen (96/72/100ppi) to printing (300ppi) only makes things complex unnecessarily. So I scan at 2700ppi bec that is my scanner's native resolution, without worrying about any output parameters or sizes. I process in PS without thinking about ppi. WHen I come to print, I resample in PS using the image size box and set an image dimension to suit. Of course I have to check that the resulting ppi is a sensible one, but apart from that don't think it serves any purpose to even think about ppi at other times. I believe most people actually do more or less the same, but lots of complex suggestions pop out when people try to help others on the dreaded dpi/ppi subject which I don't find useful myself. Everybody's MMV! Julian At 11:05 26/10/01, you wrote: I like Maris' terms. Differentiation is important at least because a 1440 dpi printer doesn't print 1440 pixels per inch. It prints dots per inch and a mosaic of dots is required to render an image pixel. With scanners, saying samples per inch tends to suggest samples within the optical resolution of the scanner, although 'over sampling' is a term known in the science of digital signal processing that relates to creating artificial samples using interpolation of actual samples. Raster displays have always been described in terms of pixels, as have raster imaging applications, such as Photoshop. Wire Moore
Re: filmscanners: Pixels per inch vs DPI
Actually, I'm blind. I was in despair until I found this photography hobby. Now it's all that keeps me going... Seriously, I mean 100 ppi sent to the printer, not a 100 pixel wide image! I have standards. ... OK, the truth is I have very low standards... Oh, never mind. I shouldn't have said anything :) Wire on 10/25/01 7:21 PM, Austin Franklin at [EMAIL PROTECTED] wrote: Austin wrote: Why would you want to output at a fixed 300 PPI? Because that's the requirement of the offset printer which many of my recent photos are going to. Aside from that, 300 dpi is as a general rule of thumb the best resolution *most* printers (pc and otherwise) work with. Some [snip] After working with 4-color Epsons for a few years, I've found that the resolution demands of photographs can be quite low, where as few as 100 ppi as a lower limit can produce nice results. You must be talking about very small images, from a very poor negative. There is absolutely no chance that I can get a quality image at 100 ppi from my images, 35mm or 2 1/4. I really can't imagine every seeing a 100ppi output that was nice... Even 180 is too low, except for the largest of images I print. 240 is about the minimum acceptable resolution I can send to the printer, or image quality degrades quite noticeably. We obviously have different standards is all I can guess. There's a book called Real World Scanning Halftones, which explains print dots (spots) in depth. Got it, it's a reasonably good book.
filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote: from my images, 35mm or 2 1/4. I really can't imagine every seeing a 100ppi output that was nice... Even 180 is too low, except for the largest of images I print. 240 is about the minimum acceptable resolution I can send to the printer, or image quality degrades quite noticeably. We obviously have different standards is all I can guess. I think that's an important point - we all have different standards. I have a photographic print on my wall at home which everyone I know loves, yet it was made from ordinary 100ASA Kodak print film back in about 1982. It's quite grainy! The point is you would normally view it from halfway across the room, not at reading distance. For me, this is the sort of situation where a print with less than 240 ppi would work. The biggest print I'm likely to observe at normal reading distance is about A4 (roughly 10x8) and in that situation, the more resolution, the merrier. But when it comes to poster sizes of A3 or larger, I don't think it matters so much - YMMV. :) Rob PS It's not *possible* for me to get 240ppi at A3 unless I get a 400dpi scanner. Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
filmscanners: RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote: Why would you want to output at a fixed 300 PPI? Because that's the requirement of the offset printer which many of my recent photos are going to. Aside from that, 300 dpi is as a general rule of thumb the best resolution *most* printers (pc and otherwise) work with. Some are more, some are less, and the manufacturers muddy the water by talking about the size of individual ink dots not the size at which a pixel is reproduced as a dot on the print. If you are outputting to an inkjet printer, you are best to just choose your image output size and let the PPI output to the printer fall where it may. So what do you set the dpi to in the file? If you create a TIFF file, there will be a figure for the dpi embedded in it. I use 300dpi. When I actually print from PSP the real dpi is hardly ever precisely 300dpi - it depends on the page layout and how the picture is cropped. So yes, I'm effectively doing what you suggest above when prniting on my own printer. But I have to set the file's dpi to something, and it makes more sense to set it to 300dpi than 2700dpi or 100dpi for a full frame 2700spi ( :) scan. If you do any resizing of the PPI to make some fixed number, then you are resampling, which degrades the image. I was talking about the setting in the file. You can set the output dpi of Vuescan (or Nikonscan I think) to anything you want. It makes no difference to the number of pixels. Setting it to 300 dpi means that you'll get a meaningfully sized print (roughly a page) out of a 2700 spi scan on most printers. Leave it at 2700dpi and you'll have a print the size of the neg frame. Set it to 100dpi and the size will be silly for printing. Epsons seem to work quite well at 240dpi because of the integer relationship with the 1440dpi native dot size. That?s pretty much been proven to by a myth. It is true, to some degree, for lineart, but not at all for halftoned images. In my own personal experience it's true that prints having an integer relationship between the output dpi and 1440 on my Epson 1160 will be sharper and have less visible dithering than at other scales. It was also true on my previous Photo 700. I expect that newer printers, particularly those with more than 4 colours, will give better results. I don't know for sure about other printers - for instance the 12x0 series probably have fine enough patterns from 6 colours at 1440 or 2880 dpi that variations in the source dpi make much less difference. I don't know because I don't have one. What I *do* know is that Epson had on their own web site an equation for calculating the ideal source resolution which was based on an integer relationship with the printer's native resolution. Epson themselves said it was the best thing to do. The story may have changed since they wrote that FAQ. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
Re: filmscanners: Pixels per inch vs DPI
Everyone has their own points of confusion and moments of comparative clarity, but this is one discussion about which I have never understood the confusion. I use pixels for everything. Everything that is relevant to me, I mean. The pixels I get out of the scanner becomes the same number of pixels when I work in PS, and is the same number of pixels on screen, and (unless I resample) will be the same number of pixels when I print it. The pixels per inch is only of interest at those moments when I want to transfer from my digital image to a physical sized image or vice versa, and its calculation is straightforward. It seems that thinking of the pixels more than the ppi is much more efficient. I have seen people totally tied in knots trying to fathom how to print their 36x24mm 2700ppi image onto 7x5 paper at 300ppi, but thinking of it as 3800x2500 pixels means the whole thing is straightforward. The tagging of images with ppi figures in PS and other software is an unnecessary confusion - I think it should never be mentioned unless the context at that time is one of transfer to a specific physical sized medium. Even then the ppi should only be mentioned with a kind of flashing red-arrow link to the image size that is implied by that ppi. The fact that the printer happens to separate colors and dither and re-present the image as a greater number of 4 or 6-colour dots is of no significance to me so I ignore it. I suppose it would be different if I needed to understand the printing process, but even then the concept of printer dots does not seem confusing because it is such a different thing from the pixels that the image is stored as. 1440 dpi is an internal printer spec that has no relevance to me other than to define - once- the likely resolution performance of the printer. It is not something I have to work with or calculate with, so I ignore it. And I don't understand the advantage in differentiating between scanner pixels and screen pixels or any other pixel - just makes things more complex? Julian At 15:37 23/10/01, you wrote: I use these terms: Scanner - spi - (scan) samples per inch Monitor - ppi - pixels per inck Printer - dpi - dots (of ink) per inch I think this came from Dan Margulis's Professional Photoshop Maris - Original Message - From: Rob Geraghty [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, October 22, 2001 8:45 PM Subject: filmscanners: Pixels per inch vs DPI
RE: filmscanners: Pixels per inch vs DPI
The reason you're confused is that the term dpi is being used for several things. Certainly a prolific problem. I prefer to say SPI as it relates to the scanner, PPI is what you output TO the printer driver, and DPI is what the printer prints. I've been find of flamed for saying screen resolution is 72dpi but it's a worthwhile rule of thumb. Yes it is, and posting someones opinion isnt a flame at all, not even kind of... 1. Scan at the maximum resolution of your film scanner (eg. 2710 ppi) Optical resolution...agreed. Some scanners list interpolated resolutions as their maximum resolution... 2. If you want to print the picture, the maximum size you can print is limited to the number of pixels expressed at 300 ppi. I always set the output resolution of Vuescan to 300dpi. I have no idea what you mean by that...would you please elaborate?
filmscanners: Pixels per inch vs DPI
Ken wrote: see it relates mostly to size. I'm still not entirely sure why high res scans look better on a screen only capable of displaying 72dpi. I tried a slide at 2720 and then 680 dpi, sized the two scans the same, and the 2720 looked far better, especially under high zooms. The reason you're confused is that the term dpi is being used for several things. Scanner manufacturers talk about their scanners being (say) 2700 dpi. What they mean is that it scans 2700 *pixels per inch*. When you display those pixels at 1:1 on a computer screen which has (say) 72 pixels per inch, you'll only see a small part of the picture. But if you print the picture onto paper using a printer that prints 300 *dots* per inch, your 2700 pixel per inch scan of a 35mm frame will end up around 10x8. AFAICS that's why the scanner manufacturers picked 2700 ppi for their film scanners - it roughly translates to a full A4 page print at 300dpi. Even the printer manufacturers confuse the issue because Epson for instance say their current printers print at 2880x720 dots per inch, but the relationship between pixels on the screen and colour on the page is more like 300 dots per inch! The printer can't print one dot of the colour you want because the inks are only CMYK or CcMmYK, so it needs to use a pattern of dots to make the colour in the file or on the screen. I've been find of flamed for saying screen resolution is 72dpi but it's a worthwhile rule of thumb. Pick 100dpi if you prefer; it's certainly easier to calculate with. If you want a 2 x 2 image on the screen at 100dpi you need 200x200 pixels. The terminology is confusing, and the manufacturers aren't helping. All I've been trying to point out is the relationship between the various resolutions of different media and devices. The rule of thumb I've seen most commonly expressed can be summarised as; 1. Scan at the maximum resolution of your film scanner (eg. 2710 ppi) 2. If you want to print the picture, the maximum size you can print is limited to the number of pixels expressed at 300 ppi. I always set the output resolution of Vuescan to 300dpi. 3. If you want a screen image, you need to resize the scan (or portion of the scan) so that it's about 100 ppi. So a 3000x2000 pixel film scan would have to be reduced by 10x to make a 300x200 pixel image suitable for a small web jpeg. I've used pixels per inch and dots per inch interchangeably and I'll probably be flamed for it. They aren't interchangeable in that you can set a 100x100 *pixel* image to be any *dpi* you want. That will just determine the size of the image when printed. I probably haven't been clear enough in how I've written this, but hopefully you can see how the relationship between pixels and size changes from device to device and medium to medium. FWIW also, Epson photo printers print quite well at 240 ppi or even less, but you'll get a good image at 300ppi on most printers. It's especially important if you want to use a commercial printing company - they will insist on 300dpi images. Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
filmscanners: RE: filmscanners: Pixels per inch vs DPI
Austin wrote: Certainly a prolific problem. I prefer to say SPI as it relates to the scanner, PPI is what you output TO the printer driver, and DPI is what the printer prints. *I* know you mean samples per inch, pixels per inch and dots per inch, but a newbie will find all the terminology confusing - especially when their scanner and printer manufacturers use dpi exclusively in their interfaces. Yes it is, and posting someone?s ?opinion? isn?t a ?flame? at all, not even ?kind of?... *shrug* Of course I don't have a problem with anyone expressing their opinion. Theirs is just as valid (or maybe moreso) than mine. 1. Scan at the maximum resolution of your film scanner (eg. 2710 ppi) Optical resolution...agreed. Some scanners list interpolated resolutions as their maximum resolution... OK, I didn't mention that caveat since most *film* scanners seem to work with optical resolution. My Nikon interface won't let me set an interpolated resolution. Flatbeds are famous for claiming to be 9600dpi when their optical resolution might only be about 300dpi. 2. If you want to print the picture, the maximum size you can print is limited to the number of pixels expressed at 300 ppi. I always set the output resolution of Vuescan to 300dpi. I have no idea what you mean by that...would you please elaborate? OK. I don't have any files to work with here so I'll work with some theoretical numbers. Suppose you scan a 35mm frame at 2700dpi (spi if you prefer :) and get a file containing 3000x2000 pixels. If you want to print the file at 300dpi (or 300 pixels per inch) the maximum print size will be 10 x 6.7. I've just divided the number of pixels by the required number of pixels per inch. In practice the proportions of a 35mm frame should give you about 10x8. This is just a general rule of thumb; translate the pixels to an equivalent 300 pixels per inch and that is the best print size you'll get from the digital image. Caveats: 1. If you want to resample the original scan, you can print at any size you like, but there will be artifacts from the resampling process. 2. As I mentioned earlier, some printers give quite good results at lower dpi. Epsons seem to work quite well at 240dpi because of the integer relationship with the 1440dpi native dot size. Does that make more sense? Rob Rob Geraghty [EMAIL PROTECTED] http://wordweb.com
RE: filmscanners: RE: filmscanners: Pixels per inch vs DPI
2. If you want to print the picture, the maximum size you can print is limited to the number of pixels expressed at 300 ppi. I always set the output resolution of Vuescan to 300dpi. I have no idea what you mean by that...would you please elaborate? OK. I don't have any files to work with here so I'll work with some theoretical numbers. Suppose you scan a 35mm frame at 2700dpi (spi if you prefer :) and get a file containing 3000x2000 pixels. If you want to print the file at 300dpi (or 300 pixels per inch) Why would you want to output at a fixed 300 PPI? If you are outputting to an inkjet printer, you are best to just choose your image output size and let the PPI output to the printer fall where it may. If you do any resizing of the PPI to make some fixed number, then you are resampling, which degrades the image. If you just let the PPI fall where it may (providing you are above 180+, if even 240), then you only get one processing of the image, namely the halftone algorithm in the printer driver (converting PPI to DPI ;-)...and therefore less image degradation. Am I misunderstanding you perhaps? 2. As I mentioned earlier, some printers give quite good results at lower dpi. Epsons seem to work quite well at 240dpi because of the integer relationship with the 1440dpi native dot size. Thats pretty much been proven to by a myth. It is true, to some degree, for lineart, but not at all for halftoned images.
Re: filmscanners: Pixels per inch vs DPI
I use these terms: Scanner - spi - (scan) samples per inch Monitor - ppi - pixels per inck Printer - dpi - dots (of ink) per inch I think this came from Dan Margulis's Professional Photoshop Maris - Original Message - From: Rob Geraghty [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Monday, October 22, 2001 8:45 PM Subject: filmscanners: Pixels per inch vs DPI
