[filmscanners] A number of SS4000 available
I just though I'd mention that a number of used and new Polaroid SS4000 scanners have shown up on ebay. One sold (used) for $450 US. There is also an Microtek Artixscan 4000T for sale over the next few hours. Some have SCSI cards and software. For people seeking these units, you might be able to get a good deal. Also Primefilm 1800U units are selling new for $145-155 US, plus shipping, which is a good deal fro a entry level scanner. Art Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: opinions? Reviews? of Primefilm 1800 ?
Bits equals available grey levels per pixel - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, June 07, 2002 4:22 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Just out of curiousity and in simple layman's terms, what do the number of bits that the converter has have to do with if not the density range? How does it impact on what is captured? Austin, I am asking a serious question here out of my lack of knowledge and sure would appreciate a good discussion in layman's terms so that I can understand what is being said without having to hire an engineer to interpret. It has always been my understanding, rightly or wrongly, that the higher the number of bits the more detailed or refined the informational date captured from the original that is transmitted as data in the digital file with respect to highlight and/or shadow detail with the density range figure represetning the range of contrast that can be captured. In other words, dynamic range representing the contrast range of the capture's capabilities, while the bit depth represented the quality of the data captured within that range particularly the extremes. If this is wrong, please explain where and how it is and provide me with a more accurrate description (but once again, I urge you to try and do it in non-engineering terms if possible). -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Austin Franklin Sent: Friday, June 07, 2002 7:13 AM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? However, it is rated with 3.2 dynamic range, which is a bit low for a 14 bit/channel. Even though they may call it dynamic range, it is DENSITY range. Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Color spaces for different purposes
What color spaces is best to choose for the following purposes: - printed material, for example a magazine or a photographic book - stock photography (image bank) - inkjet I want to scan my images in the most appropriate color space for the purpose but don't want to use some exotic ones. I'd prefer to stick to widely used color spaces (but which ones?) I'm thinking of a small private image bank with my photographs so that I can sell a licence to use my images in different publications easily. Apart from the color space, I'd also like to know whether I should perform sharpening, although it should be the last stage in image processing and whether grain suppression is advisable (I can hear people moaning about lack of sharpness and big grain in images from 4000dpi scanners - they don't realize they are looking at very big pictures on their monitors). Regards Tomasz Zakrzewski Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Hi Laurie, In so far as my use of the two terms in the mistatement, dynamic range and density range tend to be used in the literature and manufacturer's specs synonymously as denoting the same thing (ie. the contrast range), Yes, I know...(heavy sigh). Marketing people tend not to really understand the difference, and neither do most lay people...or even quite a few technical people. They have also been used interchangeably in photography for many many years...unfortunately... Having said that,let me see if I got it by putting it into my own words. Density range refers to the contrast range from white point to black point covered by the scanner and is measured in terms of 3.0 to 4.2 Dmax or D Coorect! Whereas bit depth refers the degree of quality information or detail that can be obtained within the given density range Bit depth is actually nothing more than the limiting factor FOR the detail...but does not assure you that you will get the detail. Thus, in your terms since most of the literature does not use any term to describe what is being measured except to refer to it as bit depth or x number of bits, bit depth measures the dynamic range that a device can capture within its given density range, as meeasured by the Dmax specification. Again, bit depth is the limiting factor OF dynamic range, but does not assure you that the dynamic range of the scanner is equal to the bit depth...as in the 24 bit, w/ 12 bits of noise, example. Is my understanding close enough for government work or do I need to go back to the contemplation place and rethink it? It's fine, if you understand the caveat WRT bit depth... Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Color spaces for different purposes
Tomek writes ... What color spaces is best to choose for the following purposes: - printed material, for example a magazine or a photographic book - stock photography (image bank) - inkjet I want to scan my images in the most appropriate color space for the purpose but don't want to use some exotic ones. I'd prefer to stick to widely used color spaces (but which ones?) ... I'd submit AdobeRGB as probably the most respected and universally appropriate color space ... especially for distribution. Do note however, its gamut is too large for presentation at a wwwsite. For that, you'll need to convert your www presentations to sRGB. cheerios ... shAf :o) Avalon Peninsula, Newfoundland www.micro-investigations.com Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
On Sat, Jun 08, 2002 at 09:43:00AM +0100, dickbo wrote: Bits equals available grey levels per pixel - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, June 07, 2002 4:22 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Just out of curiousity and in simple layman's terms, what do the number of bits that the converter has have to do with if not the density range? How does it impact on what is captured? Austin, I am asking a serious question here out of my lack of knowledge and sure would appreciate a good discussion in layman's terms so that I can understand what is being said without having to hire an engineer to interpret. It has always been my understanding, rightly or wrongly, that the higher the number of bits the more detailed or refined the informational date captured from the original that is transmitted as data in the digital file with respect to highlight and/or shadow detail with the density range figure representing the range of contrast that can be captured. In other words, dynamic range representing the contrast range of the capture's capabilities, while the bit depth represented the quality of the data captured within that range particularly the extremes. If this is wrong, please explain where and how it is and provide me with a more accurrate description (but once again, I urge you to try and do it in non-engineering terms if possible). The number of scanner bits is a necessary but not sufficient requirement for seeing densities at a scanner's theoretical dmax (i.e. log 2^bit-depth). Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. More importantly though the number of bits determine with what resolution the scanner can see the density levels that it is capable of scanning. Reread that last sentence again! Lets take a sample scanner which can only record film density up to a 2.4 dmax. This should be within the realms of even the cheapest modern film scanner hardware. This density limit is imposed by (let's say) the cheap design of the scanner and the manufacturer's requirements to be cost effective. Now lets take this scanner and give it an 8-bit CCD to start with. In a minute we'll give it a 14-bit CCD and see the difference. The number of bits represents the POTENTIAL density range that the scanner is capable of. Scanner CCDs are linear devices - it is important you understand this concept because it determines how well scanners can potentially see into the shadows. With a linear device each doubling or halving of a scanned linear data value represents a doubling or halving of light, or 1 stop, or 0.3 density units. Let us take our 8-bit scanner then - 8-bits gives us a total of 256 values that the scanner can use to scan the image. Let us look at the numbers to see how these data values can be spread out across a density range. I'm going to assume that the operator has placed the scanner's white point (value 255) exactly at the lightest portion of the film/paper. 128-255: 1 stop (0.3 density units) 64-127: 1 stop (0.3 density units) 32-63: 1 stop (0.3 density units) 16-31: 1 stop (0.3 density units) 8-15: 1 stop (0.3 density units) 4-7: 1 stop (0.3 density units) 2-3: 1 stop (0.3 density units) 0-1: 1 stop (0.3 density units) Note that I cannot go any further than this because I need at least two distinct values to represent a change in density. The 8-bit scanner then can scan up to 8 potential stops. It is impossible to see anything denser because it would need more bits. Even now you have so few bits at the shadow end that you would almost certainly have posturization. Let us move now to the same scanner with 14-bits to play with. How do those 8-stops map to the scanner data values? Well 14-bits gives us 16,384 values: 8192-16383: 1 stop (0.3 density units) 4096-8191: 1 stop (0.3 density units) 2048-4095: 1 stop (0.3 density units) 1024-2047: 1 stop (0.3 density units) 512-1023: 1 stop (0.3 density units) 256-511: 1 stop (0.3 density units) 128-255: 1 stop (0.3 density units) 64-127: 1 stop (0.3 density units) Heck we've reached 8-stops here and there's loads of bits to spare! Better still that last stop which, on the 8-bit scanner, could only be represented by either a 0 or 1 can now be represented by 64 distinct values. Undoubtedly you could get better tonal resolution in that last stop of shadow area with 14-bits. What about the values from 0 to 63 I hear you ask? Well as agreed at the start our scanner is only capable of recording up to 2.4 dmax from the film. This is a hardware limitation. What if they came along and created a better
[filmscanners] Re: Color spaces for different purposes
On Sat, Jun 08, 2002 at 11:41:40AM +0200, Tomek Zakrzewski wrote: What color spaces is best to choose for the following purposes: - printed material, for example a magazine or a photographic book - stock photography (image bank) - inkjet I want to scan my images in the most appropriate color space for the purpose but don't want to use some exotic ones. I'd prefer to stick to widely used color spaces (but which ones?) I'm thinking of a small private image bank with my photographs so that I can sell a licence to use my images in different publications easily. Apart from the color space, I'd also like to know whether I should perform sharpening, although it should be the last stage in image processing and whether grain suppression is advisable (I can hear people moaning about lack of sharpness and big grain in images from 4000dpi scanners - they don't realize they are looking at very big pictures on their monitors). Personally I do some sharpening for an archival image that may end up going to different outputs. This is only a minor sharpening to restore the sharpness of the original which is almost always softened by the scanning process. Most images will benefit from further sharpening when targeting for a specific output but this should not really be done for an archival copy. As for colourspace - Adobe RGB is a good bet as it has a reasonable gamut. It's quite important to embed the colourspace profile in the image so the image can easily be converted to other spaces if needed. If you think that others may not be able to handle colourspace information it might be wiser to choose one with a more narrow gamut such as sRGB. -- Tony Terlecki [EMAIL PROTECTED] Running Debian/GNU 2.2 Linux Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
On Sat, 8 Jun 2002 16:17:30 +0100, you wrote: Personally I do some sharpening for an archival image that may end up going to different outputs. This is only a minor sharpening to restore the sharpness of the original which is almost always softened by the scanning process. Most images will benefit from further sharpening when targeting for a specific output but this should not really be done for an archival copy. Speaking of sharpening - I think I understand this in a sort of sloppy intuitive way, but could someone offer a technical explanation of why sharpening has so much more visible effect on jpegs as opposed to TIFFs? Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
Probably the artifacts created in the compression process. It would probably be better to convert to JPG first and then sharpen. Maris - Original Message - From: Ken Durling [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:05 AM Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 16:17:30 +0100, you wrote: Personally I do some sharpening for an archival image that may end up going to different outputs. This is only a minor sharpening to restore the sharpness of the original which is almost always softened by the scanning process. Most images will benefit from further sharpening when targeting for a specific output but this should not really be done for an archival copy. Speaking of sharpening - I think I understand this in a sort of sloppy intuitive way, but could someone offer a technical explanation of why sharpening has so much more visible effect on jpegs as opposed to TIFFs? Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Color spaces for different purposes
It would probably be better to convert to JPG first and then sharpen. Theoretically maybe; but out of curiosity, how does one do this in actuality when one would have to first decompress the JPG file before one could carry out the sharpening operations. Afterwhich, one would then recompress the file again in its altered state which would be what typically causes the artifacts and deterioration in JPG files to begin with? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 11:33 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes Probably the artifacts created in the compression process. It would probably be better to convert to JPG first and then sharpen. Maris - Original Message - From: Ken Durling [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:05 AM Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 16:17:30 +0100, you wrote: Personally I do some sharpening for an archival image that may end up going to different outputs. This is only a minor sharpening to restore the sharpness of the original which is almost always softened by the scanning process. Most images will benefit from further sharpening when targeting for a specific output but this should not really be done for an archival copy. Speaking of sharpening - I think I understand this in a sort of sloppy intuitive way, but could someone offer a technical explanation of why sharpening has so much more visible effect on jpegs as opposed to TIFFs? Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
On Sat, 8 Jun 2002 11:56:29 -0500, you wrote: Theoretically maybe; but out of curiosity, how does one do this in actuality when one would have to first decompress the JPG file before one could carry out the sharpening operations. Afterwhich, one would then recompress the file again in its altered state which would be what typically causes the artifacts and deterioration in JPG files to begin with? Yes, I realized after I typed that what I actually do is resize the TIFF, edit, * sharpen * and THEN go to JPEG. It's in this resized TIFF that I see the increased sharpening or USM effects, over the raw intitial file. Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Color spaces for different purposes
One pre-press expert in my area recommends ColorMatchRGB instead of Adobe98 for pre-press work. Is this a Mac vs. PC thing? Primarily, yes it is both a Mac thing and a preferrential prejudice. From what I understand, the two are very similar in terms of the gammut that they cover. Maris's comment that Some publishers will do the sharpening themselves is more significant that it appears in his remarks. Most publishers not only prefer to do the sharpening themselves but actually do sharpen it themselves even if they receive an already sharpened file so as to bring it into conformity with their printer's needs. Moreover, most publishers prefer to work directly from the digital file rather than from an inkjet produced off that file; hence, they request or require the digital file and not the inkjet print. Thus, you would not know what sharpening would be required for the publisher's intended use; but they would. Given this, you would not want to sharpen the digital file that is supplied to them but give them an unsharpened final version. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Preston Earle Sent: Saturday, June 08, 2002 9:57 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes Tomek Zakrzewski [EMAIL PROTECTED] asked: What color spaces is best to choose for the following purposes: - printed material, for example a magazine or a photographic book - stock photography (image bank) - inkjet and Maris V. Lidaka Sr. [EMAIL PROTECTED] suggested: I also would suggest Adobe RGB. I would not sharpen the images yet - sharpen when you are ready to print on inkjet or to send to the publisher, as your sharpening amount will probably be different. Some publishers will do the sharpening themselves AFAIK. --- Maris has excellent advice. For a fuller story, try a Googlesearch for: (color space RGB colormatch sRGB Adobe) and you will get lot's of informative links. One pre-press expert in my area recommends ColorMatchRGB instead of Adobe98 for pre-press work. Is this a Mac vs. PC thing? Preston Earle [EMAIL PROTECTED] Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
On Sat, 8 Jun 2002 11:33:05 -0500, you wrote: Probably the artifacts created in the compression process. It would probably be better to convert to JPG first and then sharpen. But when printing it's best to go direct from the TIFF isn't it? This is where I run into it. When producing for the web, yes, I go to jpeg and then sharpen. Actually, I often resize the TIFF to the pixel size I want, do the rest of my editing and then sharpen just before converting to JPEG. I get good results this way.Come to think of it, I see a lot more sharpening effect when the TIFF has been resized than before - let alone the JPEG. I also haven't experimented with the for print output setting in Vuescan - any idea what this does differently? Ken Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Hi Tony, Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. Not true. You can represent ANY density by any number of bits. I can represent an entire density range with two bits: 00 - at or below dMin 10 or 01 - between dMin and dMax 10 - at or below dMax BTW, that should be at or ABOVE dMax...sorry. This is a completely valid encoding of density range. I have to run now, so I'll comment on the rest of your post later. Regards, Austin And...to add further to this, as I have a few moments... Density values are absolute values, just like one foot is an absolute value. They have meaning in and of them selves. Someone decided what the exact length of one foot is (within a tolerance of course), as well as density values. They mean the same thing everywhere...a density value of 1.6 means exactly that in La Jolla CA, as well as in Pascagoula, MS. Same with one foot. But, the tonal values out of a scanner are not the same everywhere, nor are they the same even between scans! The value 136 in La Jolla, CA...does not have the same tonality as the value 136 in Pascagoula, MS. Scanners are not calibrated TO anything, except themselves. That is why the data values you get from the scanner are not the same density values. There is no direct correlation between them, unless you were to calibrate your scanner in the same way densitometers are calibrated (even that is insufficient, as the sensors used in film scanners have different characteristics than the sensors used in densitometers). Now, WHY would anyone in the first place say that number of bits has anything to do with density range...because they made some erroneous assumptions. Density range is stated in a ratio of to 1 (:1), and a density of 3.6 is 10**3.6:1 or 3981:1 (and someone, at some time, decided what the density value of 1 physically is), which the number 3981 requires 12 bits to represent in the binary system, if you are going to represent every integer value from 1 to 3981...BUT...that's the rub...a value of 3981 from the scanner is NOT the same as a density value of 3.6 (3981:1), for the reasons explained above. And, no, they are not close enough for government work ;-) Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Hi Austin, Yes I am fully cognizant of the fact that we are talking about optimum conditions and limits under usually ideal conditions when we talk about capabilities or capacities and that we are not talking about certainties in practice under practical concrete empirical conditions. Thanks. I think I am clear on this now; at least, I am until some engineer comes around throwing techical talk at me about the subtlties involved which will only muddy up the water for me. :-) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Austin Franklin Sent: Saturday, June 08, 2002 6:42 AM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ? Hi Laurie, In so far as my use of the two terms in the mistatement, dynamic range and density range tend to be used in the literature and manufacturer's specs synonymously as denoting the same thing (ie. the contrast range), Yes, I know...(heavy sigh). Marketing people tend not to really understand the difference, and neither do most lay people...or even quite a few technical people. They have also been used interchangeably in photography for many many years...unfortunately... Having said that,let me see if I got it by putting it into my own words. Density range refers to the contrast range from white point to black point covered by the scanner and is measured in terms of 3.0 to 4.2 Dmax or D Coorect! Whereas bit depth refers the degree of quality information or detail that can be obtained within the given density range Bit depth is actually nothing more than the limiting factor FOR the detail...but does not assure you that you will get the detail. Thus, in your terms since most of the literature does not use any term to describe what is being measured except to refer to it as bit depth or x number of bits, bit depth measures the dynamic range that a device can capture within its given density range, as meeasured by the Dmax specification. Again, bit depth is the limiting factor OF dynamic range, but does not assure you that the dynamic range of the scanner is equal to the bit depth...as in the 24 bit, w/ 12 bits of noise, example. Is my understanding close enough for government work or do I need to go back to the contemplation place and rethink it? It's fine, if you understand the caveat WRT bit depth... Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: opinions? Reviews? of Primefilm 1800 ?
Bits equals available grey levels per pixel That is nice; is this also true when one works in color as opposed to grayscale or black and white? Would I be wrong to generalize this and say bits equal potentially available tonal levels per pixel in which the tone can be any hue or color? However, the question in issue, I believe, was not the meaning of bits but if bit depth was intended to be a measure of dynamic range or of density range, of the contrast range from white point limit to black point limit or of the ability to discriminate between shades or tones within that contrast range, or more generally between the quantity of informational data regarding highlights and shadows and the quality of that information in terms of determining details precisely within that contrast range. While I am inclined to agree that from your definition or mine of bits the reference of bit depth should be apparant, it does not appear to be in regards to its actual usage, which I believe is what gave rise to the discussion. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of dickbo Sent: Saturday, June 08, 2002 3:43 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: opinions? Reviews? of Primefilm 1800 ? Bits equals available grey levels per pixel - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, June 07, 2002 4:22 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Just out of curiousity and in simple layman's terms, what do the number of bits that the converter has have to do with if not the density range? How does it impact on what is captured? Austin, I am asking a serious question here out of my lack of knowledge and sure would appreciate a good discussion in layman's terms so that I can understand what is being said without having to hire an engineer to interpret. It has always been my understanding, rightly or wrongly, that the higher the number of bits the more detailed or refined the informational date captured from the original that is transmitted as data in the digital file with respect to highlight and/or shadow detail with the density range figure represetning the range of contrast that can be captured. In other words, dynamic range representing the contrast range of the capture's capabilities, while the bit depth represented the quality of the data captured within that range particularly the extremes. If this is wrong, please explain where and how it is and provide me with a more accurrate description (but once again, I urge you to try and do it in non-engineering terms if possible). -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Austin Franklin Sent: Friday, June 07, 2002 7:13 AM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? However, it is rated with 3.2 dynamic range, which is a bit low for a 14 bit/channel. Even though they may call it dynamic range, it is DENSITY range. Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range
Now lets take this scanner and give it an 8-bit CCD to start with. In a minute we'll give it a 14-bit CCD and see the difference. Wouldn't that be an 8- (or 14) bit A/D converter, rather than CCD? In other words, are not CCDs analog devices providing voltages that are converted to digital representation? Denis Hill, QPP --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.362 / Virus Database: 199 - Release Date: 5/7/2002 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Tony, Thank you for your lengthy and detailed response. I am posting this just to let you know that I have not had time to give it the reading and thought it desearves yet; but I will get back to you when I have had an opportunity to read and digest it. I did notice in the headers that under the second original message header it says that the message was from me to [EMAIL PROTECTED] when in actuality the original message of mine was to Austin not Dickbo. In fact, I did not see Dickbo's post until well after I posted the quoted message of mine. Not that this means anything in terms of the content of the discussion; but it does help keep clear who was posting to whom and when. :-) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tony Terlecki Sent: Saturday, June 08, 2002 7:46 AM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ? On Sat, Jun 08, 2002 at 09:43:00AM +0100, dickbo wrote: Bits equals available grey levels per pixel - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, June 07, 2002 4:22 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Just out of curiousity and in simple layman's terms, what do the number of bits that the converter has have to do with if not the density range? How does it impact on what is captured? Austin, I am asking a serious question here out of my lack of knowledge and sure would appreciate a good discussion in layman's terms so that I can understand what is being said without having to hire an engineer to interpret. It has always been my understanding, rightly or wrongly, that the higher the number of bits the more detailed or refined the informational date captured from the original that is transmitted as data in the digital file with respect to highlight and/or shadow detail with the density range figure representing the range of contrast that can be captured. In other words, dynamic range representing the contrast range of the capture's capabilities, while the bit depth represented the quality of the data captured within that range particularly the extremes. If this is wrong, please explain where and how it is and provide me with a more accurrate description (but once again, I urge you to try and do it in non-engineering terms if possible). The number of scanner bits is a necessary but not sufficient requirement for seeing densities at a scanner's theoretical dmax (i.e. log 2^bit-depth). Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. More importantly though the number of bits determine with what resolution the scanner can see the density levels that it is capable of scanning. Reread that last sentence again! Lets take a sample scanner which can only record film density up to a 2.4 dmax. This should be within the realms of even the cheapest modern film scanner hardware. This density limit is imposed by (let's say) the cheap design of the scanner and the manufacturer's requirements to be cost effective. Now lets take this scanner and give it an 8-bit CCD to start with. In a minute we'll give it a 14-bit CCD and see the difference. The number of bits represents the POTENTIAL density range that the scanner is capable of. Scanner CCDs are linear devices - it is important you understand this concept because it determines how well scanners can potentially see into the shadows. With a linear device each doubling or halving of a scanned linear data value represents a doubling or halving of light, or 1 stop, or 0.3 density units. Let us take our 8-bit scanner then - 8-bits gives us a total of 256 values that the scanner can use to scan the image. Let us look at the numbers to see how these data values can be spread out across a density range. I'm going to assume that the operator has placed the scanner's white point (value 255) exactly at the lightest portion of the film/paper. 128-255: 1 stop (0.3 density units) 64-127: 1 stop (0.3 density units) 32-63: 1 stop (0.3 density units) 16-31: 1 stop (0.3 density units) 8-15: 1 stop (0.3 density units) 4-7: 1 stop (0.3 density units) 2-3: 1 stop (0.3 density units) 0-1: 1 stop (0.3 density units) Note that I cannot go any further than this because I need at least two distinct values to represent a change in density. The 8-bit scanner then can scan up to 8 potential stops. It is impossible to see anything denser because it would need more bits. Even now you have so few bits at the shadow end that you would almost certainly have posturization. Let us move now to the same
[filmscanners] Re: Color spaces for different purposes
Sorry - I hadn't read this post when I sent the previous message. Perhaps you are over-sharpening? Also, are you sharpening just the Lightness channel or also the color channels? Maris - Original Message - From: Ken Durling [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:58 AM Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 11:56:29 -0500, you wrote: Theoretically maybe; but out of curiosity, how does one do this in actuality when one would have to first decompress the JPG file before one could carry out the sharpening operations. Afterwhich, one would then recompress the file again in its altered state which would be what typically causes the artifacts and deterioration in JPG files to begin with? Yes, I realized after I typed that what I actually do is resize the TIFF, edit, * sharpen * and THEN go to JPEG. It's in this resized TIFF that I see the increased sharpening or USM effects, over the raw intitial file. Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range
On Sat, Jun 08, 2002 at 10:42:39AM -0700, M. Denis Hill wrote: Now lets take this scanner and give it an 8-bit CCD to start with. In a minute we'll give it a 14-bit CCD and see the difference. Wouldn't that be an 8- (or 14) bit A/D converter, rather than CCD? In other words, are not CCDs analog devices providing voltages that are converted to digital representation? Yes you are completely right - I was confounding the two (or at least treating them as a single component). Denis Hill, QPP --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.362 / Virus Database: 199 - Release Date: 5/7/2002 -- Tony Terlecki [EMAIL PROTECTED] Running Debian/GNU 2.2 Linux Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
Yes - definitely TIFF for printing, but sharpen after you resize. I'm not familiar with Vuescan's for print output setting, since I output to PS anyway. Maris - Original Message - From: Ken Durling [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:55 AM Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 11:33:05 -0500, you wrote: Probably the artifacts created in the compression process. It would probably be better to convert to JPG first and then sharpen. But when printing it's best to go direct from the TIFF isn't it? This is where I run into it. When producing for the web, yes, I go to jpeg and then sharpen. Actually, I often resize the TIFF to the pixel size I want, do the rest of my editing and then sharpen just before converting to JPEG. I get good results this way.Come to think of it, I see a lot more sharpening effect when the TIFF has been resized than before - let alone the JPEG. I also haven't experimented with the for print output setting in Vuescan - any idea what this does differently? Ken Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Tony, The number of scanner bits is a necessary but not sufficient requirement for seeing densities at a scanner's theoretical dmax (i.e. log 2^bit-depth). Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. I've discussed my disagreement with this in another post... More importantly though the number of bits determine with what resolution the scanner can see the density levels that it is capable of scanning. That is correct, and the only thing number of bits is. It's called dynamic range. The number of bits represents the POTENTIAL density range that the scanner is capable of. And that's not right... Scanner CCDs are linear devices - it is important you understand this concept because it determines how well scanners can potentially see into the shadows. What is done in some scanners, is the analog output from the CCD to the A/D is adjusted (like a tonal curve) such that it boosts the ability of the scanner to see into the shadows, or any other parts for that matter. With a linear device each doubling or halving of a scanned linear data value represents a doubling or halving of light, or 1 stop, or 0.3 density units. But, as a note...don't confuse relative density units with absolute density values. Yes, two values from the scanner can be 2:1 relatively...but that does not say what the absolute density value of either of them is. Also, because the CCD is linear, does not mean that that the system doesn't have gain and offset... Let us take our 8-bit scanner then - 8-bits gives us a total of 256 values that the scanner can use to scan the image. Let us look at the numbers to see how these data values can be spread out across a density range. As I've said, there is no direct calibration/correlation between density range and data values. I can take the same density range, and spread it across ANY number of bits, or position it anywhere within any number of bits...it solely depends on the output characteristics of the CCD, as well as the analog front end between the CCD and the A/D. It is up to the CCDs sensitivity that determines what density range is presented to the analog front end, and then what the analog front end does with it before it gets to the A/D that determines what density range the A/D sees. I can take the exact same CCD that is used in a 14 bit scanner and put an 8 bit A/D in, and still get the exact same density range (less the lower 6 bits). I could also take your 8 bit scanner example, and simply put a 4 bit A/D, yet get the exact same density range out of it... I'm not speculating on this. I design digital imaging systems, and have been for 20 years. I've designed quite a few film scanners, and I know how they are designed, or at least how I've designed them ;-) One easy example to show that what you say is inaccurate, is that the density range of a 16 bit file, converted to an 8 bit file, is the same (except minus the lower 8 bits)...and the converse is true, you can take 8 bit data and convert it to 16 bit data, and it still represents the same density range. Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Austin, I find this conversation fascinating and hope you will stay the course with all my (possibly naiive responses.) I'm no expert at all but I have ideas that I thought were true and I'd like to work them through with you whatever the outcome... On Sat, Jun 08, 2002 at 01:18:17PM -0400, Austin Franklin wrote: Hi Tony, Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. Not true. You can represent ANY density by any number of bits. I can represent an entire density range with two bits: 00 - at or below dMin 10 or 01 - between dMin and dMax 10 - at or below dMax BTW, that should be at or ABOVE dMax...sorry. This is a completely valid encoding of density range. Sure it is. Is that what happens in a scanner though? I thought that the CCD behaved in a linear manner? Does that not dictate the encoding method somewhat? I have to run now, so I'll comment on the rest of your post later. Regards, Austin And...to add further to this, as I have a few moments... Density values are absolute values, just like one foot is an absolute value. They have meaning in and of them selves. Someone decided what the exact length of one foot is (within a tolerance of course), as well as density values. They mean the same thing everywhere...a density value of 1.6 means exactly that in La Jolla CA, as well as in Pascagoula, MS. Same with one foot. But, the tonal values out of a scanner are not the same everywhere, nor are they the same even between scans! The value 136 in La Jolla, CA...does not have the same tonality as the value 136 in Pascagoula, MS. Yep I agree with you here. That density values are absolute values. But relative density is also commonly used in film sensitometry is it not? Scanners are not calibrated TO anything, except themselves. That is why the data values you get from the scanner are not the same density values. There is no direct correlation between them, unless you were to calibrate your scanner in the same way densitometers are calibrated (even that is insufficient, as the sensors used in film scanners have different characteristics than the sensors used in densitometers). OK I have just bought a densitometer which lets me calibrate so that a 0 reading can be set to film base, then readings taken from there. Cannot the same be done for a scanner? If I scan a piece of film and the film base gives me a value of 248 (assume 8-bit here just for argument's sake) cannot I set that as my point from which all my other density values can be measured? Of course I am making an assumption that the data is behaving linearly (see http://www.bobwheeler.com/photo/Documents/ZoneDigital.pdf for an interesting article on this. I'd certainly like your opinion on whether the information presented seems feasible.) I may not know the absolute density reading but I would know the density range of the film I am scanning. If I were scanning a very dense piece of film (say Velvia) then I would need more than 8 bits to see well into those shadows would I not? Now, WHY would anyone in the first place say that number of bits has anything to do with density range...because they made some erroneous assumptions. Density range is stated in a ratio of to 1 (:1), and a density of 3.6 is 10**3.6:1 or 3981:1 (and someone, at some time, decided what the density value of 1 physically is), which the number 3981 requires 12 bits to represent in the binary system, if you are going to represent every integer value from 1 to 3981...BUT...that's the rub...a value of 3981 from the scanner is NOT the same as a density value of 3.6 (3981:1), for the reasons explained above. And, no, they are not close enough for government work ;-) Yes I agree with you here also but please see my comments above about relative density readings. Surely one is capable of determining relative density with one's own scanner? I've made some film charateristic curves using this method that seem reasonably good. -- Tony Terlecki [EMAIL PROTECTED] Running Debian/GNU 2.2 Linux Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: opinions? Reviews? of Primefilm 1800 ?
- Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 6:44 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Bits equals available grey levels per pixel That is nice; is this also true when one works in color as opposed to grayscale or black and white? Would I be wrong to generalize this and say bits equal potentially available tonal levels per pixel in which the tone can be any hue or color? That is corect except hue and colour mean the same thing However, the question in issue, I believe, was not the meaning of bits but if bit depth was intended to be a measure of dynamic range or of density range, of the contrast range from white point limit to black point limit or of the ability to discriminate between shades or tones within that contrast range, or more generally between the quantity of informational data regarding highlights and shadows and the quality of that information in terms of determining details precisely within that contrast range. That is a function of the imaging devices ability to see illumination levels of differing intensity. That is the original analogue signal. The bits come later. What you are really talking about is the electrical current being generated after the CCD has seen the illuminant. Once you have a current flowing somewhere you have something from which you can create bits or if you like post analogue is digital, by which I mean another device converts the analogue signal to a digital one. Depending on the current levels, so you have the devices original density range which, I would suggest is non linear in that for equal variations in illuminamnt you will not get a simlar variation in current except probably somewhere in the middle of the devices sensitivity range. At the highlight and shadow light levels the CCD will most likely be non linear, rather like film and paper emulsions. Photographic emulsions all have their linear response regions beyond which a non linear situation exists. In film the shadow areas are considered to be limited at that point where film base+fog density is equal to image density minus fog+base density. At the highlight end it is normally considered that where exposure increases offer no further increase in film density, then you have reached the limit of highlight detail. It is considered normal in electrical photo sensitive imaging devices, to assume that where random electrical noise equals image electrical output you will have reached the limits of image shadow response for any given imaging device. At the other highlight end where no further increase in current is generated. you have reached the upper limits of highlight reproduction. Please note we are talking negatives here baby doll. Bit depth therefore is the same for any particular original intensity level except that where device response limits are reached at both ends of the illumination intensity scale, having say 12 bits or 48 bits per colour channel will not enable you to see any more visual information because there is non to see, at least not once the illuminant has been digitised. Look at it this way: Suppose you have an original colour negative with a density range from 0.35-1.35. Let us say that there is a mid tone area around 0.9-1.0 density. For each colour you have 8 bits per tone level, that is each pixel can have any level between 0 up to 256 i.e.let us assume 256=white and 0=black. It is quite possible for any given area from either CYM image data to have it's pixel level edited to a number simlar to any other area of CYM level, and you will observe some tonal difference - or if you will, image making information - because the information is within the original devices electrical output range. At the two extreme ends however things are different because for example in the case of the shadow end there will be no further detail beyond 0 while at the highlight end nothing beyond 256. And that, as they say, is broadly how things work in digital imaging scanners. From the foregoing it would be reasonable to assume that in order to check any particular manufacturers clims regarding original density response range, it would be necessary to stick the kit under assesment into a properly equipmented lab employing properly qualified technicians. What you would probably find is that just as some lenses of the same mark and cars of the same model do not perform in exactly the same way, some scanners in a particular model range will out spec others in the same range which is why, when you read comments from respondents on this news group, you should be very careful not to assume a level of know-how that will never exceed their understanding and subjective opinions regarding their own particular item of equipment. As a final comment I would suggest that 16 years as a technical salesman for Crosfield Electronics taught me one certainty and that is that you will hardly ever find
[filmscanners] RE: Color spaces for different purposes
Alas, either I am misunderstanding you or I am terribly confused; both options are entirely possible. I would convert and sharpen before compressing If you convert any file format to a JPG format, are you not coverting and compressing at the same time? I did not think that in fact they are practically separate and distinct operations even if the act of coverting presents itself to the user as if it were being done in stages. Thus, if I am correct about the conversion and compression processes being from the users point of view for all intents and purposes one in the same, how does one sharpen between the conversion stage and the compression stage? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 1:07 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes I would convert and sharpen before compressing. It may or may not help - I'm not an expert - but it would deal with any artifacts that might possibly be introduced in the conversion process itself. I would not compress, re-open and recompress absent drastic sharpening artifacts in the compressed JPG. Maris - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:56 AM Subject: [filmscanners] RE: Color spaces for different purposes It would probably be better to convert to JPG first and then sharpen. Theoretically maybe; but out of curiosity, how does one do this in actuality when one would have to first decompress the JPG file before one could carry out the sharpening operations. Afterwhich, one would then recompress the file again in its altered state which would be what typically causes the artifacts and deterioration in JPG files to begin with? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 11:33 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes Probably the artifacts created in the compression process. It would probably be better to convert to JPG first and then sharpen. Maris - Original Message - From: Ken Durling [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 11:05 AM Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 16:17:30 +0100, you wrote: Personally I do some sharpening for an archival image that may end up going to different outputs. This is only a minor sharpening to restore the sharpness of the original which is almost always softened by the scanning process. Most images will benefit from further sharpening when targeting for a specific output but this should not really be done for an archival copy. Speaking of sharpening - I think I understand this in a sort of sloppy intuitive way, but could someone offer a technical explanation of why sharpening has so much more visible effect on jpegs as opposed to TIFFs? Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 -- -- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body -- -- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body -- -- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body -- -- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Color spaces for different purposes
Ok, that makes more sense to me now. However, since the sharpened JPG file upon opening by an user may then need to be resized and sharpening is dependent on the image size, you have a problem. It will then need to be resharpened for it new size which may result in artfacts being produced since you will be sharping an image that has already has sharpening done to it prior to compression. I would think it would be preferable and even wiser to leave the image unsharpened and convert it to a JPG file, leaving any sharpening to the user who opens the JPG file and determines how and at what size the image is to be reproduced to do after resizing the image to what is wanted and prior to reproduction. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Ken Durling Sent: Saturday, June 08, 2002 11:58 AM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes On Sat, 8 Jun 2002 11:56:29 -0500, you wrote: Theoretically maybe; but out of curiosity, how does one do this in actuality when one would have to first decompress the JPG file before one could carry out the sharpening operations. Afterwhich, one would then recompress the file again in its altered state which would be what typically causes the artifacts and deterioration in JPG files to begin with? Yes, I realized after I typed that what I actually do is resize the TIFF, edit, * sharpen * and THEN go to JPEG. It's in this resized TIFF that I see the increased sharpening or USM effects, over the raw intitial file. Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 -- -- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Color spaces for different purposes
At this point it's moot since Ken said he resizes in TIFF and sharpens, but I think you are correct - conversion from TIFF to JPG reduces file size and apparently compresses, I would think to Maximum quality. Sharpening at that point was what I was suggesting, before saving as a more-compressed JPG. Maris - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 3:35 PM Subject: [filmscanners] RE: Color spaces for different purposes Alas, either I am misunderstanding you or I am terribly confused; both options are entirely possible. I would convert and sharpen before compressing If you convert any file format to a JPG format, are you not coverting and compressing at the same time? I did not think that in fact they are practically separate and distinct operations even if the act of coverting presents itself to the user as if it were being done in stages. Thus, if I am correct about the conversion and compression processes being from the users point of view for all intents and purposes one in the same, how does one sharpen between the conversion stage and the compression stage? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 1:07 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes I would convert and sharpen before compressing. It may or may not help - I'm not an expert - but it would deal with any artifacts that might possibly be introduced in the conversion process itself. I would not compress, re-open and recompress absent drastic sharpening artifacts in the compressed JPG. Maris [remainder snipped] Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re:Polaroid sprintscan 4000 problems
I am using windows 98, firmware 1.4, which I downloaded about 3 weeks ago, pointing the temp files to a second hard drive with many Gb of space. I am using a stand alone version. Insight 5.5 would not start at all. I have been struggling with this for some time, and on the suspicion that there might be some conflicting software I have just reformatted the c: drive, (after getting very marginal improvements with lesser steps) and currently only have AOL and insight loaded on the machine. Unfortunately it is still very unstable. I will now try a completely clean install of Insight 5.5 Many thanks, Brian Boggenpoel. On Fri, 07 Jun 2002 03:28:33 -0700 Arthur Entlich [EMAIL PROTECTED] Wrote: I don't know the exact cause of your problem, and you didn't mention the platform you are using. Although your crashing is probably not caused by this, I would suggest you remove Insight 5.0 and upgrade to version 5.5, which has a few extra features (it is available on Polaroid's website). Also make sure you are upgraded to the latest firmware version. Then make sure that you are pointing the temp files to a location on your drive with lots of space. I suspect this will fix things. If not, please provide us with some additional info (like platform, where the files are being written to, if you are using the Photoshop TWAIN interface or the stand alone version, etc.) Art brian boggenpoel wrote: Can anyone advise, or point me in the right direction regarding a problem with a Polaroid sprintscan 4000. I have plenty of RAM, and diskspace, but the software (Insight ver 5.0) is very unstable, and usually crashes every second scan. Many thanks, Brian Boggenpoel. _ Chat with friends online, try MSN Messenger: http://messenger.msn.com Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: Re:Polaroid sprintscan 4000 problems
This could point to a PC hardware problem. Can you load the software on an other PC and check if that is also unstable when using the scanner. Sometimes RAM and Motherboard problems just happen at the worst of times. You have loaded the latest video drivers available I assume. Eddie - Original Message - From: brian boggenpoel [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 10:43 PM Subject: [filmscanners] Re:Polaroid sprintscan 4000 problems I am using windows 98, firmware 1.4, which I downloaded about 3 weeks ago, pointing the temp files to a second hard drive with many Gb of space. I am using a stand alone version. Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
I find this conversation fascinating and hope you will stay the course with all my (possibly naiive responses.) I'm no expert at all but I have ideas that I thought were true and I'd like to work them through with you whatever the outcome... Hi Tony, I'll do my best ;-) On Sat, Jun 08, 2002 at 01:18:17PM -0400, Austin Franklin wrote: Hi Tony, Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. Not true. You can represent ANY density by any number of bits. I can represent an entire density range with two bits: 00 - at or below dMin 10 or 01 - between dMin and dMax 10 - at or below dMax BTW, that should be at or ABOVE dMax...sorry. This is a completely valid encoding of density range. Sure it is. Great start ;-) Is that what happens in a scanner though? The major point is, though they MAY be somewhat similar, they are not the same. They they is density values and the numbers you get out of the scanner. IF the scanner were calibrated, as densitometers are (but more complexly), one could make them close enough to be considered the same, but no commercially available scanner I am aware of does this. I thought that the CCD behaved in a linear manner? Yes, but relative only unto it self! Does that not dictate the encoding method somewhat? Well, the linearity doesn't, but, the sensitivity does. If the CCD outputs +-1V and has a noise level of .001V, then you would have 2/.001 or 2000 discrete values you needed to discern, and would need 10 bits...but that's dynamic range, NOT density range. The density range of the sensor is what ever it is...again, part of the sensor's spec. I have to run now, so I'll comment on the rest of your post later. Regards, Austin And...to add further to this, as I have a few moments... Density values are absolute values, just like one foot is an absolute value. They have meaning in and of them selves. Someone decided what the exact length of one foot is (within a tolerance of course), as well as density values. They mean the same thing everywhere...a density value of 1.6 means exactly that in La Jolla CA, as well as in Pascagoula, MS. Same with one foot. But, the tonal values out of a scanner are not the same everywhere, nor are they the same even between scans! The value 136 in La Jolla, CA...does not have the same tonality as the value 136 in Pascagoula, MS. Yep I agree with you here. That density values are absolute values. But relative density is also commonly used in film sensitometry is it not? Yes...but I don't see how that ties into us here. Again, the scanner isn't calibrated, and dMax and dMin values ARE calibrated/absolute values... Scanners are not calibrated TO anything, except themselves. That is why the data values you get from the scanner are not the same density values. There is no direct correlation between them, unless you were to calibrate your scanner in the same way densitometers are calibrated (even that is insufficient, as the sensors used in film scanners have different characteristics than the sensors used in densitometers). OK I have just bought a densitometer which lets me calibrate so that a 0 reading can be set to film base, then readings taken from there. Cannot the same be done for a scanner? Yes, but that has nothing to do with dMax and dMin...with respect to any other scanner, and comparing scanners. You can't say that film has a dMax of X when measuring in that mode, you can only say it has a relative density value of Y compared to the film base. If I scan a piece of film and the film base gives me a value of 248 (assume 8-bit here just for argument's sake) cannot I set that as my point from which all my other density values can be measured? Yes, but again, that doesn't relate back to absolute density values... I may not know the absolute density reading but I would know the density range of the film I am scanning. But comparing that to another scanner would be meaningless... You would have a density range, sort of...simply because a density range of 1 to 2 is the same relatively as 2 to 4, but obviously, 4 is one heck of a lot denser than 2. If I were scanning a very dense piece of film (say Velvia) then I would need more than 8 bits to see well into those shadows would I not? No. I can design a scanner (and have) that only uses 4 bits to encode the entire range from 0 to 4. It just has no resolution (dynamic range). Think about line art. It has high density range, but no tonality...and you don't need more than 1 bit to encode it ;-) Surely one is capable of determining relative density with one's own scanner? Not accurately, unless, as I said, you calibrated it. You need to calibrate for offset, gain
[filmscanners] RE: opinions? Reviews? of Primefilm 1800 ?
Depending on the current levels, so you have the devices original density range which, I would suggest is non linear in that for equal variations in illuminamnt you will not get a simlar variation in current except probably somewhere in the middle of the devices sensitivity range. At the highlight and shadow light levels the CCD will most likely be non linear, rather like film and paper emulsions. Dickbo, You can suggest that, but it's not true. Go take a look at some CCD data sheet and check the linearity curve. The Kodak 14400 has a linearity from 0-100% (35 electrons to 230,000) of +-1%. It looks nothing like a film curve I have seen. It's simply a low slope upward curve starting at 0 (with a little dip), going up to .6% at the %50 point and back down to 0 at the %85 point and then going to -1 at the %100 point. It is considered normal in electrical photo sensitive imaging devices, to assume that where random electrical noise equals image electrical output you will have reached the limits of image shadow response for any given imaging device. At the other highlight end where no further increase in current is generated. you have reached the upper limits of highlight reproduction. Please note we are talking negatives here baby doll. That's all well and good, but that is very dependant on ILLUMINATION. Bit depth therefore is the same for any particular original intensity level except that where device response limits are reached at both ends of the illumination intensity scale, having say 12 bits or 48 bits per colour channel will not enable you to see any more visual information because there is non to see, at least not once the illuminant has been digitised. That depends on the design of the scanner. Again, illumination intensity AND exposure time play a very important factor in this. And that, as they say, is broadly how things work in digital imaging scanners. VERY broadly...and loosely. There is a lot missing. Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: opinions? Reviews? of Primefilm 1800 ?
That is corect except hue and colour mean the same thing That is why I used the term or rather than and; I thought I would give you a choice. :-) As for the rest of your comments, thank you; they were more along the lines of what I was seeking. Although a bit more technical than I had hoped for, I found them informative. From those parts that I do comprehend, I believe that my understanding concurs with what you are saying in terms of the general ideas if not the specific details; and what you are saying is similar to what Austin has said. Once again thanks for taking the time to respond. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of dickbo Sent: Saturday, June 08, 2002 3:45 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: opinions? Reviews? of Primefilm 1800 ? - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 6:44 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Bits equals available grey levels per pixel That is nice; is this also true when one works in color as opposed to grayscale or black and white? Would I be wrong to generalize this and say bits equal potentially available tonal levels per pixel in which the tone can be any hue or color? That is corect except hue and colour mean the same thing However, the question in issue, I believe, was not the meaning of bits but if bit depth was intended to be a measure of dynamic range or of density range, of the contrast range from white point limit to black point limit or of the ability to discriminate between shades or tones within that contrast range, or more generally between the quantity of informational data regarding highlights and shadows and the quality of that information in terms of determining details precisely within that contrast range. That is a function of the imaging devices ability to see illumination levels of differing intensity. That is the original analogue signal. The bits come later. What you are really talking about is the electrical current being generated after the CCD has seen the illuminant. Once you have a current flowing somewhere you have something from which you can create bits or if you like post analogue is digital, by which I mean another device converts the analogue signal to a digital one. Depending on the current levels, so you have the devices original density range which, I would suggest is non linear in that for equal variations in illuminamnt you will not get a simlar variation in current except probably somewhere in the middle of the devices sensitivity range. At the highlight and shadow light levels the CCD will most likely be non linear, rather like film and paper emulsions. Photographic emulsions all have their linear response regions beyond which a non linear situation exists. In film the shadow areas are considered to be limited at that point where film base+fog density is equal to image density minus fog+base density. At the highlight end it is normally considered that where exposure increases offer no further increase in film density, then you have reached the limit of highlight detail. It is considered normal in electrical photo sensitive imaging devices, to assume that where random electrical noise equals image electrical output you will have reached the limits of image shadow response for any given imaging device. At the other highlight end where no further increase in current is generated. you have reached the upper limits of highlight reproduction. Please note we are talking negatives here baby doll. Bit depth therefore is the same for any particular original intensity level except that where device response limits are reached at both ends of the illumination intensity scale, having say 12 bits or 48 bits per colour channel will not enable you to see any more visual information because there is non to see, at least not once the illuminant has been digitised. Look at it this way: Suppose you have an original colour negative with a density range from 0.35-1.35. Let us say that there is a mid tone area around 0.9-1.0 density. For each colour you have 8 bits per tone level, that is each pixel can have any level between 0 up to 256 i.e.let us assume 256=white and 0=black. It is quite possible for any given area from either CYM image data to have it's pixel level edited to a number simlar to any other area of CYM level, and you will observe some tonal difference - or if you will, image making information - because the information is within the original devices electrical output range. At the two extreme ends however things are different because for example in the case of the shadow end there will be no further detail beyond 0 while at the highlight end nothing beyond 256. And that, as they say, is broadly how things work in digital imaging scanners. From the foregoing it would be reasonable to assume that in order to check any particular
[filmscanners] RE: Color spaces for different purposes
At this point it's moot True, especially with regard to the original basis for the discussion. :-) However, it may not be moot with respect to spin-off issues. :-) conversion from TIFF to JPG reduces file size and apparently compresses, I would think to Maximum quality. Sharpening at that point was what I was suggesting, before saving as a more-compressed JPG Saving a file as a JPG file at a level of compression involving the least amount of compression would obviously result in much less lost empirical information (e.g., actual image data) than to save at higher compression levels; however, I think it is questionable if the remaining empirical data would represent maximum quality in all cases. But to change the existing data in the original JPG file by sharpening and then resaving the result to a more compressed state is one of the sorts of actions which tends to produce the often found JPG artifacts and deterioration of the image that such a file can produce. Obviously, the more often one changes the level of compression in the resaving of an openned JPG file as well as the more information that one changes between such compressions the greater the possibility of artifacts and deterioration of the resulting image. At least, as far as the earlier versions of JPG ( cannot speak for JPG 2000), the compression was a lossy operation in which algorithms were used during compression to discard redundant data and to generate new data based on the retained data and the algorithm upon expanding the file. To recompress at a new level means that one would be applying the algorithm to increased levels of artificially created simulated data with each such resaving at a different level. Thus, the net result would be to be creating or interpolating new data based on existing data that itself was artifically created by a similar method with less and less of the data that makes up the file being the original data from the capture. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 4:40 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes At this point it's moot since Ken said he resizes in TIFF and sharpens, but I think you are correct - conversion from TIFF to JPG reduces file size and apparently compresses, I would think to Maximum quality. Sharpening at that point was what I was suggesting, before saving as a more-compressed JPG. Maris - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 3:35 PM Subject: [filmscanners] RE: Color spaces for different purposes Alas, either I am misunderstanding you or I am terribly confused; both options are entirely possible. I would convert and sharpen before compressing If you convert any file format to a JPG format, are you not coverting and compressing at the same time? I did not think that in fact they are practically separate and distinct operations even if the act of coverting presents itself to the user as if it were being done in stages. Thus, if I am correct about the conversion and compression processes being from the users point of view for all intents and purposes one in the same, how does one sharpen between the conversion stage and the compression stage? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Maris V. Lidaka Sr. Sent: Saturday, June 08, 2002 1:07 PM To: [EMAIL PROTECTED] Subject: [filmscanners] Re: Color spaces for different purposes I would convert and sharpen before compressing. It may or may not help - I'm not an expert - but it would deal with any artifacts that might possibly be introduced in the conversion process itself. I would not compress, re-open and recompress absent drastic sharpening artifacts in the compressed JPG. Maris [remainder snipped] Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Density values are absolute values, just like one foot is an absolute value. They have meaning in and of them selves. Someone decided what the exact length of one foot is (within a tolerance of course), as well as density values. Just as a point of levity did not Einstein's theory of relativity call the notion that a foot would be the same under all circumstances in all locations (i.e. a universal absolute)? If so, why would it not apply to the lowly density measure as well as the foot as a unit of measure? :-) -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Austin Franklin Sent: Saturday, June 08, 2002 12:18 PM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ? Hi Tony, Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were up to scratch and could use those bits to their full. Not true. You can represent ANY density by any number of bits. I can represent an entire density range with two bits: 00 - at or below dMin 10 or 01 - between dMin and dMax 10 - at or below dMax BTW, that should be at or ABOVE dMax...sorry. This is a completely valid encoding of density range. I have to run now, so I'll comment on the rest of your post later. Regards, Austin And...to add further to this, as I have a few moments... Density values are absolute values, just like one foot is an absolute value. They have meaning in and of them selves. Someone decided what the exact length of one foot is (within a tolerance of course), as well as density values. They mean the same thing everywhere...a density value of 1.6 means exactly that in La Jolla CA, as well as in Pascagoula, MS. Same with one foot. But, the tonal values out of a scanner are not the same everywhere, nor are they the same even between scans! The value 136 in La Jolla, CA...does not have the same tonality as the value 136 in Pascagoula, MS. Scanners are not calibrated TO anything, except themselves. That is why the data values you get from the scanner are not the same density values. There is no direct correlation between them, unless you were to calibrate your scanner in the same way densitometers are calibrated (even that is insufficient, as the sensors used in film scanners have different characteristics than the sensors used in densitometers). Now, WHY would anyone in the first place say that number of bits has anything to do with density range...because they made some erroneous assumptions. Density range is stated in a ratio of to 1 (:1), and a density of 3.6 is 10**3.6:1 or 3981:1 (and someone, at some time, decided what the density value of 1 physically is), which the number 3981 requires 12 bits to represent in the binary system, if you are going to represent every integer value from 1 to 3981...BUT...that's the rub...a value of 3981 from the scanner is NOT the same as a density value of 3.6 (3981:1), for the reasons explained above. And, no, they are not close enough for government work ;-) Regards, Austin Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: JPG sharpening [was: Color spaces for different purposes]
True enough, but if the image requires sharpening? JPG is not a good format, I know, but it is very useful and in fact necessary for the web. I would think it better to convert to JPG and then sharpen rather than sharpen in TIFF and then convert. I haven't tested but I think it would result in fewer artifacts. Maris - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Saturday, June 08, 2002 8:34 PM Subject: [filmscanners] RE: Color spaces for different purposes [snipped] conversion from TIFF to JPG reduces file size and apparently compresses, I would think to Maximum quality. Sharpening at that point was what I was suggesting, before saving as a more-compressed JPG Saving a file as a JPG file at a level of compression involving the least amount of compression would obviously result in much less lost empirical information (e.g., actual image data) than to save at higher compression levels; however, I think it is questionable if the remaining empirical data would represent maximum quality in all cases. But to change the existing data in the original JPG file by sharpening and then resaving the result to a more compressed state is one of the sorts of actions which tends to produce the often found JPG artifacts and deterioration of the image that such a file can produce. [remainder snipped] Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] Re: JPG sharpening [was: Color spaces for different purposes]
On Sat, 8 Jun 2002 21:36:38 -0500, you wrote: True enough, but if the image requires sharpening? JPG is not a good format, I know, but it is very useful and in fact necessary for the web. I would think it better to convert to JPG and then sharpen rather than sharpen in TIFF and then convert. I haven't tested but I think it would result in fewer artifacts. Well there may be other variables in my system, but I get fewer artifacts sharpening the reduced TIFF rather than the JPEG. I may need to experiment with lower USM settings on my JPEGs, but given my scanner's good somewhat limited capabilities (FS2710) , I'm very happy with the workflow of TIFFresize/resample sharpencompress. Ken Durling Visit my new easier-to-browse PhotoSIG portfolio: http://www.photosig.com/viewuser.php?id=203 Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
[filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ?
Tony, Number of bits have two main roles. They do indeed represent the theoretical maximum density that a scanner could have if the electrical components were .up to scratch and could use those bits to their full. More importantly though the number of bits determine with what resolution the scanner can see the density levels that it is capable of scanning. Reread that last sentence again! Neither of the two points that are made, as I understand them, fits with my understandings. Under ideal conditions all things being equal, my understanding is that the bit depth if all those bits are capable of being used by the device at full capacity do not represent the maximum density that a scanner can have but the maximum ability of that scanner to capture in digital terms the details or discriminate between tonality at along the density range continuum (i.e., the dynamic range which the scanner can capture and digitalize within its desnity range) Namely, whether, in a denisty range from 0 to 100, the scanner can digitally discriminate between 10 discrete steps or 100 discrete steps. With respect to point two, it is not my understanding that the bit depth of a scanner has anything to do with the resolution that the scanner can see or read the density levels unless, of course, you mean by resolution the ability to make qualitative descriminations between different density levels or contrast steps within the contrast range or density range capable of being captured and digitalized by the device. The number of bits represents the POTENTIAL density range that the scanner is capable of. Scanner CCDs are linear devices I take issue with the statement that the number of bits represents the potential density range. Dynamic range yes; density range no. Secondly, I am not an engineer so I do not know for certain; but are we really talking about the CCDs or the DC converter when we speak of linear devices in relation to bit depth. Moreover, are either of them really linear devices in actuality? Let us take our 8-bit scanner then - 8-bits gives us a total of 256 values that the scanner can use to scan the image Are we really saying that the 8-bits are defining a density range of 256 equal units length from Dmin to Dmax as if this were a dimensional measure or that 8-bits are capable of breaking a density range of any dimensionality into 256 different, discretely defined sections as opposed to breaking the same density range into say 100 different descretely defined sections. For purposes of argument and because I lack the knowledge to say otherwise, I am willing to assume that the segments are identical equal interval segments and not ratio interval or non-equal interval segments of variying sizes, although that might also be theoretically problematic. It's difficult describing this purely in layman's terms. If you don't understand anything here then please say so and I'm sure we can elaborate/simplify further. I understand the gist of your argument and explanation; but I am having trouble following the details or knowing enough to raise appropriate arguments or questions concerning the details or the conclusions you have drawn from them. I must say that the exchange between you and Austin and Austin and others on the subject has sort of gotten beyond my ability to comment on with respect to technical details and arguments. I am going to sit back and listen to the discussion, asking questions or raising issues in an attemt to make sense out of what is being said and why. I apologize in advance if I sound confused or way off base. I do appreciate everyone's help in my attempt to clarify things. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of Tony Terlecki Sent: Saturday, June 08, 2002 7:46 AM To: [EMAIL PROTECTED] Subject: [filmscanners] RE: Density vs Dynamic range - was: RE: opinions? Reviews? of Primefilm 1800 ? On Sat, Jun 08, 2002 at 09:43:00AM +0100, dickbo wrote: Bits equals available grey levels per pixel - Original Message - From: Laurie Solomon [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Friday, June 07, 2002 4:22 PM Subject: [filmscanners] RE: opinions? Reviews? of Primefilm 1800 ? Another misconception...though equally as common...the number of bits the converter has, have nothing to do with the scanners ability to capture any particular density range. Just out of curiousity and in simple layman's terms, what do the number of bits that the converter has have to do with if not the density range? How does it impact on what is captured? Austin, I am asking a serious question here out of my lack of knowledge and sure would appreciate a good discussion in layman's terms so that I can understand what is being said without having to hire an engineer to interpret. It has always been my understanding, rightly or wrongly, that the higher the number of bits the more detailed or refined the informational date captured from the
