[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] 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: 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: 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: 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
