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Thread: Software for Converting Scanned Color Negatives

  1. #41

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    Re: Software for Converting Scanned Color Negatives

    In my opinion, each scan must contain unexposed film borders. Such areas will make for true Dark point.
    White point and neutral Gray is always a challenge if the scanned image does not contain such colors in it. But there must be a formula that allows to reliably calculate the proper values for each of these just based on the value of exposed area. It is done when printed optically and it is repeatable, hence there must be formula for each emulsion, exposure (under, normal, over) and development (push, normal, pull) combo.
    From my countless experiments with scans of color negatives in PS, I have a feeling that RGB curves when used to set Dark and White points wreck highlights.
    LAB might be a more suitable color space for the conversion. At least in PS.

  2. #42
    Alan Klein's Avatar
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    Re: Software for Converting Scanned Color Negatives

    Quote Originally Posted by SergeyT View Post
    In my opinion, each scan must contain unexposed film borders. Such areas will make for true Dark point.
    White point and neutral Gray is always a challenge if the scanned image does not contain such colors in it. But there must be a formula that allows to reliably calculate the proper values for each of these just based on the value of exposed area. It is done when printed optically and it is repeatable, hence there must be formula for each emulsion, exposure (under, normal, over) and development (push, normal, pull) combo.
    From my countless experiments with scans of color negatives in PS, I have a feeling that RGB curves when used to set Dark and White points wreck highlights.
    LAB might be a more suitable color space for the conversion. At least in PS.
    What about using Levels?

  3. #43
    Alan Klein's Avatar
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    Re: Software for Converting Scanned Color Negatives

    Can anyone explain in simple terms in 25 words or less the orange mask's purpose and why it creates problems when scanning?

  4. #44
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    Re: Software for Converting Scanned Color Negatives

    Some info:

    (It’s more than twenty five words, but worth the read!)

    http://www.brianpritchard.com/why_co..._is_orange.htm

  5. #45
    Alan Klein's Avatar
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    Re: Software for Converting Scanned Color Negatives

    Thanks, a little complicated. I found this explanation of why scanners are better wth orange masks than shooting them with a digital camera. Can anyone explain how a scanner does the following (bolded) from the article?

    Color negatives are a special problem to remove the orange mask. Film scanners scan color negatives with a longer exposure time of the blue and green channels. This acts as an analog glass filter at the lens, and the longer exposure boosts the blue and green components and reduces the orange (as an analog operation, similar to a glass filter). Otherwise, if not filtered, then when inverted, the color negative mask appears near deep blue (the complement of light orange) instead of the correct colors.
    https://www.scantips.com/colornegs.html

  6. #46
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    Re: Software for Converting Scanned Color Negatives

    I did find this source of information:

    https://www.scantips.com/colornegs.html

    Decades ago, I printed color slides using a Unicolor drum. Then I would print client selected slides to make a wedding album. I would usually have them over.to my home for a fondue party and slide show! This was the 70’s. Looking.back it was really a pita.

    I have a color analyzer to use with my Omega enlarger.

    I did some C-41 processing but mostly had all this done by a lab for me. I was too busy! And, quite frankly, I’m using my creative skills and energy at a high level with photoshop. Monte Zucker and Eddie Tapp really sparked my brain learning about this program. It’s really quite simple.

    So my knowledge on processing color film is limited. Thank goodness!

    Since I’m a nerd with this, when photography went digital, I understood it and loved it. Why, now, I could sell and have made very large enlargements. My largest sale was a 50” by 40” print. Fantastic.

    So I hope you get your arms around this subject. Do you process your own materials with your own darkroom?

    At any rate, keep google searching. I’m doing some now that you peaked my interest!

    I had a large store of Kodak color paper (up to 16x20) and Kodak chemicals that I gave away.

    If folks are interested, I could write several chapters on people photography. My avitar was made sometime ago in Sarasota Florida by a gent named Monte Zucker. He was my coach and friend.

    If I’m not committing a sin here, my belief is digital is the only way to go. Sorry!

  7. #47

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    Re: Software for Converting Scanned Color Negatives

    Quote Originally Posted by Alan Klein View Post
    Thanks, a little complicated. I found this explanation of why scanners are better wth orange masks than shooting them with a digital camera. Can anyone explain how a scanner does the following (bolded) from the article?

    Color negatives are a special problem to remove the orange mask. Film scanners scan color negatives with a longer exposure time of the blue and green channels. This acts as an analog glass filter at the lens, and the longer exposure boosts the blue and green components and reduces the orange (as an analog operation, similar to a glass filter). Otherwise, if not filtered, then when inverted, the color negative mask appears near deep blue (the complement of light orange) instead of the correct colors.
    https://www.scantips.com/colornegs.html
    Hm, a filmscanner varying exposure times of different colors is quite false and the rest of that post too.
    Im sorry but I have to remind what a scanner does. If a scanner (like the Epson 700/800s) has the technical specs of density 4D and 16bit/channel recording, this means: the scanner has a brightness latitude 1:10000 (=4D) which is about 13 f-stops, and within this value the brightness is scaled in about 65000 steps (16bit) from black to white, for each (!) color RGB.
    After calibrating the lightsource (brightness and color of the lamp) the scanner makes a scan of the picture within his complete brightness room and renders this to 16bit, no matter you have a BW, Colorslide, oder Colorneg on the scanner, and no matter of your manual or auto adjstments in BW-Points, Brighness and Colors and else.
    All this is the second step made not by the scanner, but by computing of the scanner software. This first step is the famous rawscan and as it is completely untouched, there cannot be any wrong adjustments (but also not any right). The scanning with all the three or six scanning rows for each colour is one single step, inherent is no technical possibility to vary exposure or filtering one color separately.
    You can verify or falsify my statement: If the time of the raw scanning (when you hear scanner-motor working) is the same despite varying brighness, color balance or color reversal, but scanning time is varying setting dpi much higher (from 2400 to 6400) or lower, that will prove my theory.

    Short results:
    Extracting a CN rawscan is not faulty, but a correct way to digitize CN-Film.
    Extracting the mask can be done within the scanning software, or also later in PS.
    Pretuning the scan in scanning software and finetuning later in PS is quite right (this is my way).
    Digitizing NC via a Camera is possible with the correct technical equipment and workflow

    regards
    Rainer
    Last edited by rawitz; 16-May-2022 at 04:59.

  8. #48
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    Re: Software for Converting Scanned Color Negatives

    Quote Originally Posted by rawitz View Post
    Hm, a filmscanner varying exposure times of different colors is quite false and the rest of that post too.
    Im sorry but I have to remind what a scanner does. If a scanner (like the Epson 700/800s) has the technical specs of density 4D and 16bit/channel recording, this means: the scanner has a brightness latitude 1:1000 (=4D) which is about 10 f-stops, and within this value the brightness is scaled in about 65000 steps (16bit) from black to white, for each (!) color RGB.
    After calibrating the lightsource (brightness and color of the lamp) the scanner makes a scan of the picture within his complete brightness room and renders this to 16bit, no matter you have a BW, Colorslide, oder Colorneg on the scanner, and no matter of your manual or auto adjstments in BW-Points, Brighness and Colors and else.
    All this is the second step made not by the scanner, but by computing of the scanner software. This first step is the famous rawscan and as it is completely untouched, there cannot be any wrong adjustments (but also not any right). The scanning with all the three or six scanning rows for each colour is one single step, inherent is no technical possibility to vary exposure or filtering one color separately.
    You can verify or falsify my statement: If the time of the raw scanning (when you hear scanner-motor working) is the same despite varying brighness, color balance or color reversal, but scanning time is varying setting dpi much higher (from 2400 to 6400) or lower, that will prove my theory.

    Short results:
    Extracting a CN rawscan is not faulty, but a correct way to digitize CN-Film.
    Extracting the mask can be done within the scanning software, or also later in PS.
    Pretuning the scan in scanning software and finetuning later in PS is quite right (this is my way).
    Digitizing NC via a Camera is possible with the correct technical equipment and workflow

    regards
    Rainer
    Rainer, MAybe you can clarify something that I haven't been able too. Some people have said you ought to set the white and black points before the scan by setting them on the scanner's prescan histogram where the picture data starts and ends. The alternative is to scan "flat" 0-255 and adjust these points (levels) in post editing program. The former gives you more data to work with.

    I've tried it both ways and I haven't seen a difference in data quantity or type between the two methods. What is the reality of these methods? (i'm not referring to negative film vs chromes but this question applies to both types of films.)

    Also, what do you mean by "pretuning"?

  9. #49

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    Re: Software for Converting Scanned Color Negatives

    Quote Originally Posted by Alan Klein View Post
    Rainer, MAybe you can clarify something that I haven't been able too. Some people have said you ought to set the white and black points before the scan by setting them on the scanner's prescan histogram where the picture data starts and ends. The alternative is to scan "flat" 0-255 and adjust these points (levels) in post editing program. The former gives you more data to work with.

    I've tried it both ways and I haven't seen a difference in data quantity or type between the two methods. What is the reality of these methods? (i'm not referring to negative film vs chromes but this question applies to both types of films.)

    Also, what do you mean by "pretuning"?
    I start to answer your question from an unexspected side. As said above the scanner can only work within his absolute working-room of (here) 4d and 16bit. Its a common error to think by setting special BW-Points and narrowing the histogramm, its possible to get a enhanced 16-rawscan of the narrowed space. No! No matter of your presets in software
    1.first there is the rawscan over the full technical 4d space with 16bit.
    2.the software adjustment step will then (!) cut out your selected picture-space of the rawscan, and so you will cut-off and loose bit-values in the unused space. Its the software, that recalculates the (from raw) reduced Bit-Space in your now upscaled 48bit output. Exept of rawscan so you never get a (scan)native 48bit pic for output.
    And Alan, this means, you loose native colorspace in your presetting the scan in scanning-software (no matter your output setting). Or your rawscan is native 16bit but while tuning in software later, its THE SAME LOSS" if you result in the same final picture. And because all this pre- while- and after-tuning doesnt make any difference if you have the same final pic, my personal way in scanning BW,Slide and CN is:
    Pretune within the scanning software by setting BW-Points with "some room" to the left and right of the histogramm, also the brightness and color-setting, and while finetuning later in PS I will never have BW- or colorspace cutoff, thats a complete ruin of your work.

    regards
    Rainer
    Last edited by rawitz; 15-May-2022 at 09:20.

  10. #50
    Alan Klein's Avatar
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    Re: Software for Converting Scanned Color Negatives

    Quote Originally Posted by rawitz View Post
    I start to answer your question from an unexspected side. As said above the scanner can only work within his absolute working-room of (here) 4d and 16bit. Its a common error to think by setting special BW-Points and narrowing the histogramm, its possible to get a double 16-rawscan. No - no matter of your presets in software
    1.first there is the rawscan over the full technical 4d space with 16bit.
    2.the software adjustment step will then (!) cut out your selected picture-space of the rawscan, and so you will cut-off and loose bit-values in the unused space. Its the software, that recalculates the (from raw) reduced Bit-Space in your now upscaled 48bit output. Exept of rawscan so you never get a (scan)native 48bit pic for output.
    And Alan, this means, you loose native colorspace in your presetting the scan in scanning-software (no matter your output setting). Or your rawscan is native 16bit but while tuning in software later, its THE SAME LOSS" if you result in the same final picture. And because all this pre- while- and after-tuning doesnt make any difference if you have the same final pic, my personal way in scanning BW,Slide and CN is:
    Pretune within the scanning software by setting BW-Points with "some room" to the left and right of the histogramm, also the brightness and color-setting, and while finetuning later in PS I will never have BW- or colorspace cutoff, thats a complete ruin of your work.

    regards
    Rainer
    It's not totally clear. Do you get more workable data setting the histogram before the scan or not?

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