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Thread: Converting Photo Negative to Positive

  1. #1
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    Question Converting Photo Negative to Positive

    I am looking for Linux software with a GUI frontend that can convert a negative (tiff, png, jpg) into a viewable positive photograph that can then be edited or printed.

    Is there such a thing?

  2. #2
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    Re: Converting Photo Negative to Positive

    You just invert the image.

    Gimp will do this easily enough (i'll check the shortcut when I get home). on photoshop it's CTRL+I, so I can't imagine Gimp being any different.

    I'm starting a project on Wednesday photographing some early 1900s glass negatives. so I've checked that this works!

  3. #3

    Re: Converting Photo Negative to Positive

    Just inverting the image will not always suffice. That's because a photographic color negative is not simply a mathematical color inversion. On commercial systems (Windows and Mac) software for scanning negatives will have a number of lookup tables for proper color correction, if you know the film that was used.

    However, I doubt if you need "industry standard" colors, just whatever looks good. So, using gimp, use Colors > Invert, then Colors > Auto > White Balance. From there, you should be able to make manual color adjustments to your taste. EDIT: This does not work as well as expected.
    Last edited by Rallg; March 24th, 2009 at 09:38 PM.

  4. #4
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    Unhappy Re: Converting Photo Negative to Positive

    Quote Originally Posted by everytimeref View Post
    You just invert the image.

    Gimp will do this easily enough (i'll check the shortcut when I get home). on photoshop it's CTRL+I, so I can't imagine Gimp being any different.

    I'm starting a project on Wednesday photographing some early 1900s glass negatives. so I've checked that this works!
    It did not work. I scanned in the negative. When I opened it in Gimp it was the characteristic orange color negative. After invert it still looked like a negative but it was cyan looking.

  5. #5

    Re: Converting Photo Negative to Positive

    Indeed, inverting a standard color negative (which usually has orange mask) will result in a blue or cyan cast to the positive. Commerical scanning software (for Windows or mac) knows this, and corrects by film type. Old glass negatives may not use that technology.

    Again, I suggest using auto white balance as a starting point.

  6. #6
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    Question Re: Converting Photo Negative to Positive

    Quote Originally Posted by Rallg View Post
    Indeed, inverting a standard color negative (which usually has orange mask) will result in a blue or cyan cast to the positive. Commerical scanning software (for Windows or mac) knows this, and corrects by film type. Old glass negatives may not use that technology.

    Again, I suggest using auto white balance as a starting point.
    Here is what I did and the result:

    1. Opened the orange negative in Gimp

    2. Color>Invert
    Got a cyan looking negative

    3. Did a Color>Auto>White Balance
    Nothing visual happened


    I really do not know what to do. Even if something worked it would not be practical to do this on a hundred scans when using the Windows Epson software works in this particular case.

    While I do not favor Windows I am thinking about using virtualbox on a Linux host with Windows and scanning software as a Guest.

    I think that this should be added to XSane and made that suggestion but who knows if it was heard.

  7. #7
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    Re: Converting Photo Negative to Positive

    My copy of xsane lists nine different types of negatives, including "standard," "agfa," and "kodak." Perhaps these are handled in the backend code rather than in xsane itself...
    --
    Jim Kyle in Oklahoma, USA
    Linux Counter #259718
    Howto mark thread: https://wiki.ubuntu.com/UnansweredPo.../SolvedThreads

  8. #8

    Re: Converting Photo Negative to Positive

    If auto white balance did not help...

    First, look at JKyleOKC's comment, above. That might be useful.

    EDIT: If your browse the Internet, you will see that your question is often discussed (Window/Mac), with solutions using Photoshop for those who don't have scanner color correction. The various techniques used for Photoshop can also be done with Gimp.

    Based on comments elsewhere, it seems that the best approach (if you don't have scanner color correction) is to apply auto levels to each color channel separately, then make final adjustments to the combined image.
    Last edited by Rallg; March 24th, 2009 at 09:40 PM. Reason: Comment about Photoshop.

  9. #9
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    Re: Converting Photo Negative to Positive

    From http://www.graphics-muse.org/artistsguide/?page_id=10:

    This question came up on the GIMP User mailing list and sparked an interesting thread. The summary: turning the scan of color negative film into color positive is a function of the scanner software and not a function of the GIMP (at least not at the moment). This is because all brands of film have different yellow and red masks that need to be removed. XSane can handle this for most film types, as can other scanner software.

  10. #10
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    Re: Converting Photo Negative to Positive

    Much of what I read claimed that XSane should be able to automatically convert the negative to positive by making the correct choices in the drop down boxes.

    I did do that and got the same (visually) result. Apparently the Epson Windows Scanner Software does it and XSane does not.

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