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Thread: Bug viewing PNG file

  1. #1

    Default Bug viewing PNG file

    First, irfanview (4.54 32bit on WinXP) cannot view the picture in forum's registration process:
    https://irfanview-forum.de/attachmen...034821&thumb=1
    It shows all black.

    Then, the two test image:
    https://www.w3.org/Graphics/PNG/all_seven.html
    gamma info is not processed.

    https://www.w3.org/Graphics/PNG/inline-alpha.html
    alpha info is not processed? Maybe it just used black as background, so I'm not sure if it is a bug or not, just bringing to your attention.

  2. #2
    Moderator Enterprise User Bhikkhu Pesala's Avatar
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    Default

    No issue with the forum registration image.
    Nor with the Alphatest.png

    Try changing the Window colour from black (the default) to something else in Settings, Viewing.

  3. #3
    Power User j7n's Avatar
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    Gamma correction is mostly irrelevant and superceded by color management, which can account for more differences in the transfer curve and primary colors. Usually a foreign monitor will produce more/less saturated colors and dynamic range. Gamma can only partially compensate for this. Files saved from IrfanView with the correction applied could never be fully restored due to lack of precision in 8-bit. The gamma in an image file could also be wrong because it was incorrectly detected or copied over from one file to another.

  4. #4

    Default

    Yes, changing "main window color" to white helps. Then only gamma header info bug remains.

  5. #5

    Default

    Quote Originally Posted by j7n View Post
    Gamma correction is mostly irrelevant and superceded by color management, which can account for more differences in the transfer curve and primary colors. Usually a foreign monitor will produce more/less saturated colors and dynamic range. Gamma can only partially compensate for this. Files saved from IrfanView with the correction applied could never be fully restored due to lack of precision in 8-bit. The gamma in an image file could also be wrong because it was incorrectly detected or copied over from one file to another.
    Gamma correction is a (simple) kind of color management method. That info could be wrong due to various reasons (one of which could be software pay no respect of it) , yet could be right. Supporting it is a good start.

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