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Thread: Incorrect rendering of PNG in 2 bit color depth

  1. #1

    Default Incorrect rendering of PNG in 2 bit color depth

    I've found an error, which might be some kind of overflow/underflow condition, so I think it should be fixed.

    When opening a PNG file with 2 bits per pixel, there are a few pixels of wrong color at the and of the first line. In paletted pictures it's a color of palette index 0, in grayscale pictures it's black.

    This problem occurs in 64 bit version in Windows 10 as well as 32 bit version in Windows XP.

    I've attached an example file. The picture shows 4 red pixels in the top right corner when viewed in IrfanView. These pixels are not present in other programs. The file was created using PNGOUT.

    Testing version IrfanView 4.54
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	test2bpp.png 
Views:	34 
Size:	1.0 KB 
ID:	5983  

  2. #2
    IV Beginner
    Join Date
    Sep 2012
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    87
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    64-bit Win 7 Ultimate/Enterprise SP1
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    4
    IV 4.54 32-bit

  3. #3

    Default

    I've reported the error via email, waiting for the answer.

  4. #4

    Default

    OK. Irfan will try to fix that.

  5. #5

    Default

    I've received a test version, where the problem is fixed. This issue can be closed now.

  6. #6
    Moderator Enterprise User Bhikkhu Pesala's Avatar
    Join Date
    May 2007
    Location
    East London
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    6,548
    OS
    64-bit Win 10
    CPU Cores
    1

    Default

    Please attach the test version zip file in case others encounter the same problem.

  7. #7

  8. #8
    IV Amateur
    Join Date
    Sep 2020
    Location
    Hannover
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    11

    Default

    Thank you for sharing!

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