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  1. Qt
  2. QTBUG-132875

CMYK to RGB conversion on big endian produces significantly wrong colors

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    • Icon: Bug Bug
    • Resolution: Fixed
    • Icon: P4: Low P4: Low
    • 6.8.2, 6.9.0 Beta2, 6.10.0 FF
    • 6.8.1
    • Image formats
    • None
    • Linux/X11
    • 7ad2083ec (dev), 4d34eee36 (6.9), 4a451597f (6.8)

      Conversion from TIF (CMYK) to BMP (RGB) produces different output depending on architecture.

      Source file:

      cmyk8.tif

      This is result (looks OK) on amd64:

      However, on PowerPC, the colors are significantly different.

       

      I suspect that QImage::convertToFormat doing wrong conversion.

      I use following simple program to reproduce the problem with conversion from TIF->BMP:

      https://invent.kde.org/frameworks/kimageformats/-/blob/master/tests/imageconverter.cpp

      ./bin/imageconverter cmyk8.tif output.bmp

        1. cmyk8_converted_amd64.bmp
          27 kB
          Daniel Novomesky
        2. cmyk8_convertedBE.bmp
          27 kB
          Daniel Novomesky
        3. cmyk8.tif
          128 kB
          Daniel Novomesky
        4. cmykprint.cpp
          2 kB
          Daniel Novomesky
        5. mm_cmyk8.tif
          191 kB
          Mirco Miranda
        For Gerrit Dashboard: QTBUG-132875
        # Subject Branch Project Status CR V
        617898,2 Fix CMYK8888 on big-endian platforms dev qt/qtbase Status: MERGED +2 0
        618081,2 Fix CMYK8888 on big-endian platforms 6.9 qt/qtbase Status: MERGED +2 0
        618123,2 Fix CMYK8888 on big-endian platforms 6.8 qt/qtbase Status: MERGED +2 0

            peppe Giuseppe D'Angelo
            novomeskyd Daniel Novomesky
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              Created:
              Updated:
              Resolved:

                There are no open Gerrit changes