[Digikam-devel] [Bug 128377] New: Adjust levels: histograms don't match, bad "auto level" function

[Matthias Wieser]

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http://bugs.kde.org/show_bug.cgi?id=128377         
           Summary: Adjust levels: histograms don't match,  bad "auto level"
                    function
           Product: digikamimageplugins
           Version: unspecified
          Platform: unspecified
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: normal
          Priority: NOR
         Component: AdjustLevels
        AssignedTo: digikam-devel kde org
        ReportedBy: mwieser gmx de


Version:           unknown (using KDE 3.5.2 Level "a" , SUSE 10.0 UNSUPPORTED)
Compiler:          Target: i586-suse-linux
OS:                Linux (i686) release 2.6.13-15.10-default

I'm using today's svn version.

Opening the "adjust levels" digikamimageplugin shows two histograms. But even without doing any modification the "original image"-histogram looks different to the "target image"-histogram.

Second problem:
Pressing the "auto"(?) button changes the colors (color temperature) of the image. That's bad.
The reason is that it changes the color channels individually instead of only adjusting the luminance channel.

Example: take an *underexposed* picture of a green leaf. Press "auto" to stretch the contrast. Result: a grey leaf :-(