[Digikam-devel] [Bug 139681] New: function for semi-automatic whitebalance

[Alexander Neundorf]

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http://bugs.kde.org/show_bug.cgi?id=139681         
           Summary: function for semi-automatic whitebalance
           Product: digikam
           Version: 0.8.2
          Platform: Ubuntu Packages
        OS/Version: Linux
            Status: NEW
          Severity: normal
          Priority: NOR
         Component: general
        AssignedTo: digikam-devel kde org
        ReportedBy: neundorf kde org


Version:           0.8.2 (using KDE KDE 3.5.5)
Installed from:    Ubuntu Packages
Compiler:          gcc 4.1.2 
OS:                Linux

Hi,

until now I didn't find a function for semi-automatic whitebalance correction neither in digikam, krita nor gimp.
Depending on the lightning conditions, different whitebalance correction factors have to be applied to the red/green/blue channels.
Digital cameras don't always get it right.
Digikam (or a plugin) should have a function to fix this:
-ask the user to select a small white/neutral grey area in the image, e.g. click somewhere and then use the average of a 3x3 area around that point
-make sure that the color channel values in this area are somewhere between maybe 5 and 95 percent (otherwise you can get errors if the colors are to dark or overexposed)
-use these pixel values to calculate the color channel correction factors so that the pixels in the selected areas become white/neutral grey: take the biggest color channel and calculate the factors for the other two channels so that they get the same value
result: a really good whitebalanced image :-)

Alex