[Digikam-devel] [Bug 144155] wrong(?) histogram y-axis when blown-out over/underexposure

[lparrab at gmx.net]

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http://bugs.kde.org/show_bug.cgi?id=144155         




------- Additional Comments From lparrab gmx net  2007-04-13 03:47 -------
yes, the logarithmic histogram does work perfectly: the calculation and the curve are "correct"...

however, I think that logarithmic scale is great for some physics or math graphs.. but in photography, a logarithmic histogram does not tell (at least not to me, specially not at the first blick) the proportion of the color distribution in the image

Since the problem is normally on the extrem left or right of the histogram, you could simply cut off the 1% of either side (not really cut, but don't take into account for the Y-axis)

Other approach would be to use a given percentil to set the limit. 
I'm attaching an example-patch to the current SVN version (anonsvs) which ensures that 90% of the pixels take at least some 33% of the Y-scale.

The 90% and 33% are arbitrary values and you could play a bit with them, but they seem to give a nice result.
I'm also attaching a screenshot of digikam with(svn) and without the patch(0.9)

regards. Luis