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

[Gerhard Kulzer]

Am Friday 13 April 2007 schrieb lparrab at gmx.net:
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> http://bugs.kde.org/show_bug.cgi?id=144155
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> ------- 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

I think the contrary is true, in photography you __always__ use logarithmic 
representation because it corresponds more to the subjective impression 
called "Lightness". The actual subjective law is a 1/3 power law 
(http://www.poynton.com/notes/colour_and_gamma/GammaFAQ.html#lightness). 

So if we want to improve the histogram I think the best would be (because it 
corresponds to our visual perception) to represent the histogram as a power 
law, and neither log nor linear, cupped or otherwise.

My 2ç

Gerhard



-- 
Hakuna matata
http://www.gerhard.fr
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