Re: [Gimp-user] Histogramm -- values

Elle Stone and Nicolas Robidoux, can you please also have a
look on this topic? Thank you in advance.

Wow, this was a very elaborate answer ...

Fred Weinhaus also answered me and he is pointing to some transfer functions that ImageMagick uses, see

He also gives some helpful illustrations what effects different transfer functions have on the image:

I understand what Elle says in regard to histogram clipping, i.e. max(R, G, B) being very helpful for finding the white point -- while min (R, G, B) in regard to the black point is missing.

Perhaps one should give the user just a few more options what to display in the histogram and how to transfer R, G, B into a single 'value'. I would be very lucky with 'Rec709Luma' as defined by ImageMagick. I understand that GIMP internally uses the sRGB colour space at the moment (?).

A standalone feature for GIMP would be the possibility to display a cumulated histogram, which would for instance demonstrate the effect of equalisation better than an ordinary histogram. This should be easy to implement, I guess, and would be a simple check box for the user.

BTW: Besides equalisation, one could also try to meet other cumulative histogram distribution, like a Gaussian bell curve, see

Wolfgang Hugemann

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