Sorry I assumed high DR images or plenty exposure pushing because with low DR the tone mapping should basically be a no op with any visible difference coming from the tone curve part of sigmoid/filmic so basically just a base curve?
No I just set the background to as close to black as I can and set the channel colors to be brighterâŠthis you can do with css⊠the alpha to brighten the whole thing has to be changed and then compiled⊠you can find the lines that control the various things related to the histogram in darktable.css
Hi!
I just want to share some observations, I think it would be a good idea restoring the luminance after the rgb tonemapping.
The issue is that rgb per channel tonemapping becomes a little destructive when the saturation increase.
An example:
This is an image tonemapped with rgb tonemmaping
If we desaturate the already tonemapped image we obtain this
If we desaturate the original hdr image and we do the tonemapping after, we could get a more detailed image
Now the idea is to remove the luminance from the rgb tonemapped image and add the luminance tonemapped image
(Note that this particular image has issues with out of gamut colors)
A simple way in pseudo code to obtain this without actually decomposing the image is :
i=Original_image
Lum= get luminance from i
tm_lum=tonemapping lum
tm=tonemapping i (with or without hue preservation)
Lum2= get luminance from tm
tm_luminance_restored=tm/lum2*tm_lum
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Interesting idea, some questions.
Has anyone else done this that you can link to?
Is the bottom image processed exactly as described?
What to do with colors that get pushed out of display gamut?
We will have the same problem as rgb ratio with no gamut mapping even though there will be a desaturation of bright pixels. Have a feeling that f ex skies will look desaturated even after this operation.
I donât think
Yep
Good question, ideally I think that extreme saturation should be fixed before tonemapping with something like a proper dual illuminant profile
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Let the display transform deal with them.
After more testing with very OOG flowers this could produce little color banding artifacts, I see this problem only with flowers photography.
Using CIE lab or the simple ycbcr color spaces solves the problem.
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