exposure linear vs nonlinear

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exposure linear vs nonlinear

Darky

I am a little bit confused about the impact of exposure on sRGB values of images.
I expect a linear influence on the intensity and a nonlinear impact on sRGB values.
But darktable behaves different!

Take for example a PNG file with white value sRGB = 255.
If you lower the exposure with -1 EV, the intensity is reduced from 100 % to 50 %.
This has to result in the reduced value sRGB = 188 and not 128!

To my humble understanding the current exposure calculation of darktable 4.01 is not correct.
Thank you for confirmation, comments …

priort

I responded on pixls.... I think its the module order setting...needs to move exposure module postion...then things appear good to me....

Darky

Thank you Todd. I was not sure about the best location/forum for this topic/bug.
Pixls seems to be more convenient for rich editing with images.
If somone else is interested, here is the URL: sRGB calculation of color picker wrong

Darky

In fact the reason was, that DT is not switching with JPG or PNG images to the correct module order "v3.0 for JPG/non-RAW input". With this mode the influence of exposure module is ok.

However the DT color picker has some severe limitations as described in the pixls discussion of my previous post.