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RGB adjustements highly non-linear

Posted: Mon Nov 10, 2025 2:40 am
by oayz
May not be a bug but a feature :-) In RGB ajustements:

0-50 basically make no effect, somewhere around 70 it starts to actually adjust color, around 100 become visible:

Here is the example:

R, R_agjust, new_R:

64, 0-50, 64 (no change !!!)
64, 0-60, 65
64, 70-80, 66
64, 100, 67
64, 120, 70
64, 140, 75
64, 160, 79
64, 180, 86
64, 200, 94
64, 220, 104

Adjustment curve is highly non-linear and not as expected. Normally we either increase RGB by %% ( +/-100%) or by value (+/- 255)

BTW, I believe it's a regression for quite a few releases

Re: RGB adjustements highly non-linear

Posted: Wed Nov 12, 2025 5:14 am
by user0
it has been changed in 181

yep, some adjustments are welcome
  • calculation
    - revert calc to the one from 180 for RGB sliders in Enhance colors
    Color balance in Batch convert works as expected
  • scale's UOM
    - maybe change scales to % (w/o % indicator) for Brightness/Contrast, RGB, Hue, eg like in Affinity/Ps
    Percentage scale seems more intuitive and I just don't see advantages of using an integer scale (255 and 127 (255/2)).

    Example
    instrument_ranges.png
    instrument_ranges.png (32.11 KiB) Viewed 75 times

Re: RGB adjustements highly non-linear

Posted: Wed Nov 12, 2025 8:43 am
by xnview
:bugconfirmed: Thanks to your detailed description I can reproduce the problem.