Windows11 (23H2), display resolution 3840x2160, win scaling 150%
Instruments - mono mixer
see instrument effect intensity at min/max in GIMP (☑ Preserve luminosity) and Photoshop test imagehttps://docs.gimp.org/2.10/en/gimp-filter-mono-mixer.html wrote: Preserve luminosity
The mixing can result in an image where some of the colors are too light. This option lessens the luminosity of the color channels while keeping a good visual ratio between them. So, you can change the relative weight of the colors without changing the overall luminosity.
Here is how the Preserve Luminosity works in the monochrome mode: “For example, suppose the sliders were Red:75%, Green:75%, Blue:0%. With Preserve Luminosity disabled, the resulting picture would be at 75%+75%+0% =150%, very bright indeed. A pixel with a value of, say, R,G,B=127,100,80 would map to 127*0.75+100*0.75+80*0=170 for each channel. With Preserve Luminosity enabled, the sliders will be scaled so they always add up to 100%. In this example, that scale value is 1/(75%+75%+0%) or 0.667. So the pixel values would be about 113. The Preserve Luminosity option just assures that the scale values from the sliders always adds up to 100%. Of course, strange things happen when any of the sliders have large negative values.” (from the plug-in author himself).
Suggestion
- add Preserve luminosity
effect should be applied to RGB colors and Colorize Saturation
Not sure if dedicated setting is required, maybe just update the calculations to match Photoshop
- set default values to something usable, eg
- RGB to 33%
- Saturation to 20% (like in Photoshop)
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