[Bug] Perceptual Gradients change from CMYK to a RGB conversion of CMYK?
When I create a white to black gradient in CMYK mode as classic and it looks fine when separations previewed. When I change to peceptual it adds color in the areas from about 1% to 99% and does not stay black only. I tried it with 100% cyan to white and it added magenta and yellow in the same areas.
Jon
shared this idea
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Sergey Osokin
commented
Mathematically, a gradient is generated by calculating each point based on the left and right colors and the location of that point. The computations are performed by color channels, so parasitic hues appear in the final color of a point. The perceptual gradients in Photoshop and Illustrator use the OKLAB space, which has issues with a parasitic magenta hue in the case of interpolation between white and blue. And here it affects that the transformations between CMYK and OKLAB do not go directly, but probably through RGB, which has a greater effect on the appearance of extra channels in CMYK. The paid GradientBlender script will have the same problem with blue in OKLAB mode. This is a common algorithm problem
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Perceptual gradients are calculated using Oklab color space:
https://en.wikipedia.org/wiki/Oklab_color_space
So yes, it gets converted into CMYK, using the working color space. It cares more about transitions than respecting the actual colors of the stops also.
If you wish to keep these and have more control about the intermediate colors, perhaps you’d better seek an alternative solution, like this script: https://www.youtube.com/watch?v=Q3FG0g5yDm8 -
Jon
commented
See the screenshot of the issue below.
