Is there a way to prevent out of gamut colors from appearing in the color picker?
I’m wondering if this might be of use:
I’ve already tested all kinds of color pickers, and I’ve enabled “the color picker uses a different color space than the image.” But the blacks and saturated colors outside the color gamut space keep appearing in the picker.
What is your color space? 
I always use the default and this problem does not show up for me.
I use the image with Adobe RGB (1998), and the color proof in CMYK Gracol2006_Coated1v2.icc.
Make sure to use blackpoint compensation with the softproofing, and also for the final conversion to CMYK. The color selectors always use blackpoint compensation.
Beyond that, try to accept colors are sometimes out of gamut. The thing you don’t want to be out of gamut are your most important contrasts (so if one color in a contrast is out of gamut, that is fine, but it becomes a problem if both colors participating in a contrast are out of gamut, because then it might get lost).
Black point compensation is enabled. My problem is that I have many colors in the color picker that are outside the color profile.
You have three options:
- Use the specific color selector, and only use the cmyk color profile you’re proofing against.
- Use the wide gamut color selector and set the custom color space in the settings to the proofing color profile.
- Use the advanced color selector and set the custom color space in the settings to the proofing color profile.
Now, you will still have out-of-gamut warnings when selecting colors at the edge of the gamut. This is because of rounding errors when converting those colors to the image colorspace (adobe rgb in this case). This is inevitable with CMYK profiles, because they are LUT based. However, if you turn off the out-gamut-warnings, you will see that the colors are virtually the same (because they are).
The most important thing is that the important contrasts aren’t out of gamut, and the out-of-gamut-warnings are meant to be a guide to figure out whether the important contrasts are out of gamut. Nothing will break if a color by itself is out of gamut.
The solution I came up with was to create a color palette using the profile that will be printed. It only includes the basic colors: black, white, cyan, yellow, green, 100% M 100% C blue, and 100% C 100% Y green. When I can’t find a color in the color picker within my profile, I create it by mixing these basic colors. Mixing these colors doesn’t affect the print profile.