GNOME Bugzilla – Bug 586521
CMYK Color Selector / CMYK Color Mistake
Last modified: 2015-07-25 17:05:04 UTC
Please describe the problem: The CMYK Color Selector is working incorrectly. But it seems, that the error is not in the color selector itself, i guess it's in the GIMP Core, because if I want to import EPS-Files, i get the same wrong colors. Steps to reproduce: For example i wanted to select the following color in CMYK Format with the color selector: 32 86 9 1 In real it's a darker pink, but in GIMP it's already a kind of purple. Of course i checked the order of the colors... To see correct colors, you may use the color selector of Scribus.net. When i imported an EPS file with the same pink background, it's also converted in this wrong violett. The error is not in GhostScript - because scribus also uses GhostScript and doesnt have this problem... and of course, if i just use the color selector.... Actual results: I get the wrong color Expected results: Does this happen every time? Yes Other information:
Did you specify a CMYK profile in the Color Management preferences? The conversion between RGB and CMYK is totally undefined without a profile. Most likely you simply did not specify a profile and thus the naive conversion is used.
No, i didn't. I thought there is a common CMYK standard which is usually used in every application, when you don't create your own profile (because in Scribus it worked without changing anything - i got the EPS from a customer). Bad shot? Now i feel like a layman... o0 Are you going to use he same standard CMYK profile like Scribusin future?
They probably read the profile in the EPS, GIMP doesn't
What info are we waiting for?
This bug is invalid, imo. The only way to get "darker pink" using that combination of CMYK values is using uncorrected CMYK primaries straight from RGB (i.e.: magenta = 100%R+100%B). That's not suitable at all for print and therefor it can't be how it looks in reality, since CMYK inks can't have that kind of saturation. GIMP result should be considered correct, since it uses a profile to simulate how that substractive mix would look on paper. Also notice that Scribus color selector will show the same color than GIMP when color management is used.
That might be a bug to reevaluate against the changes in 2.9.
See comment 5, GIMP is doing the right thing here.