GNOME Bugzilla – Bug 702044
Export in CMYK: Colors are wrong
Last modified: 2014-12-26 00:38:42 UTC
I can separate an image to obtain CMYK image (4 calques): that is good. BUT, when I use export in CMYK, then I obtain only 1 "calque" (in rvb). The 4 "calques" (in french) have disappeared in the file. When I try to open the image I have exported : only 1 "calque" is shown. I can't send this image to my print editor. I use Windows 8 on Dell machine.
Thank you for reporting this. I'm sorry to say that not everybody here understands French and a dictionary gave no matches. What exactly do you mean with 'calque' and 'rvb'? Which is the file format you export your image to? Are you using some particular plug-ins to separate and export your image or the built-in functions of GIMP?
Excuse me for my reporting but in fact I have perhaps found the answer. So, in first I use the CMYK plug-in of GIMP (functions : separate,export,dualtone,proof). So just a little french - a "calque" is a tracing or a traced design or a counter-drawing - a RVB is equal to RGB (G of Green becomes V de Vert) So I have some problems with my printer firm: some pictures are very black and they said to me that they can't open my files. They always say "we can't open" or "they are not in CMYK". So I have verified the files : they were made with GIMP CMYK. I was sure. I have opened the files "export with GIMP in CMYK" and surprise : the four tracings disappeared. So I have thought there was a bug in GIMP. So I have written to you. In evening, I have installed Photoshop. I made the same things and I obtained the same result. So , sorry, I have been too fast to report "a bug". In fact I suppose that all softwares do the same thing: 4 tracings out and after 1 tracing in. The other problems are perhaps : problems of compatibility in Windows (XP or 8 for example) or some problems of transmission. More, curiously with GIMP I have some problems with blue. finally : 1) I have remarked that CMYK with GIMP are darker than with photoshop (it's in fact 2 different formulas on black) 2) It's not a bug in GIMP : other softwares do the same thing.* So I make my apologies. I consider this problem as resolved. Thanks.
It's perhaps a good idea to install the 2 versions of algorithm CMYK in GIMP : GIMP would the sole to offer this possibility. Perhaps the modification in informatic code are light (only the function that calculate colours ?) Photoshop don't do it. We could choose the best manner to make CMYK (clear or dark, good blue in one and bad with another or good green with one and bad with other...). Thanks
To me the remain of the original bug seems to be either a duplicate of bug #78265 or bug #481264 (see comment #2 there). Does anybody of the better people knowing CMYK better than me confirm this? Did you also convert to the right color profile (see Image/Mode/Convert to color profile), set the proper Rendering Intent and check the 'Black point Compensation' setting there? Setting OS=all, as this is not only Windows specific.
Closing this bug report as no further information has been provided. Please feel free to reopen this bug if you can provide the information asked for. Thanks!