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Converting RGB to CMYK correctly?

Posted: 2008-04-03T14:57:40-07:00
by agamemnus
Hello, can anyone tell me how to convert RGB to CMYK without varying color? I was able to do so manually in Photoshop, but I cannot do it in Imagemagick. I tried "-colorspace CMYK" with and without "+profile icm(/etc.)" and it is all the same: the converted image is lighter than the original.

Re: Converting RGB to CMYK correctly?

Posted: 2008-04-03T15:54:50-07:00
by fmw42
There have been a lot of posts related to this topic. Use the search feature and include the search words, RGB CMYK. To do it properly, you probably need to use a profile. But I am not an expert on this topic.

Also see:
http://www.imagemagick.org/Usage/channels/

Also certain image formats do not support CMYK. I think two are gif and png, but I that is from recall from another earlier message. So you should check on that.

Re: Converting RGB to CMYK correctly?

Posted: 2008-04-04T09:19:33-07:00
by brian_jackson

Re: Converting RGB to CMYK correctly?

Posted: 2008-04-04T13:10:21-07:00
by agamemnus
fmw42 wrote:There have been a lot of posts related to this topic. Use the search feature and include the search words, RGB CMYK. To do it properly, you probably need to use a profile. But I am not an expert on this topic.

Also see:
http://www.imagemagick.org/Usage/channels/

Also certain image formats do not support CMYK. I think two are gif and png, but I that is from recall from another earlier message. So you should check on that.
I did search, but none of the topics helped. I also tried "RGB to CMYK", but the search function just ignores "to".

The image is .JPG. JPG should work because Photoshop can do it just fine.

brian_jackson wrote:See this post: viewtopic.php?f=1&t=9227
Where can I get a color profile like the one Adobe Photoshop uses?

Re: Converting RGB to CMYK correctly?

Posted: 2008-04-22T10:12:47-07:00
by brian_jackson
agamemnus wrote:Where can I get a color profile like the one Adobe Photoshop uses?
I've got the AdobeICCProfiles-2.0-31 rpm installed which provides quite a few ICC profiles.

I don't use Photoshop, so I couldn't really help you there, but I'm pretty sure the profiles that Adobe provides are most likely the same ones they use in their own applications.

good luck