Using a CMYK PSD without Photoshop

Question

I have run into a common, yet difficult problem. I do not use Photoshop for image manipulation. Since all my work is web-based, GIMP does what I need in 99% of the situations. The problem is that I occasionally receive PSD files with CMYK encoding rather than RGB encoding. These files will not open in GIMP, nor will they convert in ImageMagick.

Has anyone found a good solution for converting CMYK files to RGB files (either PSD format or a flat format like PNG) that does not involve the use of Photoshop? Say a plug-in for GIMP or a standalone utility?

Solution 1

Assuming you have access to a Windows computer, freewares like IrfanView or XnView can open it and resave in whatever format you need too. XnView knows more formats, and has a NConvert command line version for this task, but IrfanView can do command line operations as well - I usually install both, preferring IrfanView's interface.

Solution 2

I just had luck with Imagemagick:

convert input.psd -colorspace rgb output.png

It created a bunch of files named output-[0-9].png one for each layer. Good enough to start working with it on Gimp. When I tried to open those PSDs in Gimp 2.6 the message I got was:

Error loading PSD file: Unsupported color mode: CMYK

I'm using Ubuntu Lucid's Imagemagick:

Version: ImageMagick 6.5.7-8 2009-11-26 Q16 http://www.imagemagick.org
Copyright: Copyright (C) 1999-2009 ImageMagick Studio LLC
Features: OpenMP

Solution 3

There is a very similar question on Superuser.com where one answer lead me the Program Krita. I've opened a CMYK .psd file of about 26 Mb in Size (6761 x 2423 pixels) in Krita version 2.8.1 with KDE version 4.13.3 in Ubuntu Linux 14.04. After converting the color space from CMYK to RGB using the dialogue Image-->Properties in Krita this program is able to store the image as a RGB PNG file. Update: Nicolas pointed out in a comment below: if your .psd file contains several layers it might be necessary, to go into Image-->Convert Image Color Space before saving.

Afterwards I was able to open the resulting RGB PNG with gimp and all colours were converted in a reasonable way as far as I can tell.

Krita was already mentioned in a comment (by Heiken) above. But since Krita is in my opinion one of the best suitable answers to the original question I decided to post this answer to report about my experience here.

Solution 4

Also you can import it to Scribus, if use 1.3.5 or higher in Scribus you can change the layer visibility and blend mode, the image can be saved in tif, jpg, png, pdf, ps/eps; after, any of this can be edited with Gimp.

Solution 5

Seems like a plugin exists here http://cue.yellowmagic.info/softwares/separate-plus/index.html which includes:

separate RGB to CMYK conversion / Softproofing plug-in (improved version of Alastair M. Robinson's "Separate" plug-in

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