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?

Answer 1

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 

Answer 2

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.