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?
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.