Thanks to a post on the DPReview Forums, I’ve got a link to an Open Source image editor for Mac OS X. According to their website, Seashore is substantially based on the GIMP, but clearly doesn’t include all of the GIMP’s features. What it does offer is very smooth user interaction, something the GIMP just doesn’t get.
Because it’s open source, built on Cocoa, and has a much more polished set of user interactions than the GIMP and other free image editing tools I’ve found, it might be a good place to start for the channel mixing project. Reading through their forums, I saw one mention of integrating Tiger ImageCore (sic) functionality in to Seashore, which I think is an idea that has merit. Core Image Funhouse is a great little app for applying effects layers to an image, but doesn’t have much in the way of a tools palette. Seashore has a nice, clean tools palette, but not much in the way of image effects.
I downloaded the latest source from CVS, and am planning to take a little time later today to get to know it.