From BlenderWiki
You may have already reviewed this page where comparisons of different alpha matting algorithm results are compared (http://www.alphamatting.com/eval_25.php). It was the starting point for the Jan Reugll's foreground extraction tool for GIMP. Although his activity on this particular function has essentially stopped, it may be useful for you two to compare notes since he has spent time solving a similar problem.
One of the frustrations of open source is that it seems many people attack the same problem and get half-way there instead of combining forces to get something totally completed. This comment is not pointed at Blender (which constantly amazes me with the level of functionality and high quality), but just a pattern I observe in open source projects as a group. Effective green screen removal (or the larger subject of foreground extraction which is the generalized version of the same problem) is of importance to me. Although I lack the knowledge of C programming, Blender internals, or color manipulation, I'd be glad to assist in tracking down materials or even helping with doc (although my lack of specific technical knowledge on this subject may be a hindrance). Let me know.
Again, thanks for the effort you and others put into Blender (my ex sold Maya to LA studios way back when, when it was still Alias/Wavefront)- maybe you don't hear that enough from users.
Chuck
