I was going to develop it further by first creating a greyscale version of the image. This would (I think) help to identify areas of similar colour because there are only 256 greys (even in 32bit images). Then, I was going to use this greyscale image to perform the fill search on the real image.
Still not convinced it would have worked any better, but I didn't have time to try it, anyway. :)
Still not convinced it would have worked any better, but I didn't have time to try it, anyway. :)