Hm. Interesting problem, as -- well, let's call them "c-beasts" -- come in variety of colors laid in various patterns, effectively wearing disruptive camouflage. One application of image recognition to such beasts I am aware of was based on shape -- instead of normal image, a shadow was analysed (http://www.quantumpicture.com/Flo_Co...lo_control.htm) -- and the shapes are quite similar across the population. Of course, there's famous Google c-recognition algorithm, but I bet the big G has some more power -- both raw computational and engineering -- that our small community.

On the other hand, let's consider goals, not means... If you are simply trying to keep your yard c-free, I heard that application of tiger dung in the perimeter works wonders. Try to obtain some and please report back the results

And the real challenge, I think, would be dog recognition, including not only established breeds, but mutts as well.