About computer vision and interactive art :

http://www.flong.com/writings/texts/essay_cvad.html

The various computer vision plug-ins for Max/MSP/Jitter, such as David Rokeby's SoftVNS, Eric Singer's Cyclops, and Jean-Marc Pelletier's CV.Jit, can be used to trigger any Max processes or control any system parameters. Pelletier's toolkit, which is the most feature-rich of the three, is also the only which is freeware.
CV.Jit provides abstractions to assist users in tasks such as image segmentation, shape and gesture recognition, motion tracking, etc. as well as educational tools that outline the basics of computer vision techniques [Pelletier].