Pixy CMU Cam5 by Pixycam.com is a fast vision sensor for DIY robotics and similar applications. You can teach Pixy an object just by pressing a button. Use Pixy for lots of different applications!  It’s capable of tracking hundreds of objects simultaneously and only provides the data you are interested in.

Pixy comes with a cable to plug in to Arduino, so you can quickly get started. No Arduino? No problem! Pixy has a multitude of ways to talk to other devices.

Pixycam.com offers free software libraries for Arduino, Raspberry Pi and BeagleBone Black. Pixy also makes your life easier by only sending the data you’re looking for.

Want to dig deeper? Pixy is entirely open-source (hardware, firmware and software). Pixycam.com offers a helpful wiki, and you can always ask a question on their forums.