[royboy] from the Arduino forum has recently made a post showing off his Arduino / PC ambient light system. The system is simple to wire up and easy to use, as long as your video is being sent from a PC, which for many of us that use “home theater pc” systems is very convenient. Using a sparkfun red/green/blue (non addressable) led strip, an ULN2003A, an Arduino, and a short sketch written for processing the project is easy to toss together and very effective too.
The processing sketch continuously takes screen captures and then takes the resulting pictures and averages all the colors together. That average color is fed down to the Arduino over its stock serial connection, where it is output to 3 of the pwm capable outputs. Those outputs are connected to the 2003 Darlington transistor array to switch the 12 volt led strip.
It may seem like it would be slow, as processing is an interpreted Java based language, plus serial communication, plus Arduino overhead, but its actually very responsive and completes its task with little or no lag. Join us after the break for a quick video to see for yourself.