So whats going on. basically we've set the arduino up to respond to a particular message. this message consists of a header (the letter "C") a dud byte (some strange serial problems caused this to be implemented) and the bytes of data (R G B respectively)
All processing is doing is generating these messages based on a pixel in an image, when we click the mose location is recorded and the message is built and sent to the audrino over a serial connection.
See the attached files for the software for this project, hitting run in processing should bring up a screen like the one below, although it will depend on what image you choose to load.
ColourMap goes in processing
RGB_LED_arduino_code goes in (you guessed it) arduino.
Make sure you load this onto the arduino before you run the processing file or it wont do anything.
if you having trouble check the following:
Is the arduino plugged in
is the arduino power light on
have you wired the led correctly
have you chosen the correct serial port in processing
if your still having trouble post a comment below and I'll do my best to answer it.