Data logging light sensor readings on port 3 reads the percent of light reflected back from red, blue, white, and black.
The two high readings are white and red. The two low readings are black and blue.
Webpages and pictures on http://www.marshall.edu/LEGO Web camera on http://legocamera.marshall.edu NASA site of Remote Sensing on http://SENSORSCITY.marshall.edu Teleoperate LEGO CITY at http://lego.marshall.edu