CCD or CMOS CHips are light sensitive 

They convert light to electrical current 

The pixels on the sensor chip convert light to an electrical charge and the brighter the light the higher the charge; less light=less charge 

In CMOS single chip cameras (the kind we are using in class) each of the pixels on the chip has a little color filter, either red, green, or blue 

A color video image is made from all of the different combinations of red, green, and blue  -- Bill Brown