Description: takes one or two strips as input
Description: key away a given color (make it black and transparent or replace 
Description: it by another image) setting the tolerance to 0 only makes 
Description: pixels, which exactly match the given values for R, G and B, 
Description: transparent.  setting it to 255 makes all pixels transparent.

Author: Stefan Gartner 
Email: Stefan.Gartner@fhs-hagenberg.ac.at 
Website: http://orpheus.fhs-hagenberg.ac.at/students/mtd/mtd97047/
License: BSD