A method for encoding and decoding frames by generating a key bitstream such that the key bitstream never has to be stored is disclosed. The method consists of a key generation algorithm using a threshold matrix to generate a key that is very similar to original bitmap data. The key generation algorithm...http://www.google.es/patents/US7130423?utm_source=gb-gplus-sharePatente US7130423 - Threshold encoding of frame buffers
