Patent US 5,164,819

A data compression system for reducing the bit rate for transmission of a color television signal to a value that telephone lines and hard wired systems can accommodate employs a two-color plus color bit map block coding scheme which enables a plurality of subsequent compression techniques to be employed in a single system. The two-color block coding inherently compresses the data which is then further compressed by a combination of intra-frame and inter-frame comparisons and compressions and bit map encoding and compressing as well as tolerance based decision compression techniques for reducing the number of bits needed to represent the color changes.