1. In a system for line-wise compressing and decompressing a picture field which is made of a plurality of rows and columns of pixel data, a compression device comprising: a first input for receiving said picture field pixel data; a read/write memory organized on a word basis connected to store at least a line of said pixel data received from said first input; a first shift register coupled to receive a row of said pixel data from said first input; a second shift register connected to receive pixel data from said read/write memory which, during a memory cycle with said first register, receives the preceding row of pixel data having the same column position as said first register data; a compression translator connected to said first and second shift registers, said compression translator generating from line pixels received from said first and second shift registers a series of compression bits, successive lines of pixel data generating successive groups of compression bits which have neither fill bits nor end of line bits; and, a series to parallel converting buffer fed through a first input by said compression translator, and buffer having a dynamic second input and output for communicating with a parallel local communication bus.
5. A system as claimed in claim 1 wherein each successive group of compression data indicates a transistion between a black pixel and an adjacent white pixel in a line of pixel data.