Abstract: To encode data representative of correlated images, a sequence of arrays of source image data is provided in which each array is representative of an image. Each array of source image data is partitioned into a plurality of source image-data blocks. For each sequence of source image-data blocks, at least one prototypical image-data block is derived from at least a portion of the source image data of the sequence. For each source image-data block, a translation coefficient and a number of scaling coefficients equal to the number of prototypical image-data blocks associated with the sequence are determined. A difference image-data block is formed for each source image-data block from elements of the source image-data block minus the associated translation coefficient minus the sum in turn of each associated scaling coefficient multiplied by elements of the corresponding prototypical image-data block.

Abstract: Communications between a Host Computing System and a number of remote terminals is enhanced by a data compression method which modifies the data compression method of Lempel and Ziv by addition of new character and new string extensions to improve the compression ratio, and deletion of a least recently used routine to limit the encoding tables to a fixed size to significantly improve data transmission efficiency.