Abstract: A technique and apparatus for facsimile encoding wherein patterns isolated in each incoming image or picture are compared against stored library patterns, and an identification number associated with a matching pattern and its location in the facsimile are encoded in place of a pixel-by-pixel pattern description. The library of stored patterns used for matching purposes is organized such that frequently occurring patterns are examined early in the matching process, decreasing processing time. Identification numbers associated with matched patterns on each scanning line are numerically sorted, so that the ID's can be differentially encoded. At any time during pattern matching, detection of significant differences between the incoming pattern and a particular library pattern generates a reject decision, immediately terminating that match attempt.

Abstract: A method and apparatus for the transmission of two-tone pictures progressively in several stages. Progressive transmission enables a viewer to receive and utilize pictures in a small fraction of the normal transmission time. In a first stage, information representing groups of picture elements of preselected lines of the scanned picture is transmitted which allows a coarse version of the picture to be reproduced at a receiver. During the subsequent stages the horizontal resolution of the previously transmitted scan lines is improved and additional scan lines are transmitted in a specific order until the received picture is an identical copy of the original picture. The progressive picture information is efficiently transmitted in one of several line-by-line codes resulting in a total transmission time not significantly longer than the time for a nonprogressive transmission.