Abstract: A system for correcting the manufacturing errors and variations in the positional alignment and spacing of optical fibers in the scanning head of an automatic digitizing system. A scan head signature is produced by measuring the actual X and Y position for each optical fiber including the variation of each fiber from its nominal X and Y positions. An X correction circuit and a Y correction circuit use the head signature data stored in a signature correction memory to correct the X and Y positions of the stream of scan line data to thereby provide a true video scan of the document data.

Abstract: Computer graphics material after raster scanning and digitizing is examined for linear narrow width areas of like light value, typically black or white. Runs of like value on successive scan lines are compared for contiguity and, when found, are compactly coded by coordinates of first and last scan lines defining each area and thickness. Data compaction ratios up to 36 to 1, as compared to the amount of data required to store data for every picture element, can be achieved in real time.