Abstract: The output (18) from an optical sensor is recharged for a time dictated by the output of the digital-to-analog converter (11). A previous count indicative of the recharge time is stored in memory (52) which controls the converter (11). This count is manipulated in incrementing circuit elements (54) (70 and 72) depending on the time the comparator (12) signals a difference signal, indicative of a period of recharge.

Abstract: A pattern recognition system in which the visual image of the scanned character or pattern is placed within a defined area, referred to as a video space, which contains ideally only picture elements associated with the character to be recognized. Initial alignment of the visual image in the video space is made by one of several prior art techniques (e.g., mark on the form). The pattern of picture elements in this video space are analyzed to determine what the visual image represents and the coded representation of this character is transmitted to associated equipment which includes apparatus for specifying the ideal coordinates or position of the recognized visual image in the video space. To aid in alignment of subsequent visual images in the video space, selected alignment features of the analyzed visual image are computed and these selected features are compared with ideal feature alignment values for the particular character being recognized.