Image enhancement for optical character readers

摘要

A system is shown for enhancing signals produced by the scanning components of an optical character reader. Analog video signals produced by a scanner are converted to digital video signals representing a plurality of pixels. Digital video signals representing a matrix of pixels where the matrix is smaller than the individual characters are summed together to provide a reference base of brightness. A digital video signal located at the center of the matrix of interest is scaled to a value corresponding to the number of pixels in the matrix times its brightness level. The scaled center signal is then compared with the summed signals. The scaled center signal is made to read "white" if it is brighter than the summed signals and made to read "black" if it is darker than the summed signals.