Estimating Scanning Characteristics from Corners in Bilevel Images

Degradations that occur during scanning can cause errors in Optical Character Recognition (OCR). Scans made in bilevel mode (no grey scale) from high contrast source patterns are the input to the estimation processes. Two scanner system parameters are estimated from bilevel scans using models of the scanning process and bilevel source patterns. The scanner's point spread function (PSF) width and the binarization threshold are estimated by using corner features in the scanned images.

These estimation algorithms were tested in simulation and with scanned test patterns. The resulting estimates are close in value to what is expected based on grey-level analysis. The results of estimation are used to produce synthetically scanned characters that in most cases bear a strong resemblance to the characters scanned on the scanner at the same settings as the test pattern used for estimation.