Engineering Commons^™

Estimating Scanning Characteristics From Corners In Bilevel Images, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

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. …

Scanner Parameter Estimation Using Bilevel Scans Of Star Charts, Elisa H. Barney Smith

Electrical and Computer Engineering Faculty Publications and Presentations

Scanning a high contrast image in bilevel mode results in image degradation. This is caused by two primary effects: blurring and thresholding. This paper expands on a method of estimating a joint distortion parameter, called the edge spread, from a star sector test chart in order to calculate the values of the point spread function width and binarization threshold. This theory is also described for variations in the source pattern which can represent degradations caused by repetition of the bilevel process as would be seen in printing then scanning, or in repeated photocopying. Estimation results are shown for the basic …