Black And White Level Follower Device For An OCR System
Original Publication Date: 1979-Nov-01
Included in the Prior Art Database: 2005-Feb-20
In an optical character recognition (OCR) system the analog output from a photodiode must be digitized to give a binary (black-white) classification of a small area picture element (pel) on the scanned document. The proper threshold level for this analog signal is critical to producing an accurate sampled image of a scanned document. Any error in selecting the threshold level could cause distortion of the sampled image, complicating the character recognition process. Variations in the paper and the print reflectivity also complicate the process of the threshold level setting.