CALIBRATION MECHANISM FOR A CVT IMAGE INPUT MODULE
Original Publication Date: 1983-Jun-30
Included in the Prior Art Database: 2004-Apr-04
Xerox Disclosure Journal
In image input scanners, to assure continued image quality, periodic shading correction is used to compensate for the individual variations across the video raster. Shading correction is necessary due principally to the high and low frequency non-uniformity of the scanning array (such as, for example, a Charge Coupled Device or CCD) and to variations and the less than ideal performance of the scanner optical and illumination systems. Essentially, shading correction is accomplished by calibrating or adjusting the image signal or pixel output of the scanning array in accordance with a "correct" image output signal derived from a reference or calibration image. For this purpose, the calibration image is imaged periodically by a calibration/correction procedure.