An optical reader system includes a plurality of sensor elements for providing a picture signal. Before initiating an actual reading operation, a white background plate is scanned to obtain reference information. The white background plate data is reversed to obtain a reciprocal of the white level and...http://www.google.es/patents/US4383275?utm_source=gb-gplus-sharePatente US4383275 - Read-out level compensation in an optical reader system
Read-out level compensation in an optical reader system
