Carolyn A Harris

US Patent:

20020122213, Sep 5, 2002

Filed:

Mar 1, 2001

Appl. No.:

09/797268

Inventors:

Edward Hill - Carditt CA, US
Craig Johnson - San Diego CA, US
Carolyn Harris - Escondido CA, US
William Amidei - Carlsbad CA, US

International Classification:

H04N001/04

US Classification:

358/474000

Abstract:

A circuit connected to a linear array of photosensors generates image data representative of information printed on a document and adjusts the gains applied to the outputs of selected ones of the photosensors to eliminate streaks in the image data otherwise due to the selected photosensors imaging debris on the optical reference surface. The circuit determines which photosensors have low output values during a factory scan of a clean white reference surface. During a subsequent user environment calibration scan, low output values are adjusted to the average of their neighbors, but only for locations not identified as having low outputs during the factory scan. The circuit additionally performs a PRNU compensation and further adjusts the gains applied to each of the outputs of the photosensors so that all of their output values have a substantially uniform value.