Television – Camera – system and detail – Combined image signal generator and general image signal...
Reexamination Certificate
1998-04-07
2003-02-18
Moe, Aung S. (Department: 2712)
Television
Camera, system and detail
Combined image signal generator and general image signal...
C348S243000
Reexamination Certificate
active
06522355
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to image sensing devices, and more particularly relates to correction circuits for image sensors.
BACKGROUND OF THE INVENTION
Dark current nonuniformities are present in CCD and CMOS active pixel sensors. The dark current nonuniformities result from material impurities which are not uniformly distributed in the substrate. Some prior art solutions to the nonuniformities include substituting neighboring pixels and smoothing the amplitude by analog signal processing methods. Analog signal processing results in art effects and incorrect pixel correction.
SUMMARY OF THE INVENTION
Generally, and in one form of the invention, the method of compensating for nonuniformities in an image sensor includes: providing an image sensing device; measuring test pixel signals from the image sensing device during a test mode; determining which test pixel signals are greater than a fixed threshold level; and calculating nonuniformity coefficients for the pixels having test pixel signals greater than the fixed threshold level. The processing for correcting pixel nonuniformities is in the digital domain.
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Austin Russell J.
Hynecek Jaroslav
Brady III Wade James
Moe Aung S.
Stewart Alan K.
Telecky , Jr. Frederick J.
Texas Instruments Incorporated
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