US Patent 7092018 Image signal processor and deficient pixel detection method

A deficiency candidate detection circuit detects a deficient pixel candidate by comparing the image signal of a target pixel with the image signals of peripheral pixels, and address information of the deficient pixel candidate is stored in a position memory circuit. A deficiency determining circuit repeats the determination of a deficient pixel a number of times based on the address information stored in the position memory circuit, and determines address information of a deficient pixel from the continuity of the determination results. A deficiency registering circuit registers the determined address information in the position memory circuit. A deficiency correction circuit corrects the image signal of the deficient pixel according to the registered address information of the deficient pixel.