Defective pixels in a CMOS array give rise to spot noise that diminishes
the integrity of the resulting image. Because CMOS arrays and digital
logic can be fabricated on the same integrated circuit using the same
processing technology and relatively inexpensive and fast circuit can be
employed to digitally filter the pixel data stream and to identify pixels
having values that do not fall in the range defined by the immediately
neighboring pixels and the deviate from the neighboring pixels by more
than a threshold amount. Such conditions would indicate that the
deviation is caused by a defective pixel rather than by desired image
data. The threshold amount can be preprogrammed or can be provided by a
user or can be dynamically set using feedback indicating image quality.
The filter would also provide a solution for other sensors such as CCD,
although a single chip solution would likely not be possible.