METHOD FOR DETECTING BLEMISHES NEAR THE PERIMETER OF A CCD IMAGE

In a method of detecting blemishes in the proximity of the perimeter of a CCD image, pairs of adjacent pixels in the proximity of the perimeter are sequentially considered. For each pair of adjacent pixels, a plurality of pixels, in a blemish detection pixel pattern extending toward the center of the image are considered. The sum of the four outer pixels in the pixel pattern are compared to the sum of the inner pixels and the variance is compared to selected minimum and maximum differences. When the variance is outside either the minimum or the maximum differences a blemish has been detected. When the difference is within the two differences no blemish has been found. The blemish pattern is moved one pixel toward the center of the image and the process repeated. The difference comparison is repeated for a selected plurality of times and if desired the differences can be changed for some of the comparisons.