Over time, CCD imagers will begin to show blemishes. A blemish is a pixel showing a significantly higher or lower value compared to the average pixel value of all the pixels (see Fig.1). In various applications such a blemish can be mistaken for a surface artifact, contamination or glare, requiring additional image processing to remove this effect.
The blemish compensation method used in some JAI cameras is based on a nearest neighbor interpolation and works for monochrome and colour sensors (see Fig.2). Since the blemish compensation only concerns pixel positions, it is independent of all subsequent gain and shutter settings. The function compensates up to 256 pixel values and is easy to use with the simple built-in calibration procedure.