Method of determining characteristic correction data for correcting output signal from image sensor

摘要

There is disclosed a method of determining characteristic correction data from reference data values picked up through an image sensor by scanning a reference original a plurality of times per one photoelectric conversion element of the image sensor. A running mean value of the reference data values is calculated with respect to a respective one of the photoelectric conversion elements, and is served as low spatial frequency component data. High spatial frequency component data is obtained by subtracting the running mean values from the reference data values with respect to the respective one of the photoelectric conversion elements. Noise components are eliminated from the high spatial frequency component data by averaging only those data values of the high spatial frequency component data which are not less than AV-Ksigma and not more than AV+Ksigma, wherein AV is a mean value and sigma is a standard deviation of the high spatial frequency component data, and K is a predetermined constant.