Patent ID: 7359090

Claim:
A method for shading one of a plurality of optical sensing elements of a scan bar of an optical scanner having a shading calibration strip including a white area and a black area comprising the steps of: a) obtaining white and black reference values of the output signal of each of the plurality of optical sensing elements while relatively moving the scan bar over the white and black areas of the shading calibration strip; b) calculating an average white value of the white reference values for each of the plurality of optical sensing elements; c) calculating an average black value of the black reference values for each of the plurality of optical sensing elements; d) calculating a black offset value for the one optical sensing element by using a least squares linear regression algorithm to fit the curve of the average white values into the range of the average black values of the plurality of optical sensing elements; and e) calibrating the one optical sensing element using at least the black offset value calculated in step d).