SHADING CORRECTION DATA GENERATOR, WHITE SHADING CORRECTION DEVICE, IMAGE READER, IMAGE FORMING DEVICE, SHADING CORRECTION DATA GENERATING METHOD, PROGRAM AND STORAGE MEDIUM

摘要

PROBLEM TO BE SOLVED: To generate shading correction data with high accuracy taking into account deterioration in the scanning optical system. SOLUTION: An averaging circuit 29 applies averaging processing to m-lines image data read from a white reference board at a top in the subscanning direction to generate reference data. A gain setting circuit 71 sets an amplification factor of an amplifier of a signal processing circuit 22. A NOREF arithmetic circuit 72 acquires the amplification factor as information denoting a degree of deterioration in a scanning optical system. Then a setting value NOREF is obtained from the amplification factor. A comparator circuit 31 compares a value subtracting the setting value NOREF from data read from the white reference board after the reference data with read image data after the reference data. When the image data after the reference data are found to be smaller according to the comparison arithmetic operation, the image data after the reference data are excluded. Then shading correction data are generated by using the image data after the exclusion for the object.