Patent ID: 8482794

Claim:
An image processing apparatus, comprising: a printing unit configured to print a plurality of patch images having different frequency characteristics; a first reading unit configured to read the plurality of patch images printed by the printing unit, the patch images having the different frequency characteristics; a first spatial frequency conversion unit configured to perform spatial frequency conversion on the plurality of patch images having been read by the first reading unit; a determination unit configured to determine a patch image to be used for spatial frequency correction among the plurality of patch images based on amounts of change in respective spatial frequency responses of the plurality of patch images between before and after the spatial frequency conversion performed by the first spatial frequency conversion unit; a second reading unit configured to read the plurality of patch images printed by the printing unit; a second spatial frequency conversion unit configured to perform spatial frequency conversion on the plurality of images having been read by the second reading unit; and a calculation unit configured to calculate correction amounts for conversion by the first and second spatial frequency conversion units, according to a difference between (a) a spatial frequency response of the patch image determined by the determination unit among the plurality of patch images having been read by the first reading unit and having been converted by the first spatial frequency conversion unit, and (b) a spatial frequency response of the patch image determined by the determination unit among the plurality of patch images having been read by the second reading unit and having been converted by the second spatial frequency conversion unit, the calculation unit calculating the correction amounts such that both spatial frequency responses become comparable with each other.