US Patent 7667867 Printing apparatus and correction data generating method

A printing apparatus for measuring proper density and generating correction data with high accuracy by eliminating influences of adjoining areas. A plurality of scanning coordinates SAx are set to a middle position in a primary scanning direction of each of pixel lines Q on a test chart. Scanning areas SA are set to positions where the scanning coordinates SAx intersect scanning coordinates SAy indicating numerous positions in a secondary scanning direction of the pixel lines Q. Density data of the scanning areas SA is averaged to generate correction data for updating a correction table.