US Patent 7418114 Print tone measuring method

A print tone measuring method includes a reference paper image pickup step for reading an image of reference paper to obtain first image data, a designated control point setting step for setting designated control points, a first reference point setting step for setting a pair of first reference points for specifying image positions, a print reading step for reading an image of an actual print to obtain second image data, a second reference point setting step for setting a pair of second reference points corresponding to the first reference points, a calculating step for calculating positions of corresponding control points corresponding to the designated control points from the first reference points and the second reference points, an extracting step for extracting image data adjacent each of the designated control points and image data adjacent each of the corresponding control points, and a correcting step for correcting the position of each corresponding control point in the second image data by comparing the image data adjacent each designated control point and the image data adjacent each corresponding control point.