To attain highly precise processing of automatic gradation correction by detecting a luminous quantity at a read position of a gradation pattern or in the vicinity of a read position so as to correct a read gradation pattern.
A signal from a scanner 401 is given to a shading correction circuit 402, in which dispersion in elements and uneven lighting by a light source are corrected and the result is converted into lightness data by an RGBγ correction circuit 403. An MTF correction circuit 405 corrects deterioration in an MTF characteristic of an input system. A color conversion UCR processing circuit 406 is made up of a color correction processing section that corrects a difference between a color separation characteristic of the input system and a color material spectral characteristic of an output system to calculate the quantity of the color material YMC and up of a UCR processing section that replaces an overlapped part of three YMC colors with a black color. A hue discrimination circuit 422 selects a color conversion coefficient in response to each hue. A gradation processing circuit 411 conducts dither processing or pattern processing. Then the image processing circuits as above are controlled by a CPU 415.
HAYASHI KOJI
NAKASHIGE FUMIHIRO
