Patent ID: 9258457
Filing Date: 2016-02-09
CPC Classification: B41J,G03G,G06K,H04N

Claim Text:
1. A gamma correction table generation method of measuring a density patch output by an image forming device based on a dot pattern expressing a pseudo tone according to a number of black pixels included in each cell composed of a plurality of pixels, the gamma correction table generation method including steps of: obtaining density information by reading, with a reading sensor in a range wider than a cell, a plurality of density patches each corresponding to a tone, wherein the density patches each includes a plurality of cells, wherein the cells included in the density patches each includes a number of black pixels according to a corresponding tone, wherein the black pixels in each of the cells are arranged at same positions in each of the cells and the plurality of cells is periodically arranged, wherein in a case where a density patch of the plurality of density patches corresponds to a predetermined tone or more, the density patch is an image of a dot pattern in which the plurality of cells is arranged such that pixels included in the cells do not overlap pixels included in adjacent cells and a distance between dots formed by the black pixels included in the cells is a predetermined distance, and wherein in a case where a density patch of the plurality of density patches corresponds to less than a predetermined tone, the density patch is an image of a dot pattern in which a plurality of cells is arranged such that some pixels included in a cell overlap some pixels in an adjacent cell so that the black pixels included in each of the cells are separated from the black pixels in adjacent cells to an extent that a shape of a dot formed by the black pixels included in each of the cells is maintained and such that a distance between dots in the cells is a distance shorter than the predetermined distance; correcting density information being obtained by measuring the density patch corresponding to less than a predetermined tone, in the density information according to a number of the cells in the density patch; and generating a gamma correction table based on density information on the density patch corresponding to the predetermined tone or more and the corrected density information.