Patent ID: 7995240
Filing Date: 2011-08-09
Classification: G03G

Abstract:
1. An image-forming device comprising: an image-forming unit capable of forming, for one color, an image based on image data indicating a density falling within a predetermined density range, a plurality of different densities being defined within the density range and a plurality of different reference densities being defined among the plurality of densities within the density range, the image-forming unit being capable of forming a plurality of density patches corresponding to the plurality of reference densities; a sensor detecting the densities of the density patches formed by the image-forming unit and outputting a measured output value for each reference density; a storing unit storing reference output values for the reference densities; a reference ratio determining unit determining reference ratios to compensate for differences between the measured output values and the reference output values for the reference densities; an estimated ratio determining unit determining estimated ratios corresponding to densities other than the reference densities based on the reference ratios for the reference densities; and a density correcting unit correcting density of image data based on the reference ratios and estimated ratios, the density-corrected image data being supplied to the image-forming unit, the image-forming unit forming an image based on the density-corrected image data; wherein the storing unit further stores a correction table that stores, for the one color, correction output values in correspondence with all the plurality of densities in the density range, wherein the image-forming unit forms the plurality of density patches for the one color based on the plurality of different reference densities by correcting the reference densities into correction output values that correspond to the reference densities in the correction table, wherein the reference ratio determining unit includes: wherein the density range has a predetermined minimum density and a predetermined maximum density, the plurality of different reference densities being different from the predetermined minimum density and the predetermined maximum density, the plurality of different reference densities including a first reference density and a second reference density, the first reference density being different from but being the nearest to the minimum density among the plurality of different reference densities, the second reference density being different from but being the nearest to the maximum density among the plurality of different reference densities; and wherein the estimated ratio determining unit sets the estimated ratios for those densities that are other than the reference densities and that exist within a part of the density range that is defined between the first reference density and the second reference density using a curve approximation based on the reference ratios calculated for the plurality of different reference densities.