Color conversion lut generating device, color conversion lut generation method, color conversion processing device, color conversion processing method, and storage medium

A color conversion look up table for converting input image signal values into output values of actual color materials installed in an image forming device,

• wherein, in axes corresponding primary colors indicating the output values corresponding to the input image signal values using a light color material and a shade color material,
• the number of grid points is smaller than the number of input image signal values,
• the grid points are arranged at equal intervals,
• the light color material corresponds to a small value of the input image signal,
• the output value of the light color material reaches an inflection point before reaching a maximum value which the light color material is able to reach,
• the shade color material corresponds to the input image signal values at an inflection point of the shade color material, and
• each of the inflection point of the output value of the light color material and the inflection point of the output value of the shade color material coincides with any one of the grid points.

A color conversion LUT generation method that generates a first color conversion LUT for converting an input image signal value into an output value of an actual color material installed in an image forming device,

• the first color conversion LUT being a look up table obtained by thinning out grid points in a second color conversion LUT in which the number of grid points is larger than the number of grid points of the first color conversion LUT, the color conversion LUT generation method comprising:
• an acquisition step of acquiring grid point position information indicating positions of the grid points in the first color conversion LUT;
• and
• a generation step of generating the first color conversion LUT on the basis of the grid point position information,
• wherein the generating steps includes determining whether or not an inflection point of an output value of the actual color material is at a position of the grid point, correcting at least some output values for at least two actual color materials in the second color conversion LUT in accordance with a determination result, and generating the first color conversion LUT obtained by thinning out the grid points in the second color conversion LUT.

A non-transitory computer readable storage medium storing a program for causing a computer to function as a generating device that generates a first color conversion LUT for converting an input image signal value into an output value of an actual color material installed in an image forming device,

• the first color conversion LUT being a look up table obtained by thinning out grid points in a second color conversion LUT in which the number of grid points is larger than the number of grid points of the first color conversion LUT, the generating device comprising:
• an acquiring unit configured to acquire grid point position information indicating positions of the grid points in the first color conversion LUT;
• and
• a generating unit configured to generate the first color conversion LUT on the basis of the grid point position information,
• wherein the generating unit determines whether or not an inflection point of an output value of the actual color material is at a position of the grid point, corrects at least some output values for at least two actual color materials in the second color conversion LUT in accordance with a determination result, and generates the first color conversion LUT obtained by thinning out the grid points in the second color conversion LUT.