Color conversion method, color conversion device, and non-transitory computer-readable storage medium storing program

A color conversion device comprising:

• a selection unit configured to receive an instruction to hold black print;
• a table creation unit configured to create a color conversion table defining an association between an input value in an input color space in image data and an output value in an output color space in a printing device that prints an image represented by the image data;
• and
• a correction unit configured to
• when the instruction is received and a single-color input value that is the input value including only a K component in the image data is converted into the output value including a non-target color component that is a color component other than the K component by color conversion using the color conversion table,
• execute black print holding correction for correcting the color conversion table to increase the K component and decrease the non-target color component in the output value associated with a target grid point that is a grid point representing the single-color input value in the color conversion table, and
• execute spread correction for spreading the black print holding correction to a spread grid point in a predetermined range around the target grid point among grid points representing the input value in the color conversion table, which is spread correction for correcting the output value associated with the spread grid point in the color conversion table by using an increase amount of the K component caused by the black print holding correction and a substitution rate table in which a color component substitution rate is defined for the non-target color component to limit a color variation caused by the spread correction.

A non-transitory computer-readable storage medium storing a program for causing a computer to execute:

• a function of receiving an instruction to hold black print;
• a function of creating a color conversion table defining an association between an input value in an input color space in image data and an output value in an output color space in a printing device that prints an image represented by the image data;
• and
• when the instruction is received and a single-color input value that is the input value including only a K component in the image data is converted into the output value including a non-target color component that is a color component other than the K component by color conversion using the color conversion table,
• a function of executing black print holding correction for correcting the color conversion table to increase the K component and decrease the non-target color component in the output value associated with a target grid point that is a grid point representing the single-color input value in the color conversion table, and
• a function of executing spread correction for spreading the black print holding correction to a spread grid point in a predetermined range around the target grid point among grid points representing the input value in the color conversion table, which is spread correction for correcting the output value associated with the spread grid point in the color conversion table by using an increase amount of the K component caused by the black print holding correction and a substitution rate table in which a color component substitution rate is defined for the non-target color component to limit a color variation caused by the spread correction.