Color conversion in image processing apparatus, image processing method and information processing apparatus, control method thereof, and non-transitory computer-readable medium

An image processing method for an image processing apparatus comprising:

• obtaining a first signal that is a signal in a uniform color space by converting a signal corresponding to a predetermined color of an input image signal;
• obtaining a second signal that is a signal in a uniform color space by converting a signal corresponding to the predetermined color of a signal in a color space used by the image processing apparatus;
• deciding a grid point coordinate value on a lookup table that corresponds to the predetermined color;
• associating a signal of the predetermined color in the uniform color space that is obtained as the first signal, with the decided grid point coordinate value, and based on the association calculating a first matrix for converting each signal in the uniform color space into a grid point coordinate value;
• associating the signal of the predetermined color in the uniform color space that is obtained as the second signal, with the grid point coordinate value decided, and based on the association calculating a second matrix for converting each grid point coordinate value into a signal in the uniform color space;
• generating a lookup table for converting each grid point coordinate value into a signal in the color space used by the image processing apparatus by using the second matrix and color space information for converting a signal in the uniform color space into a signal in the color space used by the image processing apparatus;
• and
• converting the input image signal into the signal in the color space used by the image processing apparatus by using the first matrix and the lookup table, to print the converted input image signal.

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

• obtain a first signal that is a signal in a uniform color space by converting a signal corresponding to a predetermined color of an input image signal;
• obtain a second signal that is a signal in a uniform color space by converting a signal corresponding to the predetermined color of a signal in a color space used by the computer;
• decide a grid point coordinate value on a lookup table that corresponds to the predetermined color;
• associate a signal of the predetermined color in the uniform color space that is obtained as the first signal, with the decided grid point coordinate value, and based on the association calculate a first matrix for converting each signal in the uniform color space into a grid point coordinate value;
• associate the signal of the predetermined color in the uniform color space that is obtained as the second signal, with the grid point coordinate value decided, and based on the association calculate a second matrix for converting each grid point coordinate value into a signal in the uniform color space;
• generate a lookup table for converting each grid point coordinate value into a signal in the color space used by the computer by using the second matrix and color space information for converting a signal in the uniform color space into a signal in the color space used by the computer;
• and
• convert the input image signal into the signal in the color space used by the computer by using the first matrix and the lookup table, to print the converted input image signal.