Color processing apparatus and color processing method

A color processing method of performing color conversion using a color conversion table which has signal values of an output color space corresponding to grid points dividing an input color space into a plurality of unit cubes, the method comprising:

• using a processor to perform steps of:
• determining a quadrant to which an input signal belongs, in a chromaticity plane perpendicular to a lightness axis of the input color space;
• detecting a unit cube to which the input signal belongs in the plurality of unit cubes;
• and
• dividing the detected unit cube into a plurality of polyhedrons for an interpolation operation by a segmentation method corresponding to the determined quadrant, wherein the dividing of the detected unit cube is performed along a direction of a diagonal line, which passes through an origin of the chromaticity plane, in a part of the plurality of unit cubes in accordance with the segmentation method.

A non-transitory computer readable medium storing a computer-executable program for causing a computer to perform a color processing method of performing color conversion using a color conversion table which has signal values of an output color space corresponding to grid points dividing an input color space into a plurality of unit cubes, the method comprising:

• determining a quadrant to which an input signal belongs, in a chromaticity plane perpendicular to a lightness axis of the input color space;
• detecting a unit cube to which the input signal belongs in the plurality of unit cubes;
• and
• dividing the detected unit cube into a plurality of polyhedrons for an interpolation operation by a segmentation method corresponding to the determined quadrant, wherein the dividing of the detected unit cube is performed along a direction of a diagonal line, which passes through an origin of the chromaticity plane, in a part of the plurality of unit cubes in accordance with the segmentation method.

A color processing apparatus for performing color conversion using a color conversion table which has signal values of an output color space corresponding to grid points dividing an input color space into a plurality of unit cubes, the apparatus comprising:

• one or more processors;
• and
• a memory coupled to the one or more processors and having stored thereon instructions, which, when executed by the one or more processors, cause the color processing apparatus to:
• determine a quadrant to which an input signal belongs, in a chromaticity plane perpendicular to a lightness axis of the input color space;
• detect a unit cube to which the input signal belongs in the plurality of unit cubes;
• and
• output an output signal corresponding to the input signal by an interpolation operation, which is based on the determined quadrant, using the signal values of the output color space,
• wherein the signal values of the output color space for the interpolation operation are, in a case where the unit cube to which the input signal belongs is divided into a plurality of polyhedrons along a direction of a diagonal line, which passes through an origin of the chromaticity plane, in a part of the plurality of unit cubes in accordance with a segmentation method corresponding to the determined quadrant, the signal values of the output color space corresponding to vertices of a polyhedron to which the input signal belongs in the plurality of polyhedrons.