Color converter, color conversion method, and recording medium

A color conversion method for converting an input color value to one of a plurality of representative color values within a constant hue plane and using the converted color value as a printing color value for a printing device, the method comprising:

• a printing color value determining step of determining the printing color value in a Voronoi diagram whose generatrixes are the representative color values in a device-independent color space;
• and
• a determination color value calculating step of calculating a determination color value showing a color value for determining the printing color value, wherein
• the determination color value calculating step is a step of determining, as a determination peak value, a color value having a lightness equal to that of an input peak value showing a maximum color value of saturation in a constant hue plane of the input color value and also having a hue and a saturation equal to those of a representative peak value showing a maximum color value of saturation in a constant hue plane of the representative color values,
• the determination color value calculating step is a step of calculating the determination color value in such a way that a positional relationship of the input color value relative to the input peak value, a white color value showing a color value of white, and a black color value showing a color value of black is equal to a positional relationship of the determination color value relative to the determination peak value, the white color value, and the black color value, and
• the printing color value determining step is a step of determining, as the printing color value, the representative color value closest to the determination color value calculated in the determination color value calculating step in the Voronoi diagram.

A non-transitory computer-readable recording medium capable of storing a color conversion program executable by a computer, wherein

• the color conversion program is a color conversion program for converting an input color value to one of a plurality of representative color values within a constant hue plane and using the converted color value as a printing color value for a printing device,
• the color conversion program causes the computer to function as a printing color value determining unit that determines the printing color value in a Voronoi diagram whose generatrixes are the representative color values in a device-independent color space, and as a determination color value calculating unit that calculates a determination color value showing a color value for determining the printing color value,
• the determination color value calculating unit determines, as a determination peak value, a color value having a lightness equal to that of an input peak value showing a maximum color value of saturation in a constant hue plane of the input color value and also having a hue and a saturation equal to those of a representative peak value showing a maximum color value of saturation in a constant hue plane of the representative color values,
• the determination color value calculating unit calculates the determination color value in such a way that a positional relationship of the input color value relative to the input peak value, a white color value showing a color value of white, and a black color value showing a color value of black is equal to a positional relationship of the determination color value relative to the determination peak value, the white color value, and the black color value, and
• the printing color value determining unit determines, as the printing color value, the representative color value closest to the determination color value calculated by the determination color value calculating unit in the Voronoi diagram.