Color conversion device, color conversion method and computer readable medium calculate a minimum required black amount in regard to colors that are reproduced by an output device that actually outputs

A color conversion device comprising:

• a forward converting unit that converts a target device color signal of an N-dimensional color space in a target output device that uses color materials of N colors including black, where N is an integer equal to or larger than 4, into a conversion target-independent color signal of a device-independent color space;
• a black amount determining unit that determines a black amount from the conversion target-independent color signal that has been converted by the forward converting unit, wherein a virtual plane color signal group creating unit that creates a lower outline color signal that satisfies the total amount limit value that has been calculated for each black amount on the basis of the limit value that has been set in accordance with the color gamut;
• an optimum black amount calculating unit that calculates an optimum black amount from the black amount that has been determined by the black amount determining unit and the black amount of a target device color signal;
• and
• an inverse converting unit that calculates color components from the optimum black amount and the conversion target-independent color signal, the color components being color components except black of an M-dimensional output color signal containing color materials of M color components including black, where M is an integer equal to or larger than 4, which is actually used by a target output device,
• wherein the color conversion device outputs an output color signal created by the color components and the optimum black amount,
• the black amount determining unit uses a model for calculating the black amount to determine the black amount from the conversion target-independent color signal,
• the model is created by an independent color signal in the device-independent color space calculated from the lower outline color signal and the black amount of the lower outline to which the independent color signal belongs,
• a lower outline color signal satisfies the calculated total amount limit value, and
• a total amount limit value is calculated in accordance with the color gamut for each black amount on the basis of a limit value in which an upper limit of a total amount of the color materials that are used in the target output device has been set in accordance with the color gamut.

A color conversion method, comprising:

• setting, in accordance with a color gamut, a limit value of a color material total amount that is used in an output device that uses color materials of M colors including black, where M is an integer equal to or larger than 4, and outputs an image;
• and
• calculating a total amount limit value corresponding to the color gamut for each black amount on the basis of the limit value that has been set in accordance with the color gamut by the limit value setting,
• and determining a black amount from a conversion target-independent color signal of a device-independent color space, wherein the black amount determining includes
• creating a lower outline color signal that satisfies the total amount limit value that has been calculated for each black amount on the basis of the limit value that has been set in accordance with the color gamut.