Canon Kabushiki Kaisha

Mayuko Kishino

Shinichi Miyazaki

Toshiki Miyazaki

Takahisa Akaishi

An apparatus sets a chromaticity point serving as a gray reference in a color gamut of a color space that an output device is able to output, specifies, in the color gamut of the color space that the output device is able to output, a first minimum lightness point on a lightness axis of the set chromaticity point and a second minimum lightness point that is achromatic, and generates a gray line that passes through a black point that is a minimum lightness point on a line connecting the first minimum lightness point and the second minimum lightness point, the first minimum lightness point, and the set chromaticity point and reaches a white point in the color gamut of the color space that the output device is able to output.

Image processing apparatus and method

A color gamut for each printing mode is maximally used, a color separation table is used, which includes an area (color reproduction maintaining area) for which an image having a color difference of a predetermined value or less between printing modes in a case where the same input value is input is output and an area (area other than the color reproduction maintaining area) for which an image having a color difference of a predetermined value or more between the printing modes in a case where the same input value is input is output. From this, a color matching table can be shared between the printing modes.

Image processing method and apparatus, and color separation table generating method optimizing color gamut for each printing mode

When a grid point that is the object to be mapped is present in a first division region a color of which has lightness equal to or higher than the lightness at the maximum chroma point in the color gamut and has chroma higher than the chroma at that point, the intersection of a straight line connecting the grid point to the maximum chroma point and an achromatic axis is calculated and a point having lightness equal to or higher than the lightness of the intersection is set as the focal color. Then, the intersection of a straight line connecting the object grid point to the focal color and the boundary of color gamut is set as an output color for the grid point. The output colors are prevented from being separated into color on the high and on the low lightness sides with respect to the maximum chroma point.

Image processing apparatus and profile generation method

With an apparatus according to the present invention, when an input color gamut is compressed to an output color gamut, based on the difference value between the lightness of paper white and the lightness at the maximum chroma in the output color gamut of a predetermined hue, if the lightness difference is below a predetermined threshold value, a compression convergence point is set at a position at which lightness is lower than or equal to the lightness at the maximum chroma in the output color gamut. This suppresses reduction of the gradation in the direction of input chroma, and makes it possible to compress the input color gamut to the output color gamut such that excellent color reproduction is achieved while the gradations of lightness and chroma in the input color space are maintained.

Growing community of inventors

Tokyo, Japan

Mayuko Kishino