According to this method, the mapping color LUT has input colors that sample not only a source color gamut (included in an input encoding color space in which inputs colors of this LUT are encoded) but also a portion of the input encoding color space which is not included in the source color gamut. Preferably, this color LUT further includes output colors located outside the target color gamut. Accuracy of the mapping is improved, notably for source colors located near the boundary of the source color gamut.

The processing of RGB image data can be optimized by performing optimization operations on the image data when it is converted into the YCbCr color space. First, a raw RGB color space is converted into a YCbCr color space, and raw RGB image data is converted into YCbCr image data using the YCbCr color space. For each Y-layer of the YCbCr image data, a 2D LUT is generated. The YCbCr image data is converted into optimized CbCr image data using the 2D LUTs, and optimized YCbCr image data is generated by blending CbCr image data corresponding to multiple Y-layers. The optimized YCbCr image data is converted into sRGB image data, and a tone curve is applied to the sRGB image data to produce optimized sRGB image data.

The processing of RGB image data can be optimized by performing optimization operations on the image data when it is converted into the YCbCr color space. First, a raw RGB color space is converted into a YCbCr color space, and raw RGB image data is converted into YCbCr image data using the YCbCr color space. For each Y-layer of the YCbCr image data, a 2D LUT is generated. The YCbCr image data is converted into optimized CbCr image data using the 2D LUTs, and optimized YCbCr image data is generated by blending CbCr image data corresponding to multiple Y-layers. The optimized YCbCr image data is converted into sRGB image data, and a tone curve is applied to the sRGB image data to produce optimized sRGB image data.

An image display apparatus includes: a light source unit including three or more light sources, combining lights from the light sources and emitting the combined light; a wavelength detector that detects, for each light source, wavelength information indicating the wavelength of light from the light source; a color value determiner that determines, for each light source, from the wavelength information, a color value indicating a color of light from the light source in a predetermined color space; a correction value determiner that determines, based on the color values, a correction value for correcting a ratio between the intensities of lights from the light sources so that the color of the combined light is a color to be displayed; and a driver that drives the light sources so that the ratio between the intensities of lights from the light sources is a ratio corrected based on the correction value.

A color image of a target is captured by a color sensor in an imaging reader. A color image processing pipeline processes the captured color image with a plurality of color image processing components to display the image of a target with high fidelity. One or more of the components are bypassed to decode the image of a symbol target to prevent degradation of reader performance.

An image reading apparatus includes a line sensor configured to read an image of a target object. The line sensor includes light receiving element arrays arranged at given intervals in a second direction perpendicular to a first direction for a plurality of lines, the plurality of light receiving element arrays each including a first light receiving element configured to receive light of a first color and a second light receiving element configured to receive light of a second color different from the first color, which are arranged in the first direction to form one line. The image reading apparatus is configured to derive a shading correction coefficient for shading correction based on output from the light receiving element arrays that have read a reference white plate, and to identify, as an abnormal pixel, a pixel obtained by reading a foreign matter existing on the reference white plate.

A printer includes: an inline scanner which acquires an RGB value of each patch of a color chart; an inline colorimeter which acquires a colorimetric value of each patch of the color chart; a profile creation unit which creates a profile for associating the RGB value with the colorimetric value of each patch; and a color conversion unit which estimates a colorimetric value corresponding to an RGB value of input data by extrapolation calculation using four points including three points forming a plane and one supporting point in data of the profile, wherein the color conversion unit estimates the colorimetric value corresponding to the RGB value based on a set of four points remained after deleting one or a plurality of sets of four points according to a predetermined rule from a plurality of sets of four points selected for an RGB value input.

A computer analyzes submitted data to identify insufficient data among data necessary for executing C×F color conversion process. When spectral characteristic data of a patch constituting a C×F chart is insufficient, a computer supplements the spectral characteristic data. When complete printing order data has not been obtained, the computer supplements printing order data. The color conversion process is performed using the data after supplement.

An image forming apparatus includes a table generating unit. The table generating unit, in a Voronoi diagram, obtains empty circles as circles centered at Voronoi seeds of ends of Voronoi sides that intersect with a straight line passing through a largest saturation color and a smallest-saturation and specific-lightness color and passes through generatrices. After the table generating unit sets one of the generatrices shared by the two adjacent empty circles whose radius ratio is outside a specific range as a target point, and causes the radius ratio of the two empty circles to be within the specific range by changing at least one radius of the two empty circles, the table generating unit generates the conversion table that sets a color that corresponds to an intersection point corresponding to the target point among the intersection points of the two empty circles, as the definition colors.

An image forming apparatus includes a table generating unit. The table generating unit determines whether a target-value Voronoi region and a measured-value Voronoi region are identical or not. The table generating unit sets an output color value associated with a print position where the target-value Voronoi region and the measured-value Voronoi region are identical in the second color conversion table as the output color value associated with a specific input color value in the first color conversion table. The table generating unit sets the output color value associated with the print position where the target-value Voronoi region and the measured-value Voronoi region are different in the second color conversion table as a color value that is a color value in the hue plane and is different from the output color value associated with the specific input color value in the first color conversion table.