One embodiment comprises a system that stores a pre-defined color conversion table and a hash table. The system receives user-defined color conversions for a print job, stores them in first locations in the hash table, and marks the first locations as persistent. The system processes the print job utilizing the color conversion table to convert colors in the print job to the output color space, and responsive to encountering colors in the print job that do not have color conversions in the color conversion table, interpolates between color conversions in the color conversion table to generate new color conversions, stores the new color conversions in second locations in the hash table, and marks the second locations as non-persistent. The system determines that the hash table is to be re-initialized, allows reuse of the second locations in the hash table, and prevents reuse of the first locations in the hash table.

An image processing apparatus includes circuitry that estimates a first geometric transformation parameter for aligning first output image data with the original image data, the first output image data being acquired by reading a first output result, and a second geometric transformation parameter for aligning second output image data with the original image data, the second output image data being acquired by reading a second output result; associates, based on the first and the second geometric transformation parameters, combinations of color components of the first and the second output image data, corresponding to pixels of the original image data, to generate pixel value association data; determines, based on the pixel value association data, a mapping for estimating color drift between the first output image data and the second output image data from the original image data; and subjects the original image data to color conversion based on the mapping.

Embodiments relate to pixel conversion of images for display. A circuit converts input pixel values of an image using a color conversion function. The circuit is operable in different modes where each mode uses a different color conversion function. A lookup table memory circuit stores a mapping of color converted values and input pixel values according to the mode of operation where the mapping represents the color conversion function associated with the mode. The circuit produces a color converted value from the lookup table as a color converted version of a first input pixel value responsive to the first input pixel value being within a first range. The circuit may also produce a color converted version of a second input pixel value by interpolating a subset of the color converted values received from the lookup table responsive to the second input pixel being within a second input range.

A color table is modulated. The color table includes a plurality of nodes, and each node corresponds with a color input in the first color space and provides a print output in a second color space. The set of the plurality of nodes are arranged in a vector of a first color perception parameter. The vector can be arranged according to an order of increasing second color perception parameter in the first color space to an end node of the set of the plurality of nodes. A node in the set of the plurality of nodes that provides a peak amount of the second color perception parameter on the medium is determined. The print output for the end node is replaced with a print output corresponding with the node that provides the peak amount of the second color perception parameter on the medium.

An information processing apparatus includes: a processor configured to execute a first smoothing process of smoothing a black component of a color conversion table, calculate other color components of the color conversion table using the black component for which the first smoothing process is executed, and execute a first update process of updating the color conversion table based on the black component for which the first smoothing process is executed and the calculated other color components.

An image processing apparatus comprises a unit configured to set a color selected by a user from among colors included in scanned image data obtained by reading a reference sample as a destination color for the adjustment-target color. Then, the unit configured to set a destination color has a function to set the destination color based on first scanned image data obtained by reading a color sample as the reference sample, in which patches of a plurality of colors including colors around the adjustment-target color are printed and a function to set the destination color based on second scanned image data obtained by reading a sample document.

An information processing apparatus (10) for evaluating the chromatic discriminability of content includes: a unit (S12) that converts the color space values of each of first and second verification points A and B on the content into Lab color space values; a unit (S13) that calculates the color difference and the lightness difference between the first and second verification points based on the Lab color space values; and a unit (S23, S24) that determines color-difference discriminability by comparing the color difference between the first and second verification points with a color-difference threshold, and determines lightness-difference discriminability by comparing the lightness difference between the first and second verification points with a lightness-difference threshold. Each of the color-difference threshold and the lightness-difference threshold is set to a value that depends on whether a region containing the first verification point and a region containing the second verification point are adjoining or not.

A print calibration system comprising a printing device to apply print material to a print target in a printing process, a memory for storing a lookup table; and a processor. The processor causes the printing device to print calibration points for reproducing a color ramp, by receiving a plurality of Neugebauer Primary area coverage (‘NPac’) points representing the plurality of calibration points and determining a hue angle and color space based on the NPac points. A plurality of nodes distributed between a first node and a second node of a sectional representation of the NPac points is determined. A lookup table is generated based on a relationship between the plurality of nodes and the NPac points for use during the printing process, wherein the lookup table comprises values to map between a first color space and a second color space, the lookup table is then provided to the printing device.

Certain examples described herein relate to color spaces. In some cases, data representing a set of color values is obtained. Each color value has, for each of first, second and third axes defining a three-dimensional color space, a respective coordinate value. In some cases, for each of the set of color values, the coordinate value for the first and/or second axis is transformed dependent on the coordinate value for the third axis, to generate data representing a transformed set of color values. A set of output color values in an output color space is derived using the generated data. Output data associating the set of output color values in the output color space with a set of further color values in a further color space is generated.

Target color table generated from source color tables. A first significance factor is assigned to a first node in a first source color table. The first node in the first source color table corresponds with a color input in a first color space and provides a first print substance formulation in a second color space. A second significance factor is assigned to a second node in a second source color table. The second node in the second source color table corresponds with the color input in the first color space and provides a second print substance formulation in the second color space. A third node in target color table is generated from the first and second nodes based on the first and second significance factors. The third node corresponds with the color input in the first color space and provides a third print substance formulation in the second color space.