The invention relates to a process for producing a printed image on a substrate comprising the steps of selecting eight or fewer process colors from a known process ink color set; providing two or more spot colors, forming a color set comprising the process colors and the spot colors; and optionally printing the image using the formed color set. The ratio of the number of spot colors to the number of process colors is at least 0.5:1.

This disclosure relates to a wide gamut encoder capable of receiving a wide gamut color image in accordance with a wide gamut standard. The encoder can encode one or more wide gamut color image pixel values into portions of narrow gamut encoding elements for transmission to a video encoder. The encoder can implement an advanced extended YCC format that is backward compatible with a P3 color gamut.

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.

Embodiments described herein provide for the reuse of some locations in a hash table of color conversions during processing of a print job, while preventing the reuse of other locations. If a determination is made that the hash table is to be re-initialized, then the locations in the hash table that are marked as non-persistent are marked as saved to allow them to be reused, while the locations in the hash table that are marked as persistent are prevented from being reused. During processing of the print job subsequent to re-initialization of the hash table, if a color in the print job does not have a color conversion, then a location in the hash table is identified that is marked as saved. If the location stores the color conversion for the color, then the non-persistent mark is restored for the location to bypass performing a color conversion for the color.

A method comprising: applying color correction to colors in a first color gamut; displaying, on color space, the second color gamut and color gamut in which the correction is applied to the first color gamut so as to make it possible to distinguish between colors constituting the first color gamut that are determined to be inside of the second color gamut and colors constituting the first color gamut that are determined to be outside of the second color gamut; selecting colors in colors outside of the displayed second color gamut; displaying an interface; determining a correction amount of the selected color in conjunction with the interface; when the selected color is on surface/inside of the second color gamut, displaying that the selected color is on surface/inside of the second color gamut; and applying the correction and generating color conversion information for converting the first color gamut into the second color gamut.

Certain examples described herein relate to color spaces. In some cases, first and second sets of output color values representable in an output color space are obtained. The first and second sets of output color values correspond to first and second operating states of a printing system respectively. Each output color value in the first and second sets has corresponding coordinates in a colorimetry space. The first and second sets of output color values define respective first and second gamuts in the colorimetry space. First and second colorimetry values in an intersection of the first and second gamuts in the colorimetry space are selected, the selecting based on the respective colorimetry of the first and second colorimetry values and a predetermined transition region in an input color space. For an input color value located in the predetermined transition region of the input color space, a corresponding target colorimetry value located between the first and second colorimetry values in the colorimetry space is obtained. First and second output color values are derived based on the target colorimetry value and the first and second sets of output color values, respectively. First and second mappings between the input color space and the output color space are generated by respectively assigning the first and second output color values to the input color value.

In one embodiment, a computing system may receive a target color and a propagated error for a pixel location. The system may determine an error-modified target color for the pixel location based on the received target color and the propagated error. The system may identify, based on a location of the error-modified target color in a three-dimensional color space, a subset of pre-determined colors in the three-dimensional color space. The error-modified target color may correspond to a weighted combination of the subset of pre-determined colors. The system may determine a pixel color for the pixel location based on the subset of pre-determined colors and respective weights associated with the subset of pre-determined colors. The system may determine, based on the pixel color, driving signals for light-emitting elements associated with the pixel location. The system may output the driving signals to control the light-emitting elements associated with the pixel location.

A gradation pattern image is determined in accordance with an image formation mode acquired when printing of a predetermined number of pages has been performed. A color gradation pattern image is formed when a color image formation mode has been acquired, whereas a monochrome gradation pattern image is formed when a monochrome image formation mode has been acquired.

An image reproduction system and methods for providing colorant data to an end device. A method includes extracting general HSV value data for each pixel of an image from image data. For each pixel, the general HSV value data is transformed to generate universal perceived brightness, Bp, and universal perceived-chroma, Cp, value data. End-device colorant data associated with the general HSV value data is retrieved for each pixel and scaled using the Bp and Cp value data to obtain scaled end-device colorant data. The scaled end-device colorant data is transmitted to the end device.

A method for building a security image for a security structure of a security document from multiplexing color images, including selecting a marking method capable of producing sets of colors on the security document comprising different colors that can be displayed according to illumination/observation modes of the security structure, establishing a plurality of color sets that can be displayed by the security structure in a plurality of the different illumination/observation modes, distributing the color sets in a plurality of groups of color sets, establishing combinations of groups of color sets having at least one color set in common across the number of different illumination/observation modes, selecting a combination of a group of color sets based on the number of desired illumination/observation modes and the number of colors per color image, and determining the color images to multiplex by means of the combination of the group of color sets selected.