Abstract: Certain examples described herein relate to halftone level adjustment for Neugebauer Primaries (NPs). In certain examples, halftone levels for NPs are obtained for a halftone for printing an image. It is determined whether the halftone corresponds to a line or an area fill. The halftone levels may be adjusted in response to these levels exceeding a printing attribute threshold. The printing attribute threshold may be dependent on whether the halftone corresponds to a line or an area fill. The image may then be printed using the adjusted halftone levels.

Abstract: Mask entries for each of a plurality of passes over which print fluid drops are to be dispensed for printing an image are generated based on different types of masks and based on image data for the image. Print fluid drop dispensation for a pixel for which the mask entries for a given pass specify repeated print fluid drop dispensation is moved to a mask entry for an adjacent pass that does not specify print fluid drop dispensation for the pixel. Ejection of print fluid to print the image is caused based on the generated mask entries.

Abstract: A system encodes a plurality of colorant vectors of a printer in a Neugebauer Primary area coverage (NPac) vector for use in selecting colorants to output an image by the printer. The encoding includes using a function that relates the plurality of colorant vectors to an NP matrix including a plurality of sets of NPs that correspond to different colorant vectors of the plurality of colorant vectors, and determining the NPac vector based on achieving an objective for the function.

Abstract: Certain examples described herein relate to halftone level adjustment for Neugebauer Primaries (NPs). In certain examples, halftone levels for NPs are obtained for a halftone for printing an image. It is determined whether the halftone corresponds to a line or an area fill. The halftone levels may be adjusted in response to these levels exceeding a printing attribute threshold. The printing attribute threshold may be dependent on whether the halftone corresponds to a line or an area fill. The image may then be printed using the adjusted halftone levels.

Abstract: In some examples, a system receives image data for printing by a printer, and for a given colorant of a plurality of colorants to be used to print an image based on the image data, selects a plurality of different types of masks to use when dispensing printing fluid drops of the given colorant when printing the image. The system generates control data for printing the image using the selected plurality of different types of masks.

Abstract: Certain examples described herein relate to mapping between an input color space and an output color space. In some cases, data representing a set of candidate output color values in the output color space is obtained for a transition region between two input color values in the input color space. A sub-region of the transition region is defined, the sub-region being associated with a target colorimetry and a target value of a metric. An output color value is selected from the set of candidate output color values. The output value has an associated value of the metric and an associated colorimetry. The selecting is based on the associated colorimetry and the target colorimetry, and the value of the metric and the target value of the metric. In some cases, mapping data is generated by assigning the selected output color value to the sub-region.

Abstract: A hybrid-masked halftone area Neugebauer separation (HANS) pipeline for a printing system is constructed. A number of Neugebauer Primaries (NPs) of and a halftone pattern to employ within the pipeline are selected according to specified ink interaction constraints during printing system ink output onto media, at a native resolution of the printing system. An NP area coverage (NPac)-based lookup table (LUT) and a pre-LUT color profile to employ within the pipeline are constructed according to first specified ink coverage and usage constraints during the ink output, at the native resolution. LUT post-processing and post-halftone pattern masking to employ within the pipeline are determined according to second specified ink coverage and usage constraints during the ink output, at the native resolution.

Abstract: Certain examples described herein relate to printer calibration. In some cases, adjustment data is received, indicating an adjustment to be applied to a given colorant. A Neugebauer Primary area coverage (NPac) vector defining an operating set of Neugebauer Primaries (NPs) is obtained. Configuration data is determined, dependent on the operating set of NPs. The configuration data maps colorant adjustments to relationships between NPs in the operating set, for both an increase and a decrease in the given colorant. In some cases, the configuration data and the adjustment parameters are used to identify first and second subsets of the operating set of NPs. The NPac vector is adjusted by decreasing an area coverage of an NP in the first subset and complementarily increasing an area coverage of an NP in the second subset.

Abstract: In an example, a method includes acquiring data representing an article to be printed, the data comprising an element set associated with a print addressable location, the element set comprising a first element subset and a second element subset, wherein the first element subset and the second element subset comprise an element identifying a print material selection which is associated with a probability that the print material selection is to be applied to the associated print addressable location. The method further includes determining a first set of cumulative probability values associated with the elements of the first element subset and determining a second set of cumulative probability values associated with the elements of the second element subset. The first set of cumulative probability values may span a first predetermined value range and the second set of cumulative probability values may span a second predetermined value range.

Abstract: Certain examples relate to configuring a print processing system to produce rendered color outputs based on desired properties of said outputs using resources available to the print processing system. In these examples, print job data is received comprising image data and print property data. Color mapping data is configured to produce print mapping data based on at least the print property data. Print instructions for an image rendering device are generated based on the print mapping data. The print properties may be selectable by a user. Color mapping data may be characterized by color properties.

Abstract: 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.

Abstract: 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.

Abstract: Certain examples relate to configuring a print processing system to produce rendered color outputs based on desired properties of said outputs using resources available to the print processing system. In these examples, print job data is received comprising image data and print property data. Color mapping data is configured to produce print mapping data based on at least the print property data. Print instructions for an image rendering device are generated based on the print mapping data. The print properties may be selectable by a user. Color mapping data may be characterized by color properties.

Abstract: Certain examples described herein relate to updating a lookup table for an imaging system. An initial lookup table for an imaging system is obtained, the initial lookup table mapping between a first color space and a second color space. A smoothed version of the initial lookup table is also obtained. Further obtained are color property values corresponding to nodes of the lookup tables that map from a vertex-to-vertex axis of the first color space. The color property values are derived from measurements of test areas rendered by the imaging system. For a target node of the smoothed version of the initial lookup table that maps from the vertex-to-vertex axis, a pair of nodes in the initial lookup table are selected based on the obtained color property values. A mapped value in the second color space for the target node is updated, based on an interpolation of mapped values for the pair of nodes in the initial lookup table.

Abstract: In an example a method includes deriving a print agent coverage vector specifying an area coverage for each of a plurality of elements, wherein each element is associated with a print agent, a print agent combination or an absence of print agent. Deriving the print agent coverage vector comprises, for a first element of the print agent coverage vector, applying a first weighting function which varies based on an intended area color value.

Abstract: A computing device receives first data indicating a first metric of a first printed test area and second data indicating a second metric of a second printed test area. The first printed test area is associated with a first plurality of Neugebauer Primaries and each Neugebauer Primary in the first plurality of Neugebauer Primaries is associated with a respective area coverage in the first printed test area. The second printed test area is associated with a second plurality of Neugebauer Primaries, wherein each Neugebauer Primary in the second plurality of Neugebauer Primaries is associated with a respective area coverage in the second printed test area and the second plurality of Neugebauer Primaries is different from the first plurality of Neugebauer Primaries. The computing device generates third data associating a color in a color space with the first plurality of Neugebauer Primaries or the second plurality of Neugebauer Primaries in dependence on the first metric and the second metric.

Abstract: In an example, a method includes acquiring data representing an article to be printed, the data comprising an element set associated with a print addressable location, the element set comprising a first element subset and a second element subset, wherein the first element subset and the second element subset comprise an element identifying a print material selection which is associated en with a probability that the print material selection is to be applied to the associated print addressable location. The method further includes determining a first set of cumulative probability values associated with the elements of the first element subset and determining a second set of cumulative probability values associated with the elements of the second element subset. The first set of cumulative probability values may span a first predetermined value range and the second set of cumulative probability values may span a second predetermined value range.

Abstract: A computing device receives first data indicating a first metric of a first printed test area and second data indicating a second metric of a second printed test area. The first printed test area is associated with a first plurality of Neugebauer Primaries and each Neugebauer Primary in the first plurality of Neugebauer Primaries is associated with a respective area coverage in the first printed test area. The second printed test area is associated with a second plurality of Neugebauer Primaries, wherein each Neugebauer Primary in the second plurality of Neugebauer Primaries is associated with a respective area coverage in the second printed test area and the second plurality of Neugebauer Primaries is different from the first plurality of Neugebauer Primaries. The computing device generates third data associating a color in a color space with the first plurality of Neugebauer Primaries or the second plurality of Neugebauer Primaries in dependence on the first metric and the second metric.

Abstract: Certain examples described herein relate to mapping between an input color space and an output color space. In some cases, data representing a set of candidate output color values in the output color space is obtained for a transition region between two input color values in the input color space. A sub-region of the transition region is defined, the sub-region being associated with a target colorimetry and a target value of a metric. An output color value is selected from the set of candidate output color values. The output value has an associated value of the metric and an associated colorimetry. The selecting is based on the associated colorimetry and the target colorimetry, and the value of the metric and the target value of the metric. In some cases, mapping data is generated by assigning the selected output color value to the sub-region.

Abstract: A method of obtaining a calibration factor for color calibration of a printing system. The method includes printing, using the printing system, a plurality of Neugebauer primaries (NPs) each defined by a respective Neugebauer primary area coverage (NPac) vector. For each of the NPs, an area coverage change of the NP is determined from a measurement of a visual property for the NP and a measurement of the visual property for a corresponding reference NP corresponding to the respective NPac vector. The calibration N factor for the printing system is obtained based on the area coverage change for respective NPs of the plurality of NPs.