Abstract: Certain examples described herein relate to the control of colorants and treatments for printing. In certain examples image data, a colorant color mapping and one or more treatment color mappings is obtained. The colorant color mapping may be used to map the image data to colorant application values. The one or more treatment color mappings may be used to map the image data to treatment application values. The colorant application values and treatment application values may be used to generate discrete print control instructions to apply the set of colorants and set of treatments to a printing substrate.

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: 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: A method is disclosed. According to some examples, the method comprises determining, by processing circuitry, a first element set to be associated with a print addressable location, the first element set comprising a first plurality of elements, wherein each element of the first plurality of elements identifies a print colorant or print colorant combination and is associated with a probability that the print colorant or print colorant combination identified by that element is to be applied to the associated print addressable location.

Abstract: In an example, a method includes determining, by processing circuitry, an element set to be associated with a print addressable location for printing an article in a one-pass print mode. The element set may comprise a plurality of elements, wherein each element identifies a print material or print material combination and is associated with a probability that the print material or print material combination identified by that element is to be applied to the associated print addressable location. Determining the element set for printing in a one-pass print mode may comprise favouring elements identifying individual print materials over elements identifying print material combinations.

Abstract: Certain examples described herein relate to adjusting a printing system. In certain cases, a lookup table, LUT, is obtained where the lookup table comprises a plurality of nodes that map a plurality of input first color space values to a plurality of Neugebauer Primary area coverage, NPac, vectors in a second color space and each NPac vector comprises at least one Neugebauer Primary, NP. Each NPac vector in the LUT is adjusted by the determination of a colorimetric value of the NPac vector and the modification of the NPac vector based on a characteristic of the corresponding at least one NP and the colorimetric value such that the modification is specific to the NPac vector. The lookup table is updated with the modified NPac vector and stored for referral by the printing system in any future printing.

Abstract: In an example, a method includes accessing an initial prediction of a granularity metric for a halftone pattern. A correction factor to apply to the initial prediction may be determined, the correction factor being determined from a correction factor model defining a relationship between initial predictions of granularity metrics and human perceptions of granularity. The method may further include generating, using processing circuitry, a revised prediction of the granularity metric for the halftone pattern using the correction factor.

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: In an example, a method includes determining, using processing circuitry, a first and second set of print agent coverage vectors characterising a white to black neutral axis in a color space. The first set of print agent coverage vectors may comprise non-black colorant elements and no black colorant elements, and the second set of print agent coverage vectors may comprise black colorant elements and no non-black colorant elements. Print agent coverage vectors characterising a skeleton of a color gamut using the non-black colorants and no black colorants and including the first set of print agent coverage vectors may also be determined, and a third set of print agent coverage vectors may be determined from the print agent coverage vectors characterising the skeleton using interpolation.

Abstract: Certain examples relate to a method of color prediction. Data indicative of color characteristics measured from a number of color test patches is obtained. Data indicative of combinations of color resources used to render the color test patches on a color rendering device is obtained. A first predictive model is trained using the data indicative of the combinations of color resources as an input and corresponding data indicative of color characteristics as ground truth outputs. A second predictive model is trained using the output data from the first predictive model as an input and the corresponding data indicative of color characteristics as ground truth outputs. A progressive mapping is implemented by the first and second predictive models to predict color characteristics rendered by the color rendering device given a combination of color resources.

Abstract: Certain examples described herein relate to a color processing apparatus and a method of generating configuration data for a color rendering device. The color rendering device operates based on color state instructions indicating output color states for portions of a rendered output. Render data may be generated by applying a halftone matrix and color data may indicate probability values for the output color states for input image areas corresponding to the portions of the rendered output. In described examples, configuration data defines an order of output color states for application of the halftone matrix. In the order, the output color states are grouped within the data based on color properties of a rendered output and an order within the clusters is based on colorant composition.

Abstract: 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.

Abstract: Disclosed is an apparatus generate updated sets of printing parameters for a printing process, the apparatus comprising a processor to receive initial correspondence data indicating correspondence between a plurality of color values and respective sets of printing parameters, wherein at least one colorant combination and a respective coefficient is assigned to each of the sets of printing parameters. The processor is to assign a weight to each colorant combination in the initial correspondence data based on at least a printing quality criterion relating to the colorant combinations within the initial correspondence data, and re-assign colorant combinations and respective coefficients to generate updated sets of printing parameters based on the assigned weights. Also disclosed is a method and a non-transitory computer readable storage medium.

Abstract: Certain examples described herein relate to adjusting a printing system. In certain cases, a lookup table, LUT, is obtained where the lookup table comprises a plurality of nodes that map a plurality of input first color space values to a plurality of Neugebauer Primary area coverage, NPac, vectors in a second color space and each NPac vector comprises at least one Neugebauer Primary, NP. Each NPac vector in the LUT is adjusted by the determination of a colorimetric value of the NPac vector and the modification of the NPac vector based on a characteristic of the corresponding at least one NP and the colorimetric value such that the modification is specific to the NPac vector. The lookup table is updated with the modified NPac vector and stored for referral by the printing system in any future printing.

Abstract: 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.

Abstract: Certain examples described herein relate to a color processing apparatus and a method of generating configuration data for a color rendering device. The color rendering device operates based on color state instructions indicating output color states for portions of a rendered output. Render data may be generated by applying a halftone matrix and color data may indicate probability values for the output color states for input image areas corresponding to the portions of the rendered output. In described examples, configuration data defines an order of output color states for application of the halftone matrix. In the order, the output color states are grouped within the data based on color properties of a rendered output and an order within the clusters is based on colorant composition.