Abstract: Methods and apparatus for three-dimensional object representation are described. In an example, data representing a three-dimensional object is received, the data comprising an object property description associated with each of a plurality of locations within the object. Distinct object property descriptions are identified and a data object, which has a plurality of addresses, is populated with data indicative of the distinct object property descriptions, such that data indicative of each distinct object property description is represented at a different address. Data comprising a representation of the object is generated, the data comprising a data object address associated with each of a plurality of locations, wherein the data object address corresponds to the address of data indicative of the object property description for that location.

Abstract: In an example, a method includes determining a plurality of print coverage vectors, each of the print coverage vectors specifying a common amount of a selected print agent. The method may further comprise determining a colorimetry provided by each of the print coverage vectors and dividing a range of colorimetries into partitions in a colorimetric space. For each of a plurality of the partitions, the method may include determining a characteristic of each print coverage vector resulting in a colorimetry within that partition and selecting a print coverage vector for that partition based on the determination. A color mapping resource may be determined based on the selected print coverage vectors.

Abstract: A method of processing data in a multi-stage imaging pipeline, the method comprising, at each stage of the multi-stage imaging pipeline, identifying a plurality of encoding values represented in received input data in a given encoding space for the respective pipeline stage, the identified plurality of encoding values comprising a subset of encoded values which are capable of being represented in the given encoding space, generating a list of encoding indices corresponding to the identified plurality of encoded values in the given encoding space, representing the encodings of one or more entities of the received input data using the generated list of encoding indices, and outputting the represented encodings of the one or more entities to the next stage of the multi-stage imaging pipeline.

Abstract: An example method of linearizing print outputs for a printing system is described. The method involves retrieving a look-up table comprising a plurality of nodes that map input space values to Neugebauer Primary Area Coverage vectors. The printing system is used to print a set of ramps, each ramp comprising a plurality of test areas. The test areas for each ramp are defined by varying vector element values corresponding to input space values that vary in a dimension of the input space. A property of each of the printed test areas is measured and a linearization function is determined based on those measured properties. The linearization function is then applied to the input space values for the plurality of nodes in the look-up table.

Abstract: A method of calibrating an area coverage representation of a color. A first area coverage of a Neugebauer primary in an area coverage representation of a color is determined based on a plurality of reference area coverage parameters for the Neugebauer primary, wherein each reference area coverage parameter in the plurality of reference area coverage parameters corresponds to a respective colorant deposition subsystem in a plurality of colorant deposition subsystems. A second area coverage of the Neugebauer primary is determined based on the plurality of reference area coverage parameters and a plurality of calibration parameters for the Neugebauer primary, wherein each calibration parameter in the plurality of calibration parameters corresponds to a respective colorant deposition subsystem in the plurality of colorant deposition subsystems.

Abstract: Example methods of controlling printing of a halftone image are disclosed as well as apparatuses and computer-readable storage mediums relating thereto. In an example, the method includes receiving input data indicating a first colorant deposition order for a colorant combination and a second colorant deposition order for the colorant combination, wherein the second colorant deposition order is different from the first colorant deposition order. Control data is generated based on the input data. The control data includes first pixel data associating a first pixel in the halftone image with the first colorant deposition order, and second pixel data associating a second pixel in the halftone image with the second colorant deposition order. The control data is used to control a printer to print the halftone. The above amendments are reflected in the attached substitute specification shown in clean and marked-up form in the Appendix submitted herewith.

Abstract: In an example, an image processing system may include an identification engine, a map engine, and a control engine. In that example, the identification engine may identify a color mapping resource in response to a classification identifier corresponding to image data, the map engine may map the image data with the color mapping resource having color space clause corresponding to the classification identifier, and the control engine may generate control data for operating a print apparatus to print based on the color mapping resource.

Abstract: A look-up table for use in a printing system is created. The printing system prints an input image in a print color space. The look-up table is created by accessing a predetermined look-up table representing a mapping of color values of an input color space to ink-vectors of a print color space; applying a p-by-q halftone threshold matrix to each ink-vector of the predetermined look-up table to generate a p-by-q halftone cell for each ink-vector; and creating a further look-up table which maps, at least a sample of, the color values of input color space to the at least one halftone cell.

Abstract: Defining color separation for printing an image is disclosed. A color separation model is created. The model comprises a separation hypercube, wherein each axis of the separation hypercube represents a metric of the printing process and each vertex of the separation hypercube at each end of each axis represents the optimized separation of each metric. A weighting for at least one of the metrics represented by the created color separation model is determined. The determined weighting is applied to each of the vertices of the created color separation model to determine new vertices. A new color separation model based on the determined new vertices is created.

Abstract: A system includes a memory to store ink-channel data that describe print resources for an ink-channel printing pipeline and Neugebauer Primary area coverage (NPac) data of an alternative printing pipeline. An NPac property stored in the memory describes a dimensional relationship between the NPac data of the alternative printing pipeline and the ink-channel data for the ink-channel printing pipeline. The system includes a processor to execute instructions stored in the memory. The instructions generate a mapping file based on the NPac property to map from an ink-channel space described by the ink-channel data to an NPac space described by the NPac data.

Abstract: Certain examples described herein relate to structure forming for the production of a three-dimensional object. In these examples, different structure forming components or functions are applied to volumes of a three-dimensional object. These structure forming components or functions are arranged to differentially generate a halftone output. The halftone output is generated by processing a material volume coverage representation for the three-dimensional object. The halftone output is used to provide control data for instructing production of a three-dimensional object.

Abstract: In some examples, a method for compressing a spectral reflectance dataset may be performed through compression circuitry. The method may include computing a principal component analysis basis for the spectral reflectance dataset; projecting the spectral reflectance dataset onto the principal component analysis basis to obtain a weight matrix; quantizing the weight matrix; performing a Huffman encoding process on the quantized weight matrix to generate a Huffman table and Huffman codes for the quantized weight matrix; and providing compressed spectral reflectance data as the principal component analysis basis, the Huffman table, and the Huffman codes.

Abstract: In an example, a method includes characterising, using at least one computer, an initial gamut from an initial set of color mappings from a source color space to a printing device color space. The method may further include characterising, using at least one computer, an initial gamut from an initial set of color mappings from a source color space to a printing device color space. The method may further include characterising, using the at least one computer, a printing device color gamut. The method may further include transforming, using the at least one computer, the initial set of color mappings to form a transformed set of color mappings mapping from the source color space to the printing device color gamut.

Abstract: A color image is processed into a renderable image. The color image comprises a plurality of pixels. Each pixel has colorimetry defined in a first color space. The renderable image comprises a plurality of renderable pixels defined by a device-vector in a second color space. For each pixel: a device-vector defined in the second color space is selected (301) based on the colorimetry defined in a first color space of the pixel. The device-vector comprises a plurality of elements. Each element includes an identifier and an accumulated weighting. An element of the selected device-vector is reselected (303) until the accumulated weighting (a) is greater than a threshold value (t) associated with the pixel (305). The levels for each color of the second color space (or mappings) for the currently selected (307) element of the selected device-vector is determined (309) to convert the pixel into a renderable pixel.

Abstract: Methods and apparatus relating to substructures for three-dimensional objects are described. In an example, a processing apparatus includes: an interface to receive data representing a three-dimensional model object, the data including object model data and object property data; a mapping module to map received data to a print material coverage representation; a halftone module to provide halftone threshold data; and a substructure module to define a substructure for a three-dimensional object to be generated, the substructure specifying in at least a region thereof a consistent lattice structure and a variable material distribution. The apparatus is to apply a substructure and a halftoning to the print material coverage representation to generate control data for the production of a three-dimensional object having the substructure.

Abstract: Certain examples described herein relate to apparatus arranged to produce a three-dimensional object. These examples enable color and material properties of such an apparatus to be characterized. This is achieved through the generation of configuration data for the apparatus that maps at least one color property to one or more material volume coverage vector values. This allows for appropriate quantities of materials available to the apparatus to be used to produce colors defined in received object data for the three-dimensional object.

Abstract: Methods and apparatus relating to substructures for 3D objects are described. In an example, a method for providing a three-dimensional halftone threshold matrix is described. The method may comprise receiving a substructure model representing a three-dimensional material structure and populating each location in the substructure model at which the structure exists with a halftone threshold value.

Abstract: Certain examples described herein relate to color calibration. In certain cases, a plurality of test patches are printed with a printing system, the test patches corresponding to a set of initial color sample points and a set of test colors. Color properties of the printed test patches are measured. In certain examples, a gamut descriptor is identified from a plurality of gamut descriptors using the color properties of the test colors. Each gamut descriptor defines a set of up-sampling parameters for a particular color gamut. Measured color properties for the initial color sample points are up-sampled using the set of up-sampling parameters for the identified gamut descriptor to generate up-sampled data. In certain cases, the up-sampled data is used to generate a color mapping to be applied to print job data received by the printing system.

Abstract: Methods and apparatus relating to three-dimensional object models are described. In one example, (i) data representing a geometrical description of a three-dimensional object defining object geometry in a geometric space and (ii) at least one object property description describing an object property in an object property space are received. The object property space and the geometric space are intersected to define an object model, wherein an object property is defined at an intersection between a described object property and defined object geometry.

Abstract: A method for processing an object for printing, the object comprising a plurality of properties defined at each of a plurality of locations within the object, each property represented by a metamer set of possible combinations of proportions of at least one of a set of printing materials, the method comprising: selecting a combination of the metamer sets of a given location within an object that provides all of the plurality of properties defined for the given location.