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: 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: In some examples, data representing a three-dimensional object is received. The data may comprise an object property description associated with each of a plurality of locations within the object. At least one object generation parameter description associated with a region of the object may be determined from the data. The object generation parameter description may comprise at least one object generation apparatus control parameter value and a probability that control data generated therefrom will specify said object generation apparatus control parameter value for generating the region of the object.

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: A method comprises obtaining at a processor a first color gamut and a second gamut represented in a first color space. The first and second gamuts are represented as first and second objects in a second color space, with each object comprising a plurality of nodes. For each node, an index is provided indicating a position in the first color space to which that node corresponds. A further index is provided indicating a position, in the first color space, of the node relative to at least one other node of the object to which the node belongs. Each node of the first object corresponds with a node of the second object providing a mapping between the objects, using the further index. The index of at least one of the first object nodes is adjusted based on the corresponding node of the second object producing a mapping between the gamuts.

Abstract: A method is described in which a reflection is obtained of a laser light pattern reflected from a substrate. A reflection of diffuse light may be obtained from the substrate. A first parameter may be determined, relating to the substrate from the reflected laser light pattern. A second parameter may be determined, relating to the substrate from the reflected diffuse light and a characteristic of the substrate may be determined from the first and second parameters. A print apparatus and a machine-readable medium are also disclosed.

Abstract: Example methods and systems are described in which a color space vector is transformed into a Neugebauer primary area coverage (NPac) vector, to be used for printing. In some examples, the color space vector is transformed into a NPac vector on the basis of criteria associated to amounts or probabilities of Neugebauer primaries (NPs).

Abstract: Certain examples described herein relate to smoothing a lookup table for an imaging system. The lookup table comprises entries to map elements in a first color space to corresponding elements in a second color space. In certain cases, the entries of the lookup table are classified into a plurality of classes, each of the plurality of classes being based on a color space characteristic in the first color space or the second color space. Each of the plurality of classes of entries is sequentially smoothed.

Abstract: Certain examples relate to the processing of spot colors within a printing pipeline. In these example, a palette of spot colors indicated in a print job is determined. The palette is mapped to a set of vectors in a colorant-dependent color space based on a comparison of target spectral characteristics for the spot colors and measured spectral characteristics of the printing system. The set of vectors is used to assign vectors to print-resolution areas of the print job before halftoning.

Abstract: Apparatus and methods for transforming three dimensional object data are disclosed. In some examples, data representing a three dimensional object is received, the data comprising object property data indicative of at least one attribute of at least a portion of the three dimensional object. The object property data is transformed into a plurality of device independent object property data objects having a common data structure, each object property data object comprising a value indicative of each of a predetermined set of object properties.

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: In an example, a method includes receiving, at a processor, a first matrix comprising a set of print coverage vectors, each print coverage vector specifying print materials for object generation using additive manufacturing and a second matrix comprising a corresponding set of properties for objects generated using the print coverage vectors. The method may further include determining, by the processor, a solution to an objective function relating the first and second matrices.

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: 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: 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: In an example, a method includes receiving, at a processor, a plurality of property parameter sets representing attainable property combinations in additive manufacturing and being associated with print material description. A constraint of a first property of the property parameter sets may also be received and a hull of a property mapping resource for use in determining additive manufacturing instructions for generating an object in which the first property meets the received constraint may be determined.

Abstract: Certain examples described herein relate to generating a Neugebauer Primary area coverage (NPac) vector. In certain cases, an operating state of a printing system is determined. A first NPac vector is obtained, having an initial set of Neugebauer Primaries (NPs). The initial set of NPs comprise a NP that is not implementable with the operating state. A target set of NPs is determined on the basis of the operating state, the target set of NPs being implementable with the operating state. A second NPac vector is generated, the second NPac vector having the target set of NPs.