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: 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: 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 receiving, at at least one processor, object model data representing at least a portion of an object that is to be generated by an additive manufacturing apparatus by fusing build material within a fabrication chamber. An intended object placement location within the fabrication chamber may be determined, and a dimensional compensation to apply to the object model data may be determined using a mapping resource relating dimensional compensations to object placement locations. The determined dimensional compensation may be applied to the object model data to generate modified object model data using at least one processor.