Abstract: A method and apparatus is used for preserving a black channel when a reference color space without a black channel is used to convert between a source black channel color space and a destination black channel color space. In one embodiment, the preservation and conversion system receives an image represented in a black channel color space and converts it to a reference color space, correlates at least one channel from the reference color space with a black output level that identifies a look-up table (LUT) for color values and a weight for interpolating the color values in the LUT for a destination device, interpolates between color values in at least two LUTs using the weight, and converts the image in the reference color space to the destination the black channel color space using the black output level and interpolated color values in the LUT.

Abstract: In one embodiment, a print system includes an anticipated ambient lighting selector to allow selection of an anticipated ambient lighting. A rendering module is configured to map a print job into raster data configured to reduce color cast in gray output when displayed under the anticipated ambient lighting.

Abstract: The final-hardcopy operating facility, “target facility”, converts the content provider's original data file to a different color space to form a proofing data file. A proofing facility, which is distinct from the target facility, uses the proofing file to produce a visible proof for viewing by the content provider, customer etc. A common proofing file is applied to both preparing the proof and printing the final hardcopy. Because it is the target facility rather than the content provider or the proofing facility that prepares the proofing file, using maximum available knowledge about the printing equipment which will be used and its color characterization and other technical behavior, this approach gives maximum assurance that the final hardcopy will represent the proof as accurately as practical.

Abstract: A direct device-space-to-device-space transform adjusts the amount of actual black ink, to avoid highlight and midtone granularity in incremental printing—but with no need for translation into perceptual space. If the amount of black ink specified in the input data for a particular color is very small or very large, then that specified color is passed through the transform without substantial change. Thereby the amount of actual black ink and other colorants is held as nearly as practical at levels dictated by device-space input specifications while minimizing visible granularity. Replacement behavior is chosen to smoothly blend between different kinds of operation in different tonal ranges. This system accommodates personnel trained in classical printing-press technologies, who are accustomed to full control over amounts of black and other colorants.

Abstract: To compensate for color-calibration sensor drift, a measurement of bare-print-medium tonal value is taken in immediate time juxtaposition to each color test pattern; measured bare-medium tone is then used to correct color-patch readings. A line sensor or the like, on the scanning printhead carriage, is used for the reading. Preferably two such readings are taken, one at each end of each test pattern; ideally separate scans of the bare medium are taken without any test-pattern patch to develop longterm and short-term drift profiles, for refining the corrections. To compensate for calibration error due to runout in the carriage track—particularly for wide-bed printers—sensor response to bare medium is used to represent variations in carriage-to-medium spacing along the track; these variations are corrected in later sensor use.

Abstract: The final-hardcopy operating facility, “target facility”, converts the content provider's original data file to a different color space to form a proofing data file. A proofing facility, which is distinct from the target facility, uses the proofing file to produce a visible proof for viewing by the content provider, customer etc. A common proofing file is applied to both preparing the proof and printing the final hardcopy. Because it is the target facility rather than the content provider or the proofing facility that prepares the proofing file, using maximum available knowledge about the printing equipment which will be used and its color characterization and other technical behavior, this approach gives maximum assurance that the final hardcopy will represent the proof as accurately as practical.

Abstract: There is disclosed a method of dynamic generation of a linearized halftone matrix from a high bit resolution halftone matrix, for use in a printer device, for example a domestic or office printer device or a commercial high resolution printer device. A high bit resolution halftone threshold matrix is converted into a vector format (700). A tone correction function is applied by selecting a variable number of index values, each index value representing a threshold level. A tone corrected two-dimensional 8 bit threshold level matrix, is then applied to a corresponding print image plane comprising a plurality of pixels to obtain a two dimensional print data for each of a plurality of colors of an image. The print data is printed as a plurality of dots by a print head to form a printed image using a halftoning method.