Hewlett-packard Development Company, L.p.

Johan Maurice Lammens

Michel Georges Encrenaz

Jan Morovic

Peter Morovic

Jacint Humet Pous

Juan Uroz

Yvan Richard

William James Allen

Jordi Arnabat Benedicto

Francesc Subirada

David Herbert Donovan

Miquel Boleda

Rodolfo Jodra

Miguel Angel Lopez

Pau Soler

Jordi Vilar

Francesco Subirada

Described herein are systems and methods for processing an image such as a halftone image. For example, in some embodiments, pixels of an image are checked to see if when printed would be represented by a given output. Pixels of the image that match defined values are replaced with pixels that are represented by a different set of outputs. This latter set of outputs may be selected to optimize one or more imaging attributes.

Pixel processing

Scanner, method or computer program product, arranged to sense media color information, store predetermined color values of preselected non-printed media and storing corresponding color profiles adapted for the respective preselected media, and process sensed color values, compare a sensed color value with the predetermined color values, and select one of said color profiles based on the comparison.

Color profile selection

Method of computing a convex hull in a predetermined color space, comprising determining a print attribute value range pertaining to a reference print attribute value, selecting base NP (Neugebauer Primary) area coverages, comprising area coverages of single NPs and combined NPs, having print attribute values in the print attribute value range, printing and measuring patches corresponding to the base NP area coverages, computing linear combinations of the base NP area coverages, and assigning one of the base NP area coverage or the linear combination of base NP area coverages to the corresponding color, depending on which is closest to the reference print attribute value.

Printing system

A method of printing using variable pixel replication factors involves generating from an input image a reference image and a plurality of half-tone source images generated at different resolutions of the input image and with post-halftoning pixel replication factors applied such that the half-tone source images are all the same size. A pixel-replication factor selector function is applied to each reference pixel of the reference image to determine a respective source image for that reference pixel. Thus, different reference pixels correspond to different pixel replication factors. A print-state image is assembled by applying to each print-state image pixel the print state of the corresponding source pixel in the corresponding source image. The print-state image is then printed to a print medium.

Printing using variable pixel-replication factors

The disclosure describes methods for color printing, performing a color separation process and performing a halftoning process. Furthermore, the disclosure describes the color separation process determining one or more Neugebauer Primaries, tessellating the Neugebauer Primaries, and generating one or more Neugebauer Primary area coverage vectors, whose area coverages are linear with respect to a device-independent color space. The disclosure further describes that the color separation process communicates with the halftoning process using one or more Neugebauer Primary area coverage vectors.

Color separation into Neugebauer primary area coverage vectors

A print control system adapted to control a digital printer having a first machine-readable ink of a first colour and a second ink that is not machine readable at the same wavelength as said first ink and that is of substantially the same colour, said system being adapted to control said printer to print upon a document in said first ink a position&#x2014;determining pattern readable by a digital pen to enable said pen to acquire data to enable a position of said pen in said pattern to be determined, and to print human discernable content that is not read by said pen superposed with said pattern using said second ink and not said first ink.

Methods, apparatus and software for printing location pattern and printed materials

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.

Color cast reduction system and method

CDE is measured for each nozzle array, to enable modification of a mapping between input image data and intended printing marks to compensate for the CDE. Printing proceeds using the modified mapping, which is either an optical-density transformation of data to printing marks or a spatial-resolution relation between image data and intended pixel grid. The density transformation preferably includes a dither mask (but can be error-diffusion thresholding instead); the resolution relation includes scaling of image data to pixel grid. For some invention forms, CDE includes printing-density defects, measured and used to derive a correction pattern&#x2014;in turn used to modify halftone thresholding. For other forms CDE includes swath-height error, but still this is measured and used to derive a correction pattern etc. For still other forms, however, CDE includes swath-height error and correction takes the form of scaling. When the halftoning forms are applied to plural-pass printing, a printmask is used to map the dither mask etc. to the nozzle array, enabling application of the correction to the mask. Halftone forms ideally uses a gamma function, though threshold or linear corrections are possible instead. Halftone correction is effective in single-pass printing. The swath-height correction can modify heights of all nozzle arrays. Computations are done at most only once for a full image.

Apparatus and method for mitigating colorant-deposition errors in incremental printing

A method of applying a gray neutrality calibration to a color signal, said method comprising: representing said color signal as a position in a multi dimensional color space, in which each said dimension of said color space represents a respective primary color; defining a gray axis in said multi dimensional color space as a set of coordinates for which a plurality of said primary colors each have a same value as each other; determining a distance between said position representing said color signal and said gray axis; and using said determined distance between said color signal position and said gray axis to apply a gray neutrality correction to said input color signal.

4-dimensional gray neutrality calibration

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 (). 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.

Dynamic generation of linearized halftone matrix

A direct device-space-to-device-space transform adjusts the amount of actual black ink, to avoid highlight and midtone granularity in incremental printing&#x2014;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.

All-device-space automatic black replacement

A printing system is linearized automatically using measurements made with a simple optical sensor, such as a line sensor, that is onboard the system. The printing system itself is for forming images on plural printing media. Because the optical sensor is not a calorimeter or even a true densitometer, the sensor requires calibration, preferably based upon measurements using real inks. In the past it has been considered a requirement that such calibration be performed separately using each of the print media that was to be used for printing images. Linearization according to the invention, however, refers to a single calibration of the sensor, that calibration being used in common for essentially all media&#x2014;even though the single calibration is performed with respect to exclusively a single one of the plural media.

Linearization of an incremental printer by measurements referred to a media-independent sensor calibration

The final-hardcopy operating facility, &ldquo;target facility&rdquo;, 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.

Growing community of inventors

Sant Cugat del Valles, Spain

Johan Maurice Lammens