Hewlett-packard Development Company, L.P.

Ben-gurion University of the Negev Research and Development Authority

Hewlett-packard Indigo B.v.

Omri Shacham

Oren Haik

Mani Fischer

Jan Philip Allebach

Carl Staelin

Tamar Kashti

Doron Shaked

Madhur Gupta

Puneet Goyal

Dror Kella

Oded Perry

Gidi Amir

Smadar Shiffman

Jin-young Kim

Yitzhak Yitzhaky

Yung-Yao Chen

David Savelzon

Adi Grossman

A method includes obtaining an image of a document against a background. A bounding box that bounds a region of the image that is distinguishable from the background is found. Coordinates of a plurality of points of the distinguishable region are found, each point being a point of the distinguishable region that is closest to each corner of the bounding box. The document is identified within the image as a region of the image whose corners are defined by the found coordinates.

Automatic detection of corners of an imaged document

Printing with a single colorant a security feature imperceptible to the naked eye. For a digital security image having a first region formed by a first pattern of binary pixels and a second region formed by a different second pattern of binary pixels, the first and second patterns are printed with the single colorant. A darker one of the first and second printed patterns is determined. The security image is printed with the single colorant, the region corresponding to the darker printed pattern printed at a reduced gray level such that the printed first and second regions appear substantially indistinguishable to the naked eye.

Security image printing

A method for generating a clustered halftone representation of a continuous-tone image for printing includes applying a search technique. In the search technique, evaluation of a similarity between an initial halftone and the continuous-tone image includes application of an initialization filter to an initial error image that represents a difference between the initial halftone and the continuous-tone image. Evaluation of a similarity between each updated halftone, formed by modifying a previously-evaluated halftone, and the continuous-tone image includes application of an update filter that is different from the initialization filter to an updated error image that represents a difference between the updated halftone and the continuous-tone image. Relating computer program product and data processing system are also disclosed.

Clustered halftone generation

A method for predicting an appearance of a rendering by a printer of a digital halftone representation of a continuous-tone image includes calculating a predicted absorptance value of a dot of a rendered halftone of the digital halftone representation. The dot corresponds to a pixel of the digital halftone representation. The predicted absorptance value is based on a configuration of pixel values of pixels in an immediate neighborhood of the pixel, and on a weighted contribution of a pixel value of each pixel in an outer neighborhood of the pixel. The method may be incorporated into a halftoning technique. Relating computer program product and data processing system are also disclosed.

Method and system for enhancing a digital halftone representation for printing

A system and method for cache hit management.

Cache hit management

A method for designing a screen set for color halftoning includes selecting a screen set that includes at least two screens. The screens are applied to a uniform color image so as to form a set of corresponding colorant halftones. The colorant halftones are superposed to form a color halftone. A spatial frequency spectrum of the color halftone is calculated. Maxima of the spatial frequency spectrum that occur at two effective frequencies are identified, the two effective frequencies being located in two adjacent quadrants of a complex spatial frequency space. A magnitude of each effective frequency is compared with a predetermined frequency magnitude. The screen set is accepted for future application for color halftoning only if both effective frequency magnitudes are greater than the predetermined frequency magnitude. Relating computer program product and data processing system are also disclosed.

Color screen sets

A set of screens is provided for use in printing respective color separations in a halftone color printing process. This set of screens comprises at least two clustered-dot screens and the frequency and angle parameter values of the screens is such that the lowest frequency moir&#xe9; produced by any combination of at least two frequency components, taken from the group comprising the first and second screen harmonics, for which the sum of the harmonic orders of the frequency components in the combination is less than a predetermined value, is of a sufficiently high frequency as to be substantially unperceivable to the human visual system; other moir&#xe9;s are also substantially unperceivable to the human visual system. The lowest frequency moir&#xe9; serves to reduce the visibility of color changes caused by color plane registration variations. A printing system and method employing the screen set are also provided.

Reducing the visibility of color changes caused by color plane registration variations in halftone color printing

A system and a method for automatic restoration of isotropic degradations of a digital image, based on receiving a blurred image by an image capture assembly, automatically finding proper step edge, calculating the PSF from the step edge, and restoring the blurred image by means of a processor, and with the option to display the resorted image by means of an output assembly.

Growing community of inventors

Mitzpe Ramon, Israel

Omri Shacham