Hp Indigo B.v.

Hewlett-packard Development Company, L.P.

Hewlett-packard Indigo B.v.

Ben-gurion University of the Negev Research and Development Authority

Oren Haik

Oded Perry

Tal Frank

Avi Malki

Noam Shaham

Ram Dagan

Omri Shacham

Dror Kella

Liron Itan

Tamar Kashti

Eli Velner

Yotam Ben-Shoshan

Smadar Shiffman

Zelidor Fineberg

Marina Limonov

Boaz Tagansky

Gregory Braverman

Mirta Perlman

Eli Chen

Mani Fischer

Gidi Amir

Alexander Spivakovsky

Yitzhak Yitzhaky

Tal Framk

Shay Bornstein

Liron Iton

David Savelzon

In an example, a method includes determining, using a processor, a first halftone screen comprising a plurality of cells. Each of the cells may contain a predetermined pixel cluster pattern, and a centre position of a cluster pattern within a first cell may be different to a centre position of a cluster pattern within a second cell.

Halftone screens comprising cluster patterns having different centre positions

A first separation distance is determined between a first pair of defects in a scanned image of a first printed sheet, and a second separation distance is determined between a second pair of defects in a scanned image of a second printed sheet. The defects are determined as having a separation distance in that the first and second separation distances are each within a first threshold of a specified separation distance and/or a difference between the first and second separation distances is below a second threshold. A source of the defects can be determined based on the characteristic separation distance.

Determining defects having a characteristic separation distance

Examples of the present disclosure relate to a method for skew detection in a printing system. The method comprises printing a document from an original digital image, scanning the document to produce a digital representation using an in line scanner of the printing system, and detecting skew in the digital representation independently from the original digital image.

Digital representation

In an example, an apparatus comprising an image processor is configured to perform edge detection on the image to detect a plurality of edges, automatically identify a path across the image based on the detected plurality of edges, divide the image into two adjacent sub-images based on the determined path, and generate first and second print data to cause the printing device to print the two adjacent sub-images.

Printing sub-images to create complete image

In some examples, a system selects a spanning region of an image spanning an intersection between adjacent sub-images that partition the image. The spanning region is divided based on a non-linear path that is determined on the basis of a user input, resulting in respective modified adjacent sub-images. Print data to cause a printing device to print the respective modified adjacent sub-images is generated on the basis of the dividing.

Dividing a spanning region of adjacent sub-images to generate print data

In one example of the disclosure, a set of scanned images is accessed. The scanned images are scans of distinct printouts of subject images produced utilizing an intermediate transfer member. A set of defect maps is created by comparing the scanned images to reference data for the subject images. The set of defect maps are combined into an integrated defect map. A dent defect on the ITM is identified utilizing the integrated defect map.

ITM dent identification utilizing integrated defect maps

A method for processing an image is disclosed. The method may include obtaining a target image to be printed using print agent in a printable area of a substrate of a particular colour. The method may include obtaining a scanned image of a substrate on which the target image has been printed, the substrate being of the particular colour. The method may include determining, from the scanned image, the particular colour of the substrate. The method may include using the target image as a reference image against which the scanned image is to be compared. The method may include adjusting a colour in the reference image according to the determined particular colour of the substrate. An apparatus and a machine-readable medium are also disclosed.

Adjusting a colour in an image

In an example, a method includes determining, by a processor, a cumulative indication of defects present in linear sub-portions located in a common position of each of a plurality of substrate sheets bearing a printed image. The method may further comprise identifying, by the processor, a linear defect based on the cumulative indication of defects.

Identifying linear defects

In an example, a method includes determining, by a processor, at least one separation distance between defects in a scanned image of a printed substrate sheet bearing a printed image, wherein the separation distance determined in a predetermined direction. The method may further comprise determining, by the processor, if the defects have a characteristic separation distance.

A method and apparatus for generating print data are described herein. An apparatus comprising an image processor () is configured to select a region of an image spanning an intersection between at least two adjacent sub-images that partition the image. The spanning region is divided based on a non-linear path that is determined on the basis of a user input, resulting in at least two modified adjacent sub-images. Print data operable to cause a printing device () to print the respective modified adjacent sub-images are generated on the basis of the dividing.

Examples analyze a digital image to determine an amount of high-frequencies corresponding to each pixel of the digital image based at least in part on gradients corresponding to a pixel neighborhood of each pixel. Examples analyze the digital image to determine a degree of randomness for each pixel based at least in part on the corresponding gradients. Examples generate an activity mask for the digital image based at least in part on the amount of high-frequencies and the degree of randomness corresponding to each pixel. Examples process the pixels of the digital image by performing gray component replacement to generate a color transformed image based at least in part on the activity mask.

Gray component replacement in a digital image to generate a color transformed image

In one example of the disclosure, a set of scanned images is accessed. The scanned images are scans of distinct printouts of subject images produced utilizing a photo imaging plate. A set of defect maps is created by comparing the scanned images to reference data for the subject images. The set of defect maps are combined into an integrated defect map. A scratch defect on the PIP is identified utilizing the integrated defect map.

Scratch identification utilizing integrated defect maps

An example system includes a color engine to separate an image into a plurality of color components. The system also includes a halftone engine to generate a plurality of halftone images based on the plurality of color components and a plurality of halftone screens. For each halftone screen, the halftone cell centers for that halftone screen occur at regular or semi-regular distances relative to a dot pitch. The plurality of halftone screens forms a high frequency moire pattern when the halftone screens are overlaid on each other. Each of the halftone screens have a granularity metric less than a threshold.

Halftone screens

Apparatus to detect a defect in a printed image and methods of detecting detects in a printed image are described. In some examples, a printing operation is initiated using image data to generate a printed image. The printed image is then scanned to generate a scanned image. A resolution of the scanned image is estimated, calculated or determined on the basis of a characteristic of the printing operation, and a reference image, having a resolution corresponding to the estimated, calculated or determined resolution, is generated from the image data. Whether defects are present in the printed image may be determined on the basis of a comparison of the reference image with the scanned image.

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Ness Ziona, Israel

Oren Haik