Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Certain examples described herein relate to a method in which a model for predicting a characteristic of a printed halftone image is generated. The method may include receiving sets of image data, each representing a respective image. The sets of image data may include input image data representing the respective image using a halftone pattern, and corresponding printed image data representing a printed version of the respective image printed on the basis of the halftone pattern. A training process may be iteratively performed to train a neural network to generate a mapping between input image data and printed image data. The model may be generated on the basis of the mapping. An apparatus, a system and a non-transitory computer-readable storage medium are also described.

Abstract: A method comprises forming a halftone screen set comprising first, second and third halftone screens. A first regular halftone screen for the screen set is selected. A second regular halftone screen is determined, using a processor, by performing a regularity invariant transformation on the first regular halftone screen. A third halftone screen is determined based on at least one predetermined condition being satisfied between the first, second and third halftone screens.

Abstract: 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.

Abstract: A method is disclosed. The method may comprise obtaining first image data representing a reference image to be printed on a substrate. The method may comprise obtaining second image data representing a scanned image of a substrate on which the reference image has been printed. The method may comprise combining the first image data and the second image data to generate combined image data. The method may comprise providing the combined image data as an input to a classifier component to identify a difference between the first image data and the second image data. An apparatus and a machine-readable medium are also disclosed.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method and apparatus for generating print data are described herein. An apparatus comprising an image processor (110) 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 (150) to print the respective modified adjacent sub-images are generated on the basis of the dividing.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A method is described in which an image is received, the image including a document and background area; a candidate location of a boundary between the document and the background area is found; and a validity of the candidate location of the boundary is checked, based on pixel values around the candidate location of a first channel of the image, and pixel values around the candidate location of at least one other channel of the image, wherein the at least one other channel is different from the first channel.