A method and a system for image compression are disclosed. An image is converted to a halftoned image. The one or more halftoned lines in the halftoned image comprise one or more pixels. A first transformed image is generated from the halftoned image based on shifting of the one or more pixels, associated with the one or more halftoned lines in the halftoned image, by a first value. A second transformed image is generated from the first transformed image based on shifting of the one or more pixels, associated with the one or more halftoned lines in the first transformed image, by a second value. Further, a compressed image is generated based on compression of the second transformed image. The compressed image is stored in a storage device. Another method and system for image conversion are disclosed that converts the compressed image back to the first transformed image.

A printing device for providing multiple documents of one type includes a data receiving portion for receiving an image data, a processor, and a printing module. The processor is used to process the image data to generate a first printing information and a second printing information. The printing module is used to print a first document and a second document according to the first and second printing information, respectively. The first printing information includes the image data and a first identifying information, and the second printing information includes the image data and a second identifying information different from the first identifying information. The first identifying information is composed of a first set of halftone pattern, a first set of lines or a combining information thereof. The second identifying information is composed of a second set of halftone pattern, a second set of lines or a combining information thereof.

A method of forming a halftone screen, the method comprising: representing a first tone range by forming a plurality of dots arranged in a grid; representing a second tone range by forming a plurality of substantially cross-shaped dots arranged in a grid, the cross-shaped dots contained within respective dot cells and having four arms, a distal end of at least one of the arms wider than a proximal end, the second tone range darker than the first tone range; and representing a third tone range by forming a plurality of substantially cross-shaped dots arranged in a grid, the cross-shaped dots contained within respective dot cells and having four arms, a proximal end of at least one of the arms wider than the proximal end of at least one arm of the cross-shaped dots representing the second tone range, the third tone range darker than the second tone range.

A computational halftoning process determines a halftoned image having halftoned pixel values by processing an array of input pixels. For each input pixel, an array of high-resolution printer coordinates is defined at a higher spatial resolution than the printer resolution, and a coordinate transformation is applied to determine a corresponding array of high-resolution dot coordinates. An array of high-resolution halftoned pixel values is then determined responsive to the code value of the input pixel by addressing a halftone dot function using the array of high-resolution dot coordinates. A halftoned pixel value is then determined by averaging the high-resolution halftoned pixel values.

A print control apparatus is configured to control a print head adapted to discharge ink droplets of a plurality of sizes to execute printing. The print control apparatus includes a print control unit configured to acquire a gradation value of an ink color based on image data and to determine whether or not to discharge an ink droplet of one of the plurality of sizes based on the gradation value. The print control unit is configured to determine that the ink droplet to be discharged is the ink droplet of a first size or smaller when the gradation value belongs to a maximum value-side partial range including a maximum value, and to determine that the ink droplet to be discharged is only the ink droplet of the first size when the gradation value belongs to a range towards a minimum value-side than the partial range.

A method for imaging a mask layer includes providing a mask layer, receiving an image file and detecting at least one solid area and at least one halftone area in the image file, imaging an area of the mask layer corresponding to the at least one solid area, using a first imaging setting, wherein prior to or during the imaging a sampling pattern is superimposed on pixels of the at least one solid area, so that only a portion of the pixels of the at least one solid area is imaged, and imaging an area of the mask layer corresponding to said at least one halftone area, using a second imaging setting which is different from the first imaging setting.

A determination method includes outputting a pattern image including a first region where a halftone image is formed and a second region where another halftone image is formed, the halftone image of the second region being constituted by dots of an average dot size smaller than an average dot size of dots constituting the halftone image of the first region, comparing a density of the first region with a density of the second region in the pattern image output on the recording material, and determining that the plurality of kinds of toner are mixed within the toner storage portion in a case where a visual density of the halftone image of the first region is higher than a visual density of the second region.

A printing device acquires a position of a missing dot in which, despite a position where a dot is to be formed, the dot cannot be formed by the head, performs halftone processing of generating dot data indicating whether to form a dot, using image data including a plurality of pixels having a plurality of tone values and a dither mask including a plurality of thresholds, searches for a threshold used in generation of a dot in a range near the missing dot, modifies a value of a change threshold, which is a threshold satisfying a search condition of being higher than a value of a target threshold, which is a threshold used at the position of the missing dot, to a value equivalent to the value of the target threshold, and provides the modified threshold for the halftone processing at the pixel corresponding to the modified threshold.

A method of generating dot data representing positions of dots formed of ink from a print head includes a first detection step of detecting, as a first processing target edge portion, at least one of a first edge portion located at one side in a first direction in an area darker than a surrounding area and a second edge portion located at one side in a second direction crossing the first direction in an area darker than a surrounding area out of edges existing in a detection target area in at least a part of an image having a plurality of pixels arranged in the first direction and the second direction, and a generation step of generating the dot data from the image such that an amount of the ink ejected from the print head to the first processing target edge portion is reduced.