Abstract: A printing system is disclosed. The printing system includes a print engine including two or more print heads to generate an alignment chart and an alignment system. The alignment system receives the alignment chart and computes a magnitude of misalignment between the print heads.

Abstract: The systems and methods presented herein provide for calibrating a print engine of a printing system. The printing system prints image data on a print medium and scans the printed image data. Color values of the scanned image data are then measured and various tints of color values and their transition locations are identified. A calibration module estimates the original optical densities of the identified color value tints and generates a target optical density for each of the identified color value tints using the estimated original optical densities to determine print irregularities in the color values of the scanned image data. The calibration module then generates a halftone screen based on the mean optical densities and applies the generated halftone screen to the print engine to calibrate the print engine.

Abstract: Non integer scaling of images to reduce artifacts is presented herein. One embodiment includes determining a scaling resolution based on a pixel resolution of the image and a pixel resolution of an output device (i.e., factors of the scaling resolution). The image is converted to the scaling resolution to change (e.g., increase) the pixels of the image by the first factor. A grid is generated to scale the converted image. The grid has a number of sections defined according to the second factor times the pixel resolution of an output device. The converted image is sectioned according to the grid. Each section of the grid includes an integer number of pixels of the converted image. The color values of the pixels of the converted image are averaged within each section of the grid to compute a single color value for each section of the grid and scale the image.

Abstract: A printing system is disclosed. The printing system includes a halftone calibration system that receives one or more un-calibrated halftones, generates one or more calibrated halftones using an ink model from the one or more un-calibrated halftones, analyzes a printed calibration screen of the one or more calibrated halftones, and performs a halftone calibration.

Abstract: A method is disclosed. The method includes generating a seed pattern which ensures one dot per column, computing an auto correlation function and performing pixel error processing. Pixel error processing includes performing multiple operations during each iteration to create visually pleasing halftone mask patterns which follow a one dot per column constraint.

Abstract: Methods and systems herein provide for calibration of a production printing system that accommodates a plurality of different print paper types, including new paper types with no ICC profiles or optical density curves on file. One exemplary method includes printing test patches of primary colors on a first print medium, measuring colors of the test patches printed on the first print medium to determine an optical density of the first print medium, and comparing the optical density of the first print medium to a plurality of optical density curves to identify a comparable optical density curve of a different print medium. The comparable optical density curve is one of a plurality of optical density curves installed on the production printing system. The method further includes automatically selecting the comparable optical density curve to calibrate the production printing system to the different print medium for use in printing to the first print medium.

Abstract: Methods and apparatus herein provide for automated calibration of multiple printheads used in a multi-pass printing system. Aspects hereof print a plurality of gray scale printed patterns each printed pattern corresponding to a gray scale value for each of the multiple printheads. The printed patterns are then measured to determine the intensity (e.g., optical density) of each of the printed patterns. A measurement function is derived from the measured intensity and gray scale levels used to print each pattern. Calibrated transfer functions are then determined from the measurement function and target function where each calibrated transfer function relates, for a corresponding printhead, an input gray scale level of a pixel in an image to be printed to a calibrated gray scale level to use for the corresponding printhead when operating in multi-pass mode.

Abstract: Methods and systems herein provide for reducing artifacts during printing. One printing system is operable to prepare a continuous tone image (CTI) for printing onto a print medium by generating an initial half tone image (HTI) based on the CTI. The printing system includes a printer and a print controller. The print controller filters the initial HTI and the CTI with a perceptual filter and determines an error between the filtered CTI and the filtered HTI. The print controller prints the HTI via the printer to determine printer artifacts and processes a scanned version of the printed HTI to determine an error between the filtered CTI and the scanned and filtered HTI. This processing updates the initial HTI and reduces the error between the filtered CTI and the filtered HTI.

Abstract: Methods and systems herein provide for print data compensation for a print head based on a lateral offset of a media relative to the print head. In one embodiment, a print controller of a printer identifies an edge of a media that is parallel to a direction of travel of the media, and determines a lateral offset between the edge of the media and a print head of the printer. The print controller then modifies data for the print head based on the lateral offset to compensate for a lateral motion of the media relative to the print head.

Abstract: The systems and methods presented herein provide for calibrating a print engine of a printing system. The printing system prints image data on a print medium and scans the printed image data. Color values of the scanned image data are then measured and various tints of color values and their transition locations are identified. A calibration module estimates the original optical densities of the identified color value tints and generates a target optical density for each of the identified color value tints using the estimated original optical densities to determine print irregularities in the color values of the scanned image data. The calibration module then generates a halftone screen based on the mean optical densities and applies the generated halftone screen to the print engine to calibrate the print engine.

Abstract: Systems and associated methods provide for rewriteable lithographic printing. More specifically, imaging on a printing plate may be erased and the printing plate reimaged for subsequent printing. The printing plate includes a surface coated with a photoswitchable film. An ultraviolet light source is operable to generate an image on the photoswitchable film such that the photoswitchable film is operable to retain the ink on the image for transfer to a tangible medium. A visible light source is then used to erase the image from the photoswitchable film after transfer of the ink to the tangible medium. The photoswitchable film includes a layer of fluorinated azobenzene molecules operable to form the image when exposed to the ultraviolet light and erase the image when exposed to the visible light. The photoswitchable film also includes a bonding layer operable to bond the fluorinated azobenzene molecules to the surface of the lithographic printing plate.

Abstract: Methods and systems herein provide for calibration of a production printing system that accommodates a plurality of different print paper types, including new paper types with no ICC profiles or optical density curves on file. One exemplary method includes printing test patches of primary colors on a first print medium, measuring colors of the test patches printed on the first print medium to determine an optical density of the first print medium, and comparing the optical density of the first print medium to a plurality of optical density curves to identify a comparable optical density curve of a different print medium. The comparable optical density curve is one of a plurality of optical density curves installed on the production printing system. The method further includes automatically selecting the comparable optical density curve to calibrate the production printing system to the different print medium for use in printing to the first print medium.

Abstract: Non integer scaling of images to reduce artifacts is presented herein. One embodiment includes determining a scaling resolution based on a pixel resolution of the image and a pixel resolution of an output device (i.e., factors of the scaling resolution). The image is converted to the scaling resolution to change (e.g., increase) the pixels of the image by the first factor. A grid is generated to scale the converted image. The grid has a number of sections defined according to the second factor times the pixel resolution of an output device. The converted image is sectioned according to the grid. Each section of the grid includes an integer number of pixels of the converted image. The color values of the pixels of the converted image are averaged within each section of the grid to compute a single color value for each section of the grid and scale the image.

Abstract: Methods and apparatus herein provide for automated calibration of multiple printheads used in a multi-pass printing system. Aspects hereof print a plurality of gray scale printed patterns each printed pattern corresponding to a gray scale value for each of the multiple printheads. The printed patterns are then measured to determine the intensity (e.g., optical density) of each of the printed patterns. A measurement function is derived from the measured intensity and gray scale levels used to print each pattern. Calibrated transfer functions are then determined from the measurement function and target function where each calibrated transfer function relates, for a corresponding printhead, an input gray scale level of a pixel in an image to be printed to a calibrated gray scale level to use for the corresponding printhead when operating in multi-pass mode.

Abstract: A method and system for providing a halftoned image is disclosed. The method and system comprise scaling the halftoned image by performing pel repetition utilizing an error diffusion algorithm such that artifacts are minimized. According a system and method in accordance with the present invention performs pel repetition using error diffusion technology, so that any resulting “artifacts” are realized as high-frequency image addition, making them much less visible. A system and method in accordance with the present invention provides adjustability in the computational complexity of the scaling, so that quality can be traded off continuously against the amount of processing power required.

Abstract: Methods and systems herein provide for reducing artifacts during printing. One printing system is operable to prepare a continuous tone image (CTI) for printing onto a print medium by generating an initial half tone image (HTI) based on the CTI. The printing system includes a printer and a print controller. The print controller filters the initial HTI and the CTI with a perceptual filter and determines an error between the filtered CTI and the filtered HTI. The print controller prints the HTI via the printer to determine printer artifacts and processes a scanned version of the printed HTI to determine an error between the filtered CTI and the scanned and filtered HTI. This processing updates the initial HTI and reduces the error between the filtered CTI and the filtered HTI.

Abstract: A halftone spot function, for determining a shape of a halftone spot as a function of the intensity of an image being printed, is generated by creating one or two line segments forming a part of the shape of the spot function or by creating a number of contour lines that are interpolated to form the function. A halftone spot pattern is generated as a number of supercells, each of which includes a number of halftone spots, each defined within a halftone spot cell by a halftone spot function, with the supercell being defined to include a number of device pixels, each of which is fully inked of left without ink, a number of spot cells in each direction, and offset distance establishing angles of the lines dividing the spot cells from one another.

Abstract: A method and system embeds an image into two images by performing a digital halftoning process on a Cartesian product of color spaces.

Abstract: A method of embedding an image into two images by performing a digital halftoning process on a Cartesian product of color spaces to embed the image into the two images. A digital halftoning process includes an iterative isotropic halftoning process. The iterative isotropic halftoning process for each iteration if Outimage has not changed between two iterations or maximum number of iterations reached, then exit the iterations loop.

Abstract: A system for configuring a first printer according to the grayscale printing characteristics of a second printer is described. Grayscale printing characteristics of a first and a second printer are characterized, and a transform between the grayscale printing characteristics of the first printer and the grayscale printing characteristics of the second printer is generated. This transform is used to modify the first printer grayscale commands so as to emulate the grayscale printing characteristics of the second printer.