Abstract: An example of a printing system is disclosed. The example disclosed herein comprises a plurality of nozzles and a controller. The plurality of nozzles is to eject a printing agent on a substrate to print a print job. The controller is to receive the print job comprising an outline and a fill area to be printed. The controller is also to define a first subset of the plurality of nozzles as a first printing mode to print the outline. The controller is further to define a second subset of the plurality of nozzles as a second printing mode to print the fill area, wherein the second subset comprises more nozzles than the first subset. The controller is further to print the print job based on the first printing mode and the second printing mode.

Abstract: An example of a system for selecting print mode configurations is disclosed. The example disclosed herein comprises an array of nozzles to eject ink, and a controller. The controller is to instruct the array of nozzles to print a plurality of color patches, each color patch being printed using different nozzle setting values. Also, the controller is to receive a sensor signal from each color patch from a color sensor. The controller is further to derive color saturation and/or density measurement information from the sensor signals; and to select a print mode configuration based on the color saturation and/or density measurement information.

Abstract: An example of a printing system is disclosed. The example disclosed herein comprises a plurality of nozzles and a controller. The plurality of nozzles is to eject a printing agent on a substrate to print a print job. The controller is to receive the print job comprising an outline and a fill area to be printed. The controller is also to define a first subset of the plurality of nozzles as a first printing mode to print the outline. The controller is further to define a second subset of the plurality of nozzles as a second printing mode to print the fill area, wherein the second subset comprises more nozzles than the first subset. The controller is further to print the print job based on the first printing mode and the second printing mode.

Abstract: An example of a system for selecting print mode configurations is disclosed. The example disclosed herein comprises an array of nozzles to eject ink, and a controller. The controller is to instruct the array of nozzles to print a plurality of color patches, each color patch being printed using different nozzle setting values. Also, the controller is to receive a sensor signal from each color patch from a color sensor. The controller is further to derive color saturation and/or density measurement information from the sensor signals; and to select a print mode configuration based on the color saturation and/or density measurement information.

Abstract: Examples describe a method in which first and second test patterns are printed onto a print medium. The first and second test patterns each vary in print density in opposing directions. A location is determined along the first and second test patterns having at least substantially equal visual density.

Abstract: The present disclosure discloses a page wide array (PWA) printer (20) particularly but not exclusively for performing print jobs while maximizing print bar performance uniformity within the printer. The PWA printer includes a print bar which can be moved laterally and a controller which causes the print bar to laterally move from a first to a second position and causes the nozzles within the print bar to print an image while the print bar is in the second position without modifying the lateral alignment of the image.

Abstract: A method and system of controlling at least one printbar in a printing system are described. The printing system has one or more of printbars distributed along a media transport. A first image including a reference pattern is generated on a print medium with a first printbar. A pattern is then detected on the print medium. The reference pattern and the detected pattern are used to determine a position of the first image relative to a second printbar. This position is used to configure nozzle data for a second image to be generated on the print medium by the second printbar.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a colour sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the colour sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: A printer for printing on a print medium as said print medium advances through a print zone, the printer including a number of print heads extending over the print zone, each print head including at least one nozzle array wherein at least two adjacent nozzle arrays overlap forming at least one stitching zone in the overlap region; and a printer controller for generating a sequence of nozzle firing commands for each nozzle array to selectively deposit droplets of print fluid on said print medium from said nozzle arrays in accordance with an image to be printed, wherein the printer controller further applies masks having decorrelated patterns to said sequence of firing commands for at least those overlapping nozzles of the nozzle arrays coinciding with the at least one stitching zone to obtain a predetermined optical parameter of the printed image in the stitching zone, irrespective of an offset between two adjacent nozzle arrays.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a colour sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the colour sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: Examples describe a method in which first and second test patterns are printed onto a print medium. The first and second test patterns each vary in print density in opposing directions.

Abstract: A method and system of controlling at least one printbar in a printing system are described. The printing system has one or more of printbars distributed along a media transport. A first image including a reference pattern is generated on a print medium with a first printbar. A pattern is then detected on the print medium. The reference pattern and the detected pattern are used to determine a position of the first image relative to a second printbar. This position is used to configure nozzle data for a second image to be generated on the print medium by the second printbar.

Abstract: Example implementations relate to random wave mask generation. Some examples may distribute data points in a mask area based on a probability density function. The probability density function may have a maximum probability density located at a first edge and a second edge of the mask area. Some examples may also identify a wave curve that fits the data points. The wave curve may include oscillating waveforms of varying amplitudes. Some examples may also generate a random wave mask based on the wave curve.

Abstract: According to one example, there is provided a printing system. The printing system comprises a support having a plurality of spaced apertures and a color sensor moveable to measure light from each aperture. The printing system further comprises a controller to control the color sensor to measure characteristics of light emitted through each aperture, and to determine, for each aperture, light calibration data.

Abstract: Examples include estimation of pen to paper spacing (PPS). Examples include an alignment pattern printed on a medium at a target speed, an optical scan procedure performed on the printed alignment pattern to determine values of cross-media misalignment for first and second portions of the alignment pattern, determination of a dynamic swath height error (DSHE) effect value based on the values of cross-media misalignment, and estimation of an amount of PPS based on the determined DSHE effect value and the target print speed.

Abstract: A method and system of controlling at least one printbar in a printing system are described. The printing system has one or more of printbars (160, 190) distributed along a media transport. A first image including a reference pattern (240A, 240B) is generated on a print medium (150) with a first printbar (160). A detector (180) then detects a pattern on the print medium. The reference pattern and the detected pattern are used to determine a position of the first image relative to a second printbar (190). This position is used to configure nozzle data for a second image to be generated on the print medium by the second printbar.

Abstract: Image processing transforms input multi-level image data into output image data having a smaller number of levels (the input and output image data represents images formed of cells). The image processing distributes quantization error of a target cell of the image to neighbor cells in proportions determined by a set of weights. The distribution excludes neighbor cells whose data level is less than a threshold value from receiving distributed quantization error, or allows just a fraction of the quantization error to be distributed to such neighbor cells.

Abstract: Example implementations relate to swath height error compensation. Some examples may determine a density of an image to be printed in an overlap area of a printing material. The overlap area may include target pixels capable of being printed by a first set of drop ejection elements and a second set of drop ejection elements that are redundant to the first set of drop ejection elements. Some implementations may also determine a mask to apply to the first and second set of drop ejection elements based on the determined density, and the mask may designate at least one additional drop to apply to at least one target pixel in the overlap area by at least one of the first and second set of drop ejection elements. Some implementations may also apply the mask to the first set of drop ejection elements and the second set of drop ejection elements.

Abstract: Example implementations relate to random wave mask generation. Some examples may distribute data points in a mask area based on a probability density function. The probability density function may have a maximum probability density located at a first edge and a second edge of the mask area. Some examples may also identify a wave curve that fits the data points. The wave curve may include oscillating waveforms of varying amplitudes. Some examples may also generate a random wave mask based on the wave curve.

Abstract: Examples include estimation of pen to paper spacing (PPS). Examples include an alignment pattern printed on a medium at a target speed, an optical scan procedure performed on the printed alignment pattern to determine values of cross-media misalignment for first and second portions of the alignment pattern, determination of a dynamic swath height error (DSHE) effect value based on the values of cross-media misalignment, and estimation of an amount of PPS based on the determined DSHE effect value and the target print speed.