Abstract: A number of colors in a predefined region of an image to be compressed are determined. The predefined region has a plurality of pixels. In response to determining that the number of colors is greater than a first predefined threshold, a lossy compression process is selected dependent on a number of pixels in the predefined region having a predefined color. The selected lossy compression process is applied to the predefined region.

Abstract: A number of colors in a predefined region of an image to be compressed are determined. The predefined region has a plurality of pixels. In response to determining that the number of colors is greater than a first predefined threshold, a lossy compression process is selected dependent on a number of pixels in the predefined region having a predefined color. The selected lossy compression process is applied to the predefined region.

Abstract: A printing apparatus may comprise a print head including nozzles to eject liquid drops, a drop sensor to detect flying liquid drops ejected by at least some of the nozzles, and a controller. The controller is to control at least some of the nozzles to sequentially eject liquid drops while the drop sensor is at a predetermined position relative to the nozzles, to determine the actual position of the drop sensor relative to the nozzles based on a sensor profile including a nozzle location specific signal characteristic of the sequentially ejected liquid drops detected by the drop sensor, and to calculate an offset between the determined actual position and the predetermined position. The controller may take the offset into account in positioning the drop sensor relative to one of the nozzles to detect a liquid drop ejected from that nozzle in a subsequent operation.

Abstract: Font and text management within a document provides utility in authoring and/or printing documents. In one example, a first portion of the document is configured to include text and references to fonts for use in rendering the text. Additionally, a second portion of the document is configured to include a graphical representation of the text.

Abstract: A method of printing double sided documents on a printer device, said method comprising: formatting said document into a form suitable for printing onto first sides of a plurality of media sheets in a single operation; generating a set of user instructions for instructing a human user to manipulate said plurality of media sheets and enter said sheets into said printer device; and printing said set of user instructions.

Abstract: An improved apparatus for checking a plurality of printer nozzles in a printer device comprises: a printer head comprising a plurality of nozzles; a device for detecting at least one droplet of ink sprayed from at least one nozzle of said plurality of nozzles; and a device for performing a sequence of measurements on a first output signal of the detecting device, wherein a determination of performance of the print head is made by analyzing detected output signals produced by one or a plurality of ink droplets passing the detector, the one or plurality of ink droplets containing a predetermined minimum volume of ink, and the sequence of measurements being measured at a plurality of time intervals.

Abstract: A calibration technique, for a printer having a plurality of different color ink printheads, which includes printing and scanning a test pattern. The test pattern is printed by each printhead printing a plurality of swaths having a length and distanced apart from each other. An optical sensor is used to scan the printed test pattern. Calibration is performed for each head by reading the swath length and the relative spacing of the swath and comparing the length to the spacing. This comparison is used to find the directional error for each head.

Abstract: An improved apparatus for checking a plurality of printer nozzles in a printer device comprises: a printer head comprising a plurality of nozzles (400); a means for detecting at least one droplet of ink sprayed from at least one nozzle of said plurality of nozzles (540, 560); and a means for performing a sequence of measurements on a first output signal of said detecting means (520), wherein a determination of performance of said print head is made by analyzing detected output signals produced by one or a plurality of ink droplets passing the detector, the one or plurality of ink droplets containing a predetermined minimum volume of ink, and said sequence of measurements being measured at a plurality of time intervals.

Abstract: A misalignment compensation technique for a dot printer is disclosed. This technique first supplies printing instructions to a printhead for energizing printing elements in various groups (primitives) to print a pattern on a medium. The printed pattern is then detected by optical sensors in the printer. Based on the detection, a position offset error for each primitive is determined. These errors are used to generate a separate time correction for each of the primitives such that, when the printer is used normally, the time period for printing a dot will be advanced or delayed for each primitive so as to align the dots printed by the primitives. In another embodiment, alignment data taken by a manufacturing line sensor is stored in a memory on the print cartridge. After the print cartridge is installed in the printer, a second optical test completes the data needed to create timing correction values.

Abstract: A method and apparatus for correcting for drop placement errors due to relative rotation between an inkjet printhead mounted in a printer carriage and the print media to be printed on comprises first determining the relative contribution to the drop placement error due to rotation of the printhead about the scan axis (Y axis error), then, with respect to any determined Y axis error, applying the same magnitude and sense of correction for drop placement errors while printing in both a first scanning direction of the carriage and while printing in a second scanning direction of the carriage. Errors due to rotation about the Z axis are also corrected for. Preferably the errors are determined by printing and scanning a test pattern.

Abstract: Techniques to compensate for random and systematic errors when measuring dot placement errors. Error accumulation due to scan axis irregularities during printhead calibration is minimized by swapping alignment block positions on the print medium from swath to swath. Print media advances during the calibration are minimized by the use of a moving reference instead of a constant reference; adjacent groups of nozzles are used to calibrate the following group. Only a small media advance is needed to print alignment blocks using adjacent nozzle groups one beside the other to be calibrated. To prevent paper slip accumulative errors when using moving references, the order of the groups of nozzles is swapped from one paper advance to the other. This randomizes for small, unavoidable slips when advancing the paper and prevents error accumulation.

Abstract: A printer apparatus and method of actuating a fluid pump in a printer to deliver fluid to an ink jet printhead without removing the printhead from a printhead carriage particularly useful for priming inkjet printheads using an air displacement pump to deliver air under positive pressure to the printheads. The pump is located proximate a service station on the printer and is automatically actuated by movement of the carriage to service station. The pump may be arcuately positionable to align the pump with a selected one of air passageways provided in a printhead holddown cover on the printhead carriage. Algorithms are provided for locating the precise position of the pump outlet along the carriage scan axis relative to its intended design location and for arcuately positioning the pump relative to the carriage to engage the pump outlet with a selected one of conduits in the carriage connected to each printhead.