Abstract: A method for processing a duplexed document having a first side with a first image and a second side with a second image includes scanning only the first side of the document under a first imaging condition to retrieve first information relating to each of the first image and the second image; scanning only the first side of the document under a second imaging condition to retrieve second information relating to each of the first image and the second image; and determining from the first information and the second information a show-through contribution of the second image with respect to the first side of the duplexed document.

Abstract: A high-resolution printing method includes the steps of determining if a pixel of a plurality of pixels is a true black pixel and positioning the true black pixel in a predetermined column and a predetermined row of a print matrix.

Abstract: A method of printing a high resolution image with a printhead in a multi-pass printing mode includes subdividing the high resolution image into a plurality of low resolution sub-images; subdividing each low resolution sub-image into a plurality of low resolution swath portions; and allocating an amount of a memory for buffer storage, the amount being only sufficient to store data corresponding to less than two of the low resolution swath portions. The method also includes, for each low resolution swath portion: halftoning each low resolution swath portion to generate a corresponding halftoned low resolution swath portion, the halftoning of each low resolution swath portion of a particular low resolution sub-image being performed independently of halftoning the low resolution swath portions of other low resolution sub-images; storing the halftoned low resolution swath portion into the amount of the memory; and printing the halftoned low resolution swath portion.

Abstract: A method of printing dots in an area on a page using a plurality of printing passes of a printhead over the area, includes processing continuous tone data representing an image through N halftoning iterations to generate N halftone patterns of dots for the area; and printing each individual halftone pattern of the N halftone patterns during the plurality of printing passes, with each individual halftone pattern of the N halftone patterns being printed on a different printing pass of the plurality of printing passes over the area.

Abstract: A method of printing dots in an area on a page using a plurality of printing passes of a printhead over the area, includes processing continuous tone data through a halftoning mechanism to generate halftone image data; and processing the halftone image data through a plurality of error diffused shingling masks, each error diffused shingling mask of the plurality of error diffused masks being used once on a particular pass of the plurality of printing passes in printing the area.

Abstract: A method of printing dots in an area on a page using a plurality of printing passes of a printhead over the area, includes processing continuous tone data representing an image through N halftoning iterations to generate N halftone patterns of dots for the area; and printing each individual halftone pattern of the N halftone patterns during the plurality of printing passes, with each individual halftone pattern of the N halftone patterns being printed on a different printing pass of the plurality of printing passes over the area.

Abstract: A method of printing dots in an area on a page using a plurality of printing passes of a printhead over the are, includes processing continuous tone data through a halftoning mechanism to generate halftone image data; and processing the halftone image data through a plurality of error diffused shingling masks, each error diffused shingling mask of the plurality of error diffused masks being used once on a particular pass of the plurality of printing passes in printing the area.

Abstract: A system for halftoning an color image that includes first and second primary colors is disclosed. The system includes a first input-dependent threshold generator that generates a threshold based on the first color. The system further includes a second input-dependent threshold generator that generates a threshold based on sum of the first color and the second color.

Abstract: A method of printing with an ink jet printer includes providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided.

Abstract: A high-resolution printing method includes the steps of determining if a pixel of a plurality of pixels is a true black pixel and positioning the true black pixel in a predetermined column and a predetermined row of a print matrix.

Abstract: A method of printing with an ink jet printer includes providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided.

Abstract: A method of printing with an ink jet printer includes providing a printhead having a plurality of first nozzles with a first size and a plurality of second nozzles with a second size larger than the first size. The first nozzles and the second nozzles are alternatingly disposed in a vertical direction. Print data corresponding to first columns of pixel locations is provided. The print data includes for each pixel location in the first columns both a respective large dot print datum and a respective small dot print datum. One of the respective large dot print datum and the respective small dot print datum is printed at a first pixel location of the corresponding pixel locations in the first columns. Second columns of pixel locations interleaved with the first columns of pixel locations are provided.

Abstract: The invention is directed to an image forming apparatus including a print engine operable in at least two modes, and an access control system connected to and controlling the print engine. The access control system includes an access control key for allowing selective and discriminate switching of the print engine from one of the at least two modes to an other of the at least two modes, such as from an economy mode to a high quality mode, or vice versa.

Abstract: Halftoning algorithms such as error diffusion, blue noise mask, and void and cluster mask are known to produce visually pleasing, random, homogeneously distributed patterns of dots on output devices such as color displays or printers, for example. These algorithms are extended to take advantage of the mechanisms of each that cause a homogeneous distribution of dots of one colorant to produce a substantially homogeneous distribution of dots when using multiple colorants. The number of dots of each colorant are combined to form an output dot level number of dots that is caused to be substantially homogeneously distributed.

Abstract: An error diffusion halftoning technique calculates only two error terms with one being divisible by two and the other being divisible by four. This is accomplished through using a modified Floyd and Steinberg type filter preferably having weights of 8-0-4-4 expressed in clockwise sequence from the origin. The direction of scanning is preferably reversed each scan line.

Abstract: A method of printing on a print medium with an ink jet printer uses a plurality of different color inks including a first color ink. A movable carriage assembly carries at least one ink cartridge. The carriage assembly is movable at a first carriage speed and a second carriage speed across the print medium in a direction transverse to an advance direction of the print medium. An image area on the print medium has a plurality of rows of pixels, with the plurality of rows being adjacent to each other in an advance direction of the print medium and extending across the print medium in a transverse direction. The carriage assembly is moved across the print medium at the first carriage speed and the print medium is simultaneously printed on in at least one pixel within one of the rows of pixels using the first color ink.

Abstract: An apparatus and method is provided for compensating for the effects of thermally induced droplet size variations in ink-jet printers. The apparatus includes a temperature determination unit for determining the temperature of the print head, and a halftone adjustment unit configured to receive the print head temperature from the temperature determination unit and to receive image data in the form of nominal halftone values. The adjustment unit can increase or decrease the number of dots to be printed, and thereby compensate for droplet size variations, either by adjusting the nominal halftone values based upon the temperature or by adjusting a threshold array based upon the temperature. The temperature determination unit can predict the print head temperature by counting the number of dots to be printed by counting the binary halftone values fed to the swath memory.

Abstract: A binary printer for printing halftone color images on a substrate so that the determination of whether to print a dot or to not print a dot of each color ink at each pixel location is based at least in part upon an estimated temperature of the print head. The temperature of the print head may be estimated based upon direct measurement of the ambient temperature and/or direct measurement of temperature of some portion of the print head. Alternatively, the temperature of the print head may be estimated by counting the number of dots fired by the print head.

Abstract: Apparatus and method controls and varies a spacing between multiple print elements, such as ink jet print orifices, in a printing system. A signal representing at least one of an advance speed of a print medium in a feed direction in the printing system and an approximate drying time of an ink after being applied to the print medium is supplied to a controller. A device, responsive to the controller, varies the spacing between at least two print elements on the basis of at least one of the advance speed of the print medium and the approximate drying time of the ink.

Abstract: A thermal ink jet printer has two columns of nozzles in its nozzle plate parallel to the direction of motion of each sheet of media. When the sheet of media is thin such as bond paper having a thickness of 0.1 mm, for example, all of the nozzles are available for printing. When the sheet of media is thick such as an envelope having a thickness of 0.5 mm, for example, one-fourth of the nozzles are available for printing, and these are the nozzles first passed by the sheet of media during its advancement. Each sheet of media has the same feed rate although it takes four times as long for the thick sheet of media to be printed.