Abstract: An image processing method for preparing a document for printing or other further processing. Document images often contain information in several intensity levels. Detecting these levels will help separate logically separate regions in the image. A multithresholding process separates different significant intensity levels in a document image by recursively finding locally optimum threshold locations, and then selecting only the significant thresholds by studying the intensity transitions in the image.

Abstract: A calibration system, for calibrating a printer response to halftone images directed thereto, includes a test pattern, stored in a memory, providing a plurality of samples of combinations of printed spots, printable on a media by the printer; a gray measuring device, to derive a gray measurement of the samples of printed spots; a calibration processor correlating gray measurements with a particular combination of spots, and deriving parameters describing the printer response to the particular combination; generating at least one gray image correction, including a set of correction values selected in accordance with said the described printer response, and a calibration memory, storing the generated halftone patterns.

Abstract: An image processing method for mitigating the effects of show-through in scanning a duplexed document in a duplex scanning system, including: deriving a scanned first side image P from a first side image A of a duplexed document and a scanned second side image Q from a second side image B of the duplexed document, at least the first side image P including a component thereof attributable to show-through from the second side of the document, and storing images P and Q; from second side image Q, generating a representation thereof corresponding to the show-through contribution to first side image P; processing image P to remove show-through as a function of the representation Q, thereby deriving correct image A.

Abstract: Patterns of intelligence detected in a digital image representation are correlated with pattern classes according to a predetermined set of rules for improved pattern identification. Identified patterns are subsequently mapped to classes for continued use of classification.

Abstract: A method for reducing an image of a character or word string to one or more one dimensional signals, including the steps of determining page orientation, isolating character strings from adjacent character strings, establishing a set of references with respect to which measurements about the character string may be made, and deriving a plurality of measurements with respect to the references in terms of a single variable signal, from which information about the symbol string may be derived.

Abstract: A user interface is provided facilitating the entry of at least one destination phone number into a phone number dialing routine. Upon entry of the phone number, the user interface allows a Start command, causing the phone number to be dialed by transmitting appropriate signals to a switching exchange. In the event a charge code is required, the user interface provides for separate entry for charge codes. A controller concatenates the phone number and the charge code number with appropriate timing inserted to allow the switching exchange to utilize the number and charge code.

Abstract: A method and apparatus for reducing marking material coverage in reproduction of edges in a halftoned image, includes the steps of: a) detecting edges in the image using edge filtering; and b) reducing marking material coverage at the detected edges. Interseparation correlation may also be provided, for the purpose of ascertaining whether a detected edge is against a white or no colorant region, in which circumstance, marking material coverage is not reduced. Further described is the reduction of marking material coverage at the detected edges in proportion to the overall coverage in the image region, taking into account the kind of colors (primary, secondary) forming the edge.

Abstract: In an arrangement in which compressed image data including color image information is to be directed to a printer in streams of data including Sample data, Mask data, Color data and Command or instruction data, wherein the compressed data is directed along a bus, data is retrieved from the bus, with instructions from a fetcher which includes direct memory access (DMA), and is directed to several data type specific FIFO memories. A combiner, operating in accordance with instructions stored in a command FIFO, removes data from the Sample, Mask and Constant Color FIFO's in accordance with the desired image requirements as specified by Command data to form an output image.

Abstract: Halftone screens are generated for each separation in accordance with the goal of avoiding overlapping whenever possible. Initially, the black separation is halftoned, generating a dot pattern with a number of ON pixels and OFF pixels in accordance with the area density of the black separation. Next, a first color separation is halftoned, setting a number of the previous OFF pixels to ON. Then, if any white pixels remain, the second color separation is halftoned, setting a number of the previously OFF pixels to ON. If during the processing of the second and third separations, it is determined that no OFF pixels exist to be turned ON, a second layer of color is started, respectively superimposed over the first layer. The third color separation is halftoned in reverse fill-in order, setting a number of the previous OFF pixels to ON. Each layer is started and arranged so that the additional colors forming the dot pattern are not placed on any black areas.

Abstract: A plurality of multifunction devices each having a facsimile function are connected together in a networking arrangement. Upon receipt of a job requiring a facsimile function, such a device initially checks its queues to determine whether there are any current facsimile jobs in the queues which would delay the transmission of the just-received job. If there are none, the job is transmitted in accordance with the device job priority control arrangement. If prior facsimile jobs are present in the queue, the device checks, via its network connection, other networked devices having facsimile capability from a preprogrammed list thereof, to determine whether any of the devices are not busy. In such a case, the job, with facsimile control instruction and data, is transferred to the non-busy facsimile for transmission.

Abstract: A method and apparatus for operating an ink jet printer of the type which prints a swath of the image at a time with each transit across a sheet. An image portion corresponding to a potential swath is examined, particularly determining for each column whether any breaks occur at any point in a relevant portion of the column. If no breaks are found in any single column, the swath and the next swath are printed unidirectionally. However, if breaks are found at acceptable locations in every column, the swath and the next swath can be printed bidirectionally. For each column, the pattern of bits in the column above the break points in each column are directed to the print buffer to be printed in the first swath, while the remaining bits will be sent to a buffer for the next swath. The distance for the next paper advance is calculated, considering the locations of the breakpoints.

Abstract: A color printer calibration method for improving printer accuracy in regions of local non-linearity includes the steps of: a) starting with filled rectangular array of color mappings A.sub.0 mapping printer signals to device independent color space signals; b) empirically deriving a set of color mappings P.sub.i in an area of interest; c) using a set of planes defined by the color mappings of A.sub.0, and the set of empirically derived color mappings P.sub.i, identifying a new set of planes such that each point defined by A.sub.0 and each point defined by P.sub.i is located at the intersection of three planes, the intersection points of this expanded number of planes defining a set of points P.sub.i(expanded) that define a full rectangular array A.sub.1 of mappings including mappings A.sub.0, mappings P.sub.i and mappings P.sub.i(expanded) ; d) storing the mapping A.sub.1 for use in the creation of a new color space transformation LUT for use with the printer.

Abstract: An interpolation calculation requires a plurality of difference signals representing the distances to a set of neighboring colors in space. However, at least some of the plurality of difference signals required for interpolation of a color within the boundary defined by the known color and the set of neighboring colors are also required for interpolation of another color within the boundaries defined by a neighboring known color and its set of neighboring known colors. Accordingly, rather than redundantly storing the difference values, a storage and retrieval scheme is used which only stores non-redundant difference signals, and retrieves from addresses associated with neighboring colors the appropriate difference signals for a given interpolation calculations.

Abstract: A method of improving the contrast in a natural scene image. A relevant histogram of the image is derived for from a selected subset of local histograms representing regions of the image. The signal describing the histogram is operated on with a filter having the characteristic of weakening strong peaks and valleys in the function, but not effecting flat portions of the signal. The filtered histogram signal is used for controlling the TRC mapping in a device at which the image is to be printed. To assure optimum selection of local histograms, regions including the black point and white point of an image are determined and added to the subset of local histograms representing regions of the image.

Abstract: Method and apparatus for providing interpolated image data from original image data represented in terms of pixels, each pixel defined in terms of value and position in an original image, includes an original image input receiving original image data from an original image source; a page memory operatively connected to the input for storing a page of original image received; a source of interpolation parameters indicating: a slow scan initial pixel value Xinit, a fast scan initial pixel value Yinit, a fast scan x offset value FSx, a fast scan y offset value FSy, a slow scan x offset value SSx, and a slow scan y offset value SSy; a bilinear sequencer calculating for each new pixel, from the received parameters a reference pixel within the image, and a pair of interpolation coefficients for interpolating new pixel values; a memory controller retrieving to an interpolation calculator from the page memory a set of original image pixels including the pixel at the reference position, and three other pixels whose po

Abstract: An image processing system for preparing a document for printing which receives multi separation color documents for printing, each discrete area or pixel in the image described by a signal having a number of possible states greater than can be rendered by a selected printer. In such a system, each separation of the image is separately processed with an error diffusion process which takes into account the processing of another separation, if any. Output signals from a separation are used to determine threshold values for at least one other separation. The varying thresholds are used to vary the likelihood of the current pixel being a spot or no spot.

Abstract: A method for processing images for printing includes the steps for each separation, making a pixel level determination of marking material coverage, based on the number of pixels within a given area that are turned on; if a determination is made that too much marking material will be placed within the given area, using a random number function for turning off a fraction of pixels in the area to reduce the amount of marking material that will be used for the given area; and to preventing artifacts from occurring in the pixel reduction step by utilizing a processing order through each given area which tends to randomize the turn off effect. Additionally, the results of the determination are compared for each separation, to determine that the turnoff result allows at least one corresponding pixel among each of the separations to be turned ON.

Abstract: A method for reducing an image of a character or word string to one or more one dimensional signals, including the steps of determining page orientation, isolating character strings from adjacent character strings, establishing a set of references with respect to which measurements about the character string may be made, and deriving a plurality of measurements with respect to the references in terms of one dimensional signal, amenable to identification processing techniques.

Abstract: An image processing system for preparing a document image for printing, each discrete area or pixel in the image described by a signal having a number of possible states greater than can be rendered by a selected printer. In such a system a screening pattern is used which distributes screen values through the image in accordance with the pattern of a space filling curve. Each signal is thresholded against a threshold determined by such ordering and output a signal renderable by the selected printer. A straight forward function relates threshold value in a screen matrix of values and the length of a space filling curve at any point in an image. The nature of certain space filling curves, allows the generation of two reasonably sized lookup tables providing the length of the curve at any point on the page.