Abstract: The screened printing data are subjected to a filtering method, the raster information being maintained. Intermediate tonal values are produced by the filtering method, using the binary tonal values, the intermediate tonal values being configured in such a way that, by means of a color space transformation, transformed tonal values and/or intermediate tonal values can be formed which represent a true-to-color proof.

Abstract: A method for generating a dispersed cluster screen defining a stable environment for printing an image is provided. The method initiates with generating a pattern of cluster centroids. Then a cluster growth sequence is defined. Next, a cluster is grown around the cluster centroid according to the cluster growth sequence. A computer readable medium having program instructions for generating a dispersed cluster screen and an image forming device configured to print an image according to a dispersed cluster screen technique are also provided.

Abstract: Characteristics of text or text components or features are considered when selecting halftoning screens. For example, an italic slant angle of text is recognized and used to select or generate a compatible halftone screen oriented at the same angle. A screen frequency may be selected based on a thickness of a text component. Descriptive tags associated with text or text components facilitate screen selection. Tags are assigned based on font descriptions included in a document during authoring. Alternatively, tags are assigned based on the results of document segmentation and character recognition techniques. An image processing system operative to consider characteristics of text or text components when selecting halftone screens includes a text component characteristic recognizer, a halftone screen selector and a halftoner. Optionally a print engine is also included. In a xerographic environment the print engine includes a xerographic printer.

Abstract: A threshold array having an array of thresholds for reproducing a gradation with a dot pattern as a clustered pattern of dots each made up of one or more blackening pixels is corrected. At least one non-contact point candidate position to be turned into a non-contact point is determined among contact points of the dots. Then, at least one contact point candidate position to be turned into a contact point is determined among non-contact points of the dots at the given gradation. Thereafter, the threshold array is corrected by switching around a threshold for the non-contact point candidate position and a threshold for the contact point candidate position, whereby the layout of contact points of the dots can be corrected.

Abstract: An image processing method and apparatus for generating a gray level rendered pixel value that has been subjected to a halftoning process. In the method and apparatus a gray level pixel value of the pixel to be rendered by the halftoning process is provided as one input to a lookup table. A coordinate value that is determined from a pixel location in the image of the pixel to be rendered by the halftoning process is also provided as a second input to the lookup table. The first and second inputs represent an address in the lookup table of a rendered halftone value for halftone rendering of the pixel having the input gray value and the pixel location in the image.

Abstract: The present invention relates to the manipulation of differential gloss as may be inherent in halftoned images by utilization of tags. By selectively applying halftones with anisotropic structure characteristics, which are significantly different in orientation while remaining identical in density, as directed by tag settings, a gloss image may be superimposed within an image without the need for special toners or paper. Conventional copier systems will not typically be able to copy such a superimposed gloss image.

Abstract: A method and apparatus for de-screening a halftone image, therefore allowing the recovery of an approximation of an original image, is disclosed. A method according to one embodiment first performs a screen conversion filter upon a scanned representation of the halftone image to produce an intermediate image. This method then performs a line smoothing filter upon the intermediate image to produce an approximation to the original image. In an alternate embodiment, the method performs a single convolution filter upon a scanned representation of the halftone image to produce an approximation to the original image. In this embodiment, the single convolution filter is equal to the resulting convolution of first performing a screen conversion filter and then performing a line smoothing filter.

Abstract: The present invention overcomes the limitations of the prior art by providing a system and method for halftoning using time-variable halftone patterns. Successive frames that are presented to the output device are individually halftoned. The halftone pattern is changed from frame to frame. The different halftone patterns can be generated in real time, or they can be calculated prior to halftoning and stored in memory. Additionally, the halftone patterns can be generated using any conventional halftoning technique. The same halftoning technique can used to create each halftone pattern, or the halftoning techniques can be varied when creating halftone patterns. The halftoned frames are then viewed in a sequence in time. Because the halftone pattern is changing from frame to frame, the visibility of the pattern is reduced when compared with the patterns produced by prior art halftoning methods.

Abstract: The present invention relates to the manipulation of differential gloss as may be inherent in halftoned images. By selectively applying halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density, a gloss image may be superimposed within an image without the need for special toners or paper. Conventional copier systems will not typically be able to copy such a superimposed gloss image.

Abstract: A halftone threshold matrix includes a plurality of submatrices, wherein a first group of the plurality of submatrices has a line screen frequency different from a second group of the plurality of submatrices. The halftone method and apparatus removes the restriction that at most one pel is turned on per basic cell for the next constant input level and allows the pels in some basic cells to be turned on much sooner that the corresponding positions in other basic cells. This creates a dominant low frequency line screen simultaneously with the higher frequency line screen of the other basic cells. The present invention also allows the basic cells inside the threshold matrix to have different shapes and sizes. Thus, the cells participating in the low frequency screen could be larger than the cells generating the higher frequency screen. For example, the low frequency screen's pleasing patterns can distract the eye from noticing less pleasing patterns in the high frequency grid and vice versa.

Abstract: Halftone image data is generated according to a threshold array in which thresholds T up to a given gradation have been determined, and candidate pixels to be blackened are then determined. Then, a low-frequency component extractor extracts low-frequency component data from density image data which simulates the density of the halftone image data corresponding to an output image from an image output apparatus. A particular frequency component divider 70 divides the extracted low-frequency component data into particular frequency component data for intensifying the low-frequency components, and blackening candidate pixels for intensifying the particular frequency components are excluded, thus narrowing down candidate pixels. The positions of thus determined blackening candidate pixels are determined as the positions of thresholds for a next gradation.

Abstract: There are disclosed a halftone dot producing apparatus in which a phase of halftone dots is freely set up in at least one color plate of the color plates. The halftone dot producing apparatus has an image pixel position deriving section for deriving pixel positions (i, j) associated with values G (i, j) of multi-tone level image data, a threshold pixel position set up section for setting up the pixel position of the associated threshold table to a position in which the pixel position is shifted by the phase (?i, ?j), a threshold table selection section for selecting the threshold table, a threshold set up section for setting up a threshold associated with the pixel position of the threshold table in accordance with the selected threshold table, and a comparison section for comparing the threshold set up by the threshold set up section with the value G (i, j) to produce value D (i, j) of halftone dot image data.

Abstract: The present invention relates to the segmentation of an image into a main area and a image segment for variable glossmark data. By selectively applying halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density to the image segment, a variable glossmark may be superimposed within an image with reduced processing and storage requirements.

Abstract: A system and method for the halftoning of gray scale images by utilizing a pixel-by-pixel comparison of the image against an anisotropic stochastic screen is disclosed. The anisotropic stochastic screen comprises a non-deterministic, non-white noise function which, when thresholded, is designed to produce anisotropic dot patterns having a power spectrum characterized as having negligible low frequency components and a high-frequency region which has an absence of stronger dominant spikes.

Abstract: A screening method includes the steps of cutting off two corners facing each other of square cells to form non-regular hexagonal cells, combining plural of the hexagonal cells into one halftone cell. Further, an interior of the hexagonal cells can be divided in order to form sub-matrices. For a square matrix of 6×6 pixels, 2×2 pixels on the left-upper side of the square matrix of the 6×6 pixels and 2×2 pixels on the right-lower side thereof may be cut down, and thereby one hexagonal cell of 32 pixels not being of a regular hexagon is formed. Further, four hexagonal cells can be combined into one. In such a way, a complex hexagonal cell can be formed. Further, a hexagonal sub-matrix of 8 pixels, also not being of a regular hexagon, can be formed. The center cell of the hexagonal sub-matrix is set to an auxiliary point. Furthermore, three hexagonal cells can be combined into one halftone cell. The number of the halftones which can be expressed by such a halftone cell is 72.

Abstract: A method for copy retouching digital image data which contains a periodic pattern, includes calculating a distance vector D1 from the initially defined starting positions of a read mark and a write mark. The image data are then copied from the image points located under the read mark to the image points located under the write mark. In order to avoid a possible offset of the copied pattern area with respect to the surrounding pattern, a corrected distance vector D2 is calculated in such a way that the read mark and the write mark have the same phase position in relation to the periodic pattern. The method is particularly suitable for copy retouching of screened color separation data.

Abstract: A method of automatically selecting screen characteristics value to be used for printing a color image, comprising the steps of: forming a digital representation of the color image, the digital representation comprising a plurality of separations; dividing at least one of the plurality of separations into a plurality of regions; and assigning at least one screen characteristic value to each of the plurality of regions.

Abstract: The present invention relates to protecting printed items intended for public exchange having important informational indicia provided therein. The print items are protected from tampering by providing an informational indicia image as a glossmark. By selectively applying halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density to render information indicia, a glossmark image is produced of the information indicia. Such an information indicia glossmark image when provided in print item image helps protect that print item image from tampering.

Abstract: An image forming device according to the invention produces a continuous gray-scale image by using a dither matrix structured by orderly tiling a plurality of dither patterns. In each dither pattern, a plurality of gray level areas are arranged in the laser scanning sequence, in correspondence with the gray levels. Dither patterns are arranged in the dither matrix such that a gray level area at the end, with respect to a laser beam scanning direction, of at least one row of one dither pattern is adjacent to the next higher gray level area of another dither pattern. By the use of such a dither matrix, the image forming device forms dots continuously in the laser scanning direction, in correspondence with the gray levels.

Abstract: Systems and methods that shift the halftone screen relative to the image data in the low-addressability direction to compensate for misregistration would be useful. In various exemplary embodiments of the systems and methods of this invention, each pixel of the halftone cell is first divided into high-addressability pixels at the high-addressability factor. The high-addressability factor is the ratio between the base resolution and the high-addressability resolution. The high-addressability pixels are then divided into subrows using the same high-addressability factor. Each high-addressability pixel in each subrow is then assigned its own threshold value. By shifting the threshold values between adjacent subrows based on the subrow, a particular halftone pattern in the low-addressability direction is implemented.

Abstract: An image forming system for suppressing the generation of moiré effect of a print image, provided with a receiving apparatus for receiving an image data of a document, a printer controller for detecting a screen angle of a document image based on the image data, selecting from a plurality of dither patterns a dither pattern with a screen angle different from the detected screen angle and setting the dither pattern, and a printer for reproducing a quasi-halftone using the dither pattern set up by the printer controller.

Abstract: The present invention relates to providing a designer with the tools for the manipulation of differential gloss in halftoned images. A special mask layer is provided for the rendering of desired glossmark image data. The desired glossmark image data is used to select between two halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density. This selection is made for each corresponding portion of primary image data. In this way, a halftone image of the primary image is generated with glossmarks imbedded therein which will display differential gloss without the need for special toners or paper.

Abstract: Disclosed are apparatus and methods for implementing polar halftone techniques that substantially reduce or eliminate interference patterns while printing on rotating circular media with a radial print system. In one embodiment, Cartesian image pixels are selected such that screen pixels or “dots” are arranged fan-shaped along radii (or “spokes”) and in annular ring segments (or “arcs”). Halftone sampling frequency may be varied along spokes and arcs or along a polynomial curve relative to the center of spinning media, in order to reduce distortion and artifacts.

Abstract: The image data output from an image processing section 32 is corrected by a correcting section 33 and the corrected image data is input to a pulse width modulating section 34.

Abstract: A process for color printing an image with angled half tone screens and a colorant set that includes Cyan, Magenta, Yellow and Black colorants and at least one other colorant having a hue angle intermediate the hue angles of Cyan and Magenta.

Abstract: This invention is a method of multilevel dither screening in a printer. Plural pixel values are packed into equal sections of a first data word. Corresponding dither values are packed into the equal sections of a second data word. These first and second data words are added in an arithmetic logic unit selectively spilt into the equal sections. Each section of the sum data word is saturated to all 1's. A predetermined number of least significant bits of the saturated sections are truncated. The resulting normalized pixel values are quantized into a limited set of threshold ranges. This dithering process serves to introduce an amount of scattering to the input pixel values to reduce quantization and pixelation artifacts in the final printed product.

Abstract: A continuously variable screening tool is used to generate a unique texture pattern for every color in a multicolor image. The continuously variable screening tool allows a single colorant version of the image to be generated with less information loss than typically suffered in the multicolor to single color transformation process. The continuously variable screening tool is generated by blending patterns from a set of reference screens. The reference screens are associated with selected reference colors in, for example, a machine independent color space. A calculated screen is generated through a weighted blend of reference screens located near the arbitrary color in the machine independent color space. Typically, the weights depend on the distance the arbitrary color is from each of the reference colors. The screens consist of arrays of threshold values. Each threshold value is associated with a dot position and an image pixel.

Abstract: An electrophotographic apparatus which represents halftone through use of halftone spots formed of a plurality of dots, to thereby reproduce an image and which forms a virtual development region of a predetermined area at a predetermined location within dots by means of exposure of a photosensitive drum to a beam and which reproduces a real development region by causing toner to adhere to the virtual development region. In order to prevent an area narrower than a predetermined width from arising in the virtual development region, an area which is originally designated to become narrow is formed into an area of certain width, to thereby prevent formation of a much narrower real development region, which would otherwise be caused by an excessively low surface potential of the narrow area. The area of halftone spots is partially increased in the virtual development region at a single gray-scale level.

Abstract: The invention provides methods for using single-cell non-orthogonal cluster screens to satisfy the moiré-free conditions for four-color halftoning. The selection of these single-cell halftone screens is determined by identifying combinations of four of the halftone cells which satisfy moiré-free conditions provided in the respective frequency equations. Constraints may be applied and the combinations not meeting such constraints can be removed.

Abstract: An amount of print substance in a printing device as well as an amount of print substance that should be in the printing device are identified. A difference between these amounts is determined and the difference compared to a threshold value. A determination that print substance has been removed from the printing device is made if the difference exceeds the threshold amount.

Abstract: A color image forming device and method prevent occurrence of pile height moires specific to electrophotographic images in low-frequency areas and conventional moires in a digital screen set of four colors. In the color image forming device, by at least one of a halftone generating part and scanning signal forming unit in an image processing unit, differences among screen angles of three dot patterns corresponding to cyan, magenta and black toner images are in the range about 25 to 40 degrees, preferably 30 degrees; the screen angle of a first dot pattern corresponding to a yellow toner image is made equal to that of a second dot pattern corresponding to the toner image of one of cyan, magenta and black; and the screen of the first dot pattern is brought about 150 to 210 degrees, preferably about 180 degrees out of phase with the screen of the second dot pattern.

Abstract: A method and graphical user interface system provide fault notes in a printing system. A fault screen window is provided that depicts faults for individual supply unit devices and output unit devices which can be opened by selecting the fault button and/or fault icon. A fault notes window is also provided for user editable text linked to the fault screen window. The fault notes window displays only user editable text related to a selected device or displays only user editable text related to the system when no device is selected. A fault notes icon is configured to appear when user editable text has previously been entered on said fault notes window.

Abstract: A main CPU reads out CMY values as ? correction patch data from an NVRAM, and outputs a ? correction patch from a color printer section via a ? correction patch output section. The output ? correction patch (sheet) is read by a color scanner section 1 as RGB image data. The RGB image data is converted to CMY color signals by a color conversion section 131 and input to the main CPU via a buffer memory. The main CPU calculates patch read data from the CMY color signals and compares it with the ? correction patch data stored in the NVRAM. The main CPU then calculates an inverse function of a curve of the patch read data and forms ? correction tables of four colors, C, M, Y and K. The ? correction tables are used for full-color ? correction. On the other hand, the main CPU performs an arithmetic operation (error correction) of an error correction table h(x), with an output of black (K) at screen angle ?63° being f(x) and an output of mono-color black (K) at screen angle 90° being g(x).

Abstract: A threshold arrangement capable of reducing a moiré pattern produced by an interference between the output resolution and halftone frequency of an image outputting apparatus is determined. Halftone dot image data is generated by a threshold arrangement determined up to a certain gradation, and low-frequency component data is extracted from the halftone dot image data by an FFT, a LPF, and an IFFT. The position of a threshold where the extracted low-frequency component data is smaller is determined as the position of the threshold for a next gradation. The process of determining the position of the threshold is a process in a real space, and can determine the position of the threshold for the next gradation accurately. The threshold arrangement thus determined minimizes a moiré pattern which is an unwanted low-frequency component in a gradation image that is generated using the threshold arrangement.

Abstract: A color image signal is generated and an arbitrary color in the color image signal is set as a color to be converted. A color after conversion is designated. The color to be converted or a color similar to the color to be converted is converted into the color after conversion or a color similar to the color after conversion. By this processing, a color-converted image, in which a conversion boundary is unnoticeable, can be produced.

Abstract: There is disclosed an image processing apparatus in which a pattern table stores a plurality of screen patterns which include a predetermined number of pattern data and have different data patterns. An in-pattern position calculator generates an in-pattern position signal indicating a position of an input image signal in the screen pattern from main and sub scanning synchronizing signals. A pattern selecting signal combining section generates a pattern selecting signal for selecting a specified pattern in the pattern table from the input image signal, combines the pattern selecting signal and the in-pattern position signal supplied from the in-pattern position calculator, and supplies an address in the pattern table. A controller reads pattern data corresponding to the address in the pattern table from the pattern table and supplies image data.

Abstract: In a digital camera, a CPU divides a multi-valued image into blocks and selects object blocks, which are to be the object of processing. A CCD outputs luminance values of the multi-valued image. A low luminance threshold value setter sets low luminance threshold values on the basis of mean luminance values of blocks adjacent to the object block. A mean luminance value calculator calculates mean luminance values using luminance values from which luminance values that do not reach the low luminance threshold value in a block have been removed. A binarization threshold value setting circuit sets a binarization threshold value of the block based on the mean luminance values. A binarizer then binarizes the multi-valued image in the block on the basis of the binarization threshold values.

Abstract: Method of printer color error correction employing the rapid alternate viewing of a scanned original color image file and an image file formed by scanning an image printed by the printer whose error is to be corrected. Color errors appear as a blinking or flickering feature in the viewing monitor. Adjustments are made to the original color image file to eliminate or minimize flicker. The adjusted color file is then employed in printing a color corrected image. Another embodiment provides the method of the invention for real time color correction in images printed on conventional or digital printing presses.

Abstract: An image processor includes conversion table storage for storing a plurality of conversion tables to determine a correspondence relationship between image reproduction data, including development area information, and tone data; halftone processing for receiving the tone data of respective colors and then finding, for each color, the image reproduction data at each dot by referring to one of the conversion tables; and an image reproducing engine for reproducing images by receiving the image reproduction data at each dot for each color and by determining a development area at the dot on the basis of the development area information included in the image reproduction data.

Abstract: A program with complete conditions for a usable mask yields a unitary mask, each try. One mask pattern is used throughout an image, but may be “tiled”. Preferably the program, for given mask position, expresses favorability of several candidate pass numbers as a “neighborhood constraint” in the form of a weight; distills the weights into one weight for each pass number; based on that, chooses a number for the position; and iterates for all positions. Many preferences are very useful, e. g. automatically balancing randomness vs. determinism, and several generalized relative notations. Another invention facet uses an input text file of mask constraints; a program reads constraints from the file, applies them, forms a mask and stores/uses it. Another reprocesses a mask for best image quality, fixing its own imperfections of first-round mask forming.

Abstract: A RIP system (100) includes a multi-screening information generator (102) for generating a multi-screening information file (Dms) which is an XML-format file containing information such as screen ruling, dot shape and screen angle, necessary for assigning a multi-screening operation, and discloses the multi-screening information file (Dms) to outside of the RIP system by storing in a shared disk or a flexible disk. On an input data creation process side, a client machine makes reference to the multi-screening information file (Dms), and thereby assign the multi-screening operation.

Abstract: Historically, the creation of digital line screens was considered to be a subset of the creation of the digital cluster dot screens. The geometric constraints necessary for digital cluster dot screens were imported into the creation of digital line screens. Accordingly, the number of available angles or digital line screens was also significantly limited. In various exemplary embodiments of the systems and methods according to this invention, a digital line screen cell is defined such that the vectors defining the digital line screen cell are not necessarily isometric and are not necessarily at right angles to each other. By using a high-addressability grid that has different resolutions along x and y axis of the grid, the systems and methods according to this invention allow the components of the vectors along the high-addressability direction to be noninteger multiples of the components of the vectors along the other direction of the grid.

Abstract: The invention provides a procedure that is applicable to various halftoning methods, which minimizes image distortion introduced by the halftoning process. The procedure involves maintaining specific relationships between the halftone pattern and the phase and resolution of the input image. Specifically, that the halftone pattern is designed such that it does not bias tone reproduction with respect to the location of the input image pixels—each input pixel should be given equal weight when filtered by the halftoning process. This suggests a 1 to 1 relationship between each pixel of the input image and the corresponding tone output produced by the halftoning process. The procedure results in improved print quality, manifested by avoidance of certain types of moiré which are commonly associated with halftoning, as well as improved reproduction of edges and image details.

Abstract: A method/algorithm enables the rapid development and tuning of multi-level and multi-frequency halftone screens to improve printer performance. The screens are primarily directed to laser printers. The method/algorithm generally involves generating a lattice of points by selecting a plurality of points along an imaginary line whose path extends along a surface of a geometric shape; assigning a dot shape to each of the lattice points; selecting a growth model for each dot shape; quantizing the lattice points and assigned dots to a specified grid of pixels; and generating multi-frequency screens from the lattice of points and associated dots.

Abstract: A stochastic halftone pattern has been invented which has a narrow band power spectrum due to the incorporation of a dot growth process. The narrow band power spectrum may be matched to the resolution characteristics of specific printers, resulting in smoother printed halftone textures. The spectrum of a halftone pattern may be made anisotropic (angularly dependent), helping to de-couple sets of patterns for color printing with reduced color noise or mottle.

Abstract: A raster image processing system (20) for producing the appropriate number and set of halftoned color separations for a select output device (24) is disclosed. The raster image processing system (20) includes a processing unit (30), an interpreter (32) and a color combiner (34). The interpreter (32) and color combiner (34) are application processes that are controlled by software running on the processing unit (30). The processing unit (30) identifies the number and set of colorants used to describe input image data and the number and set of halftoned color separations that a select output imaging device (24) is capable of rendering. The interpreter (32) converts the input data describing an image that is composed of “N” colorants into “N” halftoned color separations. The color combiner (34) thereafter converts the N halftoned color separations into “M” halftoned color separations that are ideally suited for the particular output device (24) chosen by a user of the system.

Abstract: The present invention relates to providing a designer with the tools for the manipulation of differential gloss in halftoned images. A special mask layer is provided for the rendering of desired glossmark image data. The desired glossmark image data is used to select between two halftones with anisotropic structure characteristics which are significantly different in orientation while remaining identical in density. This selection is made for each corresponding portion of primary image data. In this way, a halftone image of the primary image is generated with glossmarks imbedded therein which will display differential gloss without the need for special toners or paper.

Abstract: Techniques for black and white pattern rendering that increase processing speed and reduce memory requirements while providing improved pattern selection performance are provided. The hue angle and lightness of a color input are determined. The hue angle is used to index into a lookup table of halftone functions that specify default frequency and spot functions for a hue angle range. For each selected halftone, the determined hue angle is substituted from the hue angle range if the determined hue angle differs from the last determined hue angle range by more than a threshold difference value. The determined lightness is used to determine the halftoning threshold value and rendering then occurs.

Abstract: The present invention relates to the manipulation of differential gloss as may be inherent in halftoned images by utilization of tags. By selectively applying halftones with anisotropic structure characteristics, which are significantly different in orientation while remaining identical in density, as directed by tag settings, a gloss image may be superimposed within an image without the need for special toners or paper. Conventional copier systems will not typically be able to copy such a superimposed gloss image.

Abstract: A method to detect frequency and angle of a binary halftone pattern. The method employs an exclusive-or operation which is applied locally to a region of a binary bit map and its spatially shifted version. The resulting bits from the exclusive-or operation are summed over the region. The exclusive-or operation is repeated for a range of shift values. In a halftone region, the shift at which the minimum sum occurs reflects the angle and the frequency of the halftone.