Abstract: The invention relates to methods and devices for binary coding and decoding by similarities for structured documents After having decomposed the data to code into a series of symbols, each item of data being at least partially represented by a symbol, and having selected at least one item of data to code, a search is carried out for a first sequence of symbols coded beforehand, identical to a second sequence of symbols to code, comprising a symbol representing a part of said data. Similarly, a search is carried out for a third sequence of symbols coded beforehand of which one symbol is distinct from the symbol corresponding to a fourth sequence of symbols to code comprising said symbol representing said part of said data. In response to the comparison of their coding efficiency, the second or the fourth sequence is coded.

Abstract: A pattern generating unit generates correction patterns on a transfer belt. Detection sensors detect the correction patterns, and amounts of magnification correction, amounts of misregistration in the main- and the sub-scanning direction are calculated. The amount of skew between each of colors is then calculated, and a position where an image is divided and a direction for shifting a divided image are determined. Possible dividing-positions are also determined, and a calculated dividing position and each of the possible dividing positions are compared with one another. Then, a possible dividing position closest to the calculated dividing position is set as an actual dividing position.

Abstract: In a printer, threshold matrixes are prepared so that, in a color halftone image generated with the threshold matrixes, cell centers are arranged randomly, a direction where intervals of cell centers for cyan are maximum and a direction where intervals of cell centers for magenta are maximum are different, and the both directions are tilted relatively to a column direction corresponding to a scan direction of a head. A check pattern is recorded with the threshold matrix for each color component by the head, print densities in positions in a width direction of the check pattern, which corresponds to an arrangement direction of outlets in the head, are measured to acquire modification coefficients and then pixel values of an original image are modified by using the modification coefficients. This makes it possible to print a color halftone image with less graininess, without causing a beat pattern and streak unevenness.

Abstract: Exemplary methods are directed to the linearization and characterization of an image producing device. In the method, a color test chart of the device is reproduced and measured based on a small number of color measurement fields with defined device color values. Associated color values are determined for each color measurement field and used to calculate linearization curves for the device. Additionally, by analysis of the device color values, the measured color values, and device behavior, an expanded color test chart with expanded device color values and associated expanded color values is calculated. The number of color measurement fields in the expanded color test chart is larger than the number of color measurement fields in the original color test chart. An ICC profile for the device is calculated from the expanded device color values and the expanded color values.

Abstract: Efficiently processing contone image data by determining one or more characteristics of the image data and using these characteristics to manipulate the dither matrix so that the printed image is enhanced.

Abstract: A method for performing chromatic adaptation includes performing chromatic adaptation wherein corrections to tristimulous values XYZ are maximized in the regions of white and neutral and are minimized in the vicinity of non-neutral regions of colors space via piecewise linear corrections in XYZ. In one embodiment, a selective linear correction is performed using three matrices one for each sector in an RGB color space. In an alternative embodiment, selective color adjustments are made and the adjustments are partitioned for each primary and secondary color.

Abstract: An image processing apparatus comprises: a N-valued conversion unit that converts color component values of plural colors comprised in pixels constituting input image data into N-valued values in a unit of color based on threshold values of the plural colors; a dither matrix storage unit that stores dither matrixes in which one dither pattern or one kind of dither pattern is repeated in a unit of dither pattern; a counter that holds a value specifying a readout position of a row of each dither matrix; and a readout unit that reads out the threshold value of each color used from plural kinds of dither matrixes based on the values from the counter, wherein the number of threshold values constituting a row of the plural kinds of dither matrixes is a common multiple of the number of threshold values constituting a row of the plural kinds of dither patterns.

Abstract: An image is generated by performing area coverage modulation to express a halftone color according to a gross area of dots displayed in a pixel of the image. The image is generated in such a manner that the halftone color is expressed with a selected one of dither patterns corresponding to respective predetermined densities, each of the densities being determined by the gross area of dots calculated in view of shapes of the dots.

Abstract: A color conversion apparatus receives red-green-blue color data, calculates characteristic information and first hue region data from the color data, adjusts the first hue region data according to the characteristic information to obtain second to N-th hue region data, N being an integer equal to or greater than three, generates matrix coefficients for the second to N-th hue region data, and performs a matrix operation on the second to N-th hue region data to obtain color data with four or more color components. Color data with three primary components are thereby converted to color data with four or more primary components by simple calculations, without using a large amount of memory space.

Abstract: A dither matrix is applied to a high-resolution image to compare the value of each of the pixels that compose it with a threshold value of the matrix and to obtain an output value of the matrix (Dither matrix value) from each comparison. To each pixel value of the image there is applied an algorithm involving simple but displacement operation, namely shifts to the left and shifts to the right. The pixel values of a low-resolution image are output from the applied algorithm.

Abstract: A color reduction processing apparatus and method that is simple to configure and adjust produces two-color print image data reflecting the impression of the original full-color image. Each pixel in a full-color image is converted to binarized principal and secondary color print data by principal and secondary color processors respectively using respective threshold value matrices. The threshold values of these matrices, which are calculated from a reference threshold value matrix stored in memory, can be adjusted, via adjustment values, to control the overall density of the principal and secondary colors. The adjustment values can be set in a matrix configuration unit. The binarized principal and secondary color print data can also be further corrected by correction and/or filtering operations performed by a correction processor.

Abstract: The present invention is directed to a system and method for halftone screening. A system for halftone screening includes means adapted to receive image data having a desired number of tonal levels representative of a continuous tone image and means adapted to compress the received image data from a desired number of tonal levels to image data having a lesser number of tonal levels. The system further includes a memory including a look-up table, the look-up table including each of the lesser number of tonal levels and an array containing screen frequency data for each of the lesser number of tonal levels. The system still further includes means adapted for communicating the image data containing each of the lesser number of tonal levels to the look-up table, whereby corresponding screen frequency data is output therefrom.

Abstract: Generation of an Interim Connection Space (ICS) of a full spectral space is provided. A space of illuminants is accessed, and the full spectral space is decomposed into a first subspace that is an orthogonal complement of a metameric black subspace for the space of illuminants. The Interim Connection Space is generated based on the first subspace. The generated ICS can be used, for example, for rendering an image on an additive color destination device. One image rendering workflow includes accessing color data of the image in an ICS, transforming the color data from the ICS into a device dependent color space of an additive color destination device, and rendering the transformed color data on the destination device.

Abstract: Generation of an Interim Connection Space for spectral data in a full spectral space is provided. A set of linear maps is accessed, each linear map characterizing a linear transformation from the full spectral space to a colorimetric space, and spectral measurement data is accessed. The linear maps can for example be determined by a set of illuminants. The full spectral space is decomposed into a first subspace that minimizes a loss of a spectral component in the spectral measurement data under a projection along a second subspace onto the first subspace. The second subspace is a null subspace of the set of linear maps. The Interim Connection Space is generated based on the first subspace. The Interim Connection Space can include, for example, a linear map characterizing a linear transformation from the Interim Connection Space to the full spectral space, and a linear map characterizing a linear transformation from the full spectral space to the Interim Connection Space.

Abstract: A method of processing cyan, magenta, and yellow color values C1, M1, Y1 including transforming the C1, M1, Y1 color values to cyan, magenta, and yellow color values C, M, Y in such a manner that each of C, M, Y is not greater than a predetermined maximum value VMAX; obtaining blue, cyan and magenta output color values B, Cout, Mout by setting B=0, Cout=C, and Mout=M; if the sum C+M is greater than VMAX, obtaining blue, cyan and magenta output color values B, Cout, Mout such that B+Cout+Mout=VMAX; and half-toning B, Cout, Mout and Y using a first threshold array A1 for B, Cout and Mout, and a second threshold array A2 for Y.

Abstract: The number of pixels of a dot of a minimum size, a pattern frequency of an intermediate tone, the number of new dots of the minimum size at each dot percentage are determined. Then, thresholds in the threshold matrix are determined so that the optimum dot pattern at each dot percentage is obtained, and a threshold matrix is generated. A threshold matrix for C-separation is assigned to a separation for R that is complementary to C. A threshold matrix for M-separation is assigned to a separation for G that is complementary to M. A threshold matrix for Y-separation is assigned to a separation for B that is complementary to Y.

Abstract: A halftone reproduction processing section (29) of an image processing apparatus (13) has a control part that conducts a halftone processing of input image data by subjecting it to an error diffusion processing, selects input image data on at most one, namely, one or no input image data from the input image data on at least seven colors, namely, primary colors of cyan, magenta, and yellow used as visible colors for forming an image on a recording medium, secondary colors of red, green, and blue that are the complementary colors of the visible colors, and black, and subjects the input image data on the other colors to a different error diffusion processing.

Abstract: The present invention provides an image processing device which can reduce a storage capacity and perform color correction in accordance with the types of image. The image processing device of the present invention has an input correction section 6 including: input color correction section 24 for, using a matrix coefficient, correcting strength of signals for color components in image data of a supplied image; a matrix coefficient storage section 26 for storing a plurality of matrix coefficients in accordance with types of image; and control section 25 for reading a matrix coefficient corresponding to the type of a supplied image out of the matrix coefficients stored in the matrix coefficient storage section 26 and setting the matrix coefficient that has been read in the input color correction section 24.

Abstract: In order to create a device link profile by which color conversion can be performed with sufficient accuracy even when brightness characteristic equivalent conversion is included, all conversion parameters including the input device profile, the conversion parameters for color space conversion, and the output device profile are divided into a color conversion parameter component FC2 that indicates the parameters for color conversion, a pre-processing component FC1 positioned before the color conversion parameter component FC2, and a post-processing component FC3 positioned after the color conversion parameter component FC2, and if brightness characteristic conversion XLA1 comprising conversion to match the perceived brightness characteristic is included, such brightness characteristic conversion XLA1 is incorporated in the pre-processing FC1 or post-processing component FC3 such that it is not included in the color conversion parameter component FC2, and the pre-processing component FC1, the color conversion

Abstract: A method for generating a dither mask is disclosed using a local stochastic technique for use for the halftoning of grey scale images by a pixel by pixel comparison of the images against the dither mask. The dither mask is generated by producing a sequence of dot profiles (each dot profile of the sequence corresponding to a grey scale level) using a stacking constraint with incremental grey scale level such that for each dot profile of the sequence the same pixels are selected compared to the preceding dot profile and the increment in the or each dot profile is realized by selecting at least one additional pixel. When determining the position of an additional pixel, the aspect ratio between the dot pitch in a predetermined direction and a direction perpendicular thereto when rendering images is taken into account.

Abstract: A method and system are provided for processing digital multi-colour images for the reproduction thereof on a colour printing and/or copying system. Particularly, the printing and/or copying system is capable of complementary forming registered composite multi-colour images of coloured marking particles. This means that the separation images of coloured marking particles are formed contiguous to each other rather than in a superimposed relationship. The digital multi-colour images are processed such that during reproduction thereof any adverse effects on image quality caused by register errors in a predetermined direction are eliminated or at least limited. To accomplish this, a particular halftoning technique is used wherein with gradually increasing input density value of the image pixels, a linear growth pattern is generated in the predetermined direction by alternately adding image dots to both sides.

Abstract: A system and method for printing an image on a document by generating RGB data from a scanned image, converting the RGB data to CMYK data and identifying one of a first and a second type of screening. The type of screening is identified for a first one of the CMYK data based upon the density of the first one of the CMYK data and the density of at least one of the other CMYK data.

Abstract: A print engine/controller suited to use with a drop on demand print head. The print engine/controller works with compressed page data having both JPEG contone image layers and a bi-level image plane compressed using a Group 4 facsimile protocol. It receives compressed image plane's and effects expansion and printing in a pipeline fashion. It consists of a high speed serial interface (27) (such as a standard IEEE 1394 interface), a standard JPEG decoder (28), a standard Group 4 Fax decoder (39), a halftoner/compositor unit (29), a tag encoder (30) by which to place infrared tags into a printed page, a line loader/formatter unit 31 feeding an interface 32 to the print head (33). The decoders (28, 39) and encoder (30) are buffered to the halftoner/compositor (29).

Abstract: An image processing device for processing an input image so as to reproduce a halftone, includes: a matrix setting section for setting a threshold matrix having a plurality of elements arranged in M columns×N rows, at least two threshold values being stored in each of the elements; an element specifying section for specifying a corresponding element of the threshold matrix in accordance with a position of a pixel in the input image; and a multilevel signal generating section for fetching the threshold values from the specified element and for generating a multilevel signal by transforming an input pixel value to one of multiple levels in accordance with the fetched threshold values; wherein the multilevel signal generating section outputs a constant value Doutmin as the multilevel signal when a first condition that the input pixel value is smaller than or not larger than a minimum value of the threshold values, is satisfied; the multilevel signal generating section outputs a constant value Doutmax when a seco

Abstract: It is an object of this invention to prevent a false edge phenomenon in quantization processing for a multilevel image. In order to achieve this object, according to the invention, (1) a reference threshold (Cthreshold) to be used for error diffusion for a cyan (C) component is obtained on the basis of a density value M of a magenta (M) component. (2) A threshold modulation amount table is referred to by using a combination of a density value C of the C component and the density value M of the M component. (3) A correction threshold modulation amount Cthreshold? is determined by adding the threshold modulation amount obtained in the second step to the reference threshold Cthreshold to be used for error diffusion for the C component. (4) A density Ct after error diffusion for the C component is compared with the correction threshold Cthreshold?. If the density Ct is higher, a quantization value binDataC of the target pixel is set to 255. If the density Ct is lower, the quantization value is set to 0.

Abstract: For M (magenta) and C (cyan), in a case of generating, e.g., ternary data of C0 to C2 and M0 to M2 respectively by using a look-up table on the basis of an error diffusion method, in a highlight portion of input M and C data (to which errors Ce and Me have been added respectively), a conversion space of correlating these data is used, while in a high-density portion, a conversion space equivalent to ordinary error diffusion is used. Thus, in a case of converting multivalued color image data into data of a lesser number of bits than the number of bits of color components constituting the multivalued color image data, it is possible to maintain excellent tonality on the entire image, and particularly to control graininess by preventing image quality deterioration in the highlight area.

Abstract: A system and method are provided for processing digital multi-colour images for the reproduction thereof on a colour printing and/or copying system. Image dots of marking particles of the respective colours associated with the respective colour separation images are positioned contiguous to each other as long as the print area corresponding to the image part to be reproduced is not fully covered so as to create a first layer of marking particles. If the area is fully covered and the image is not yet completely rendered, a second and any following layer of contiguously positioned marking particles is formed on top of the first layer of image dots. The halftoning of the digital image is such that within the same layer all images dots, irrespective of their colour, are obtained using a raster of the same matrix structure, while image dots associated with different layers are obtained using rasters of different matrix structures.

Abstract: A method and apparatus for printing a multivalue image in a binary-form output pattern. The printing apparatus employs a binary-form dither matrix pattern which is composed of a greater number of pixels, so that moiré patterns and other artifacts are minimized in printouts. The method includes: providing the binary-form dither matrix pattern for use in obtaining the binary-form output pattern; expanding the multivalue image in a memory area; and forming a binary image of output dot elements in accordance with the binary-form output pattern. The binary-form dither matrix pattern has a rectangular pattern in which a plurality of pattern elements that are numbered to be successively turned on are arranged in matrix. The turning-on sequence is set in such a way that plural groups of prospective output dot elements, which groups are substantially identical in shape, grow successively from a plurality of local points associated with the respective groups.

Abstract: A method for halftoning a gray scale image to generate a halftoned image uses a stochastic screen is designed to provide visually pleasing, blue noise dot profiles when thresholded at any gray level and wherein substantially all the threshold values corresponding to gray levels between gs1 and gs2 coincide with black positions in a constraining checkerboard pattern and substantially all the threshold values corresponding to gray levels between gs2 and gs3 coincide with white positions in the constraining checkerboard pattern.

Abstract: A system and method for creating gamma correction data for a hardcopy device includes generating a data pattern, the data pattern including data representing color pixels and monochrome pixels, dithering the color pixels of the data pattern, and error diffusing the monochrome pixels of the data pattern such that the dithered color pixels and the error diffused monochrome pixels are each N-bit values, N being greater than one. A test pattern is generated based on the dithered color pixels and the error diffused monochrome pixels. The test pattern is scanned into scanned image data, and a plurality of color gamma correction curves and a monochromatic gamma correction curve are generated from the scanned image data.

Abstract: CPU 150 performs a matrix operation on image data GD, and then increases the effective digit place number of the color values of the image data GD to increase the tone number of the image data GD from 8-bit tone to 18-bit tone. CPU 150 performs a gamma correction process, a matrix operation N?1M, and an inverse gamma correction process, and then restores the tone number of the image data GD to the original 8-bit tone, and performs automatic quality adjustment. As a result, the 8-bit tone of the original image data GD is preserved throughout image processing, and reproductive color number of the image data GD is preserved as well.

Abstract: A method and apparatus for performing color halftoning using block quantization is disclosed. In one embodiment, the method comprises dividing an input image into a plurality of blocks, clustering pixels in each of the plurality of blocks into a plurality of color groups, block quantizing each of the plurality of color groups for each of the plurality of blocks to a representative color value, and creating an output halftone image having a distinct block associated with each block in the plurality of blocks, with the representative color value for each group in each distinct block being approximated over a spatial area covered by the group in said each distinct block.

Abstract: There is disclosed a method of dynamic generation of a linearized halftone matrix from a high bit resolution halftone matrix, for use in a printer device, for example a domestic or office printer device or a commercial high resolution printer device. A high bit resolution halftone threshold matrix is converted into a vector format (700). A tone correction function is applied by selecting a variable number of index values, each index value representing a threshold level. A tone corrected two-dimensional 8 bit threshold level matrix, is then applied to a corresponding print image plane comprising a plurality of pixels to obtain a two dimensional print data for each of a plurality of colors of an image. The print data is printed as a plurality of dots by a print head to form a printed image using a halftoning method.

Abstract: An image data of M-gradations in a pixel is converted into multivalued image data of N-gradations (M>N>2) in a pixel. A remarked pixel converted into the multivalued data is determined whether to be a predetermined gradation TJ (N>TJ>2) in which a tone jump occurs. When the remarked pixel converted into the multivalued data is determined to be the predetermined gradation TJ, it is determined whether a pixel of the predetermined gradation TJ exists in pixels being adjacent to the remarked pixel. When the pixel of the predetermined gradation exists, the gradation of the remarked pixel is changed to the gradation other than the predetermined gradation so as to prevent the tone jump, and an average density after multivalued image data conversion is preserved.

Abstract: The present invention relates to an image processing method, an image processing apparatus and a recording medium that convert a grey scale image into an area gradation image. The present invention intends to provide an image processing method, an image processing apparatus and a recording medium capable of increasing processing speed in a state where high image quality is maintained. In the image processing method and the image processing apparatus according to the present invention, image data of a C component and image data of an M component in grey scale image data are converted into halftone image data in accordance with an error diffusion method, and image data of a Y component are converted into halftone image data in accordance with a blue noise mask method.

Abstract: A mask is produced for converting multi-level image data into a halftone image through comparison with a threshold for each pixel. For this purpose, a dot pattern is determined on each of predetermined gray scale levels, and, the mask is created by the dot patterns obtained at the step, where the respective dot patterns are determined independently for every gray scale level.

Abstract: Disclosed is a method, system, and program for managing calibration files in a printing system. Patches are printed using a screening algorithm and incorporating at least one output appearance factor. A calibration file is generated from measured color values of the printed patches mapping a color space for the printed patches to a color space of a printer used to print the patches. Information is associated with the calibration file indicating the printer and at least one output appearance attribute for use in selecting one calibration file to use when printing a print job.

Abstract: A halftone dot image HI composed of halftone dots is produced by halftone dot meshing of an object image OI. A smoothed object image SOI and a smoothed halftone dot image SHI are then produced by smoothing the object image and the halftone dot image. An interference moire image IM is produced by obtaining a difference between the smoothed object image SOI and the smoothed halftone dot image SHI.

Abstract: Apparatus and method for flexible digital halftoning are provided in which novel pattern choices are allowed by not restricting the basic halftone patterns to grow sequentially. Rather, positions in a threshold array allow multiple transitions between on (i.e., printed with toner/ink) and off (not printed) as a function of the input value at the corresponding position. In one embodiment, multiple threshold matrices are employed and the output decision is a vote (e.g., exclusive OR) of the outputs of the individual threshold matrices. In another embodiment, each position contains an arbitrary bit vector to express the output for each input. This flexibility in growing basic halftone patterns allows the number of densities output to be larger than n+1 (where “n” is the number of dots within a basic halftone cell).

Abstract: A printing method and system thereof are described. The locations in a printed image for a plurality of first color (e.g., cyan) dots and the locations in the printed image for a plurality of second color (e.g., magenta) dots are determined. Locations in the printed image for a plurality of third color dots (e.g., yellow) are then determined. The locations for the third color dots are dependent on the locations of the first color dots and the locations of the second color dots. The decision on where to place third color dots is thus made after, and therefore dependent on, the decisions on where to place first color dots and second color dots. Accordingly, color fluctuations in the printed image are minimized, resulting in superior color smoothness and improving the quality of the printed image.

Abstract: A printhead controller controls printing of a page by at least one printhead. The printhead controller, in use, receives data, in a compressed format relating to the page to be printed, the data including a page description comprising a bi-level black layer and a contone color layer. The printhead controller extracts from the compressed data relating to the bi-level black layer the contone color layer. Memory is provided for temporary storage of the expanded data. A dithering/compositing unit produces a ditherer page from the data temporally stored in the memory and feeds its out put to the printhead.

Abstract: A buffer memory has a plurality of blocks which are virtually broken up into a matrix pattern. An image processing apparatus has a memory controller for writing R, G, and B image data in the buffer memory in units of lines and in a predetermined color order, and reading out the R, G, and B image data written in the buffer memory. The memory controller switches operation for writing the R, G, and B image data in the blocks that belong to corresponding rows, and operation for writing the R, G, and B image data in the blocks that belong to corresponding columns in units of lines, and reads out old image data from a region of the buffer memory in which new image data are expected to be overwritten before the new image data are overwritten by the write operation.

Abstract: Improved color management techniques use sample identifiers that define sample color areas having core areas and buffer areas adjacent the core areas. The core area defined by each sample identifier includes a unique set of colors. However, the buffer area defined by each sample identifier is a same common color (e.g., white). Sample color areas can be displayed or outputted (e.g., printed) adjacent to each other to form a region of sample color areas (e.g., a color image, a uniform region of color, etc.). Within such an arrangement, the buffer areas limit any ink bleed between the core areas of the sample color areas thus minimizing, or altogether avoiding, spectral interaction between inks of different core areas.

Abstract: An image processor includes: a color conversion unit for converting an input signal to color signals of at least four colors; a gamma correction unit for performing gamma correction on the color signals; a binarization unit for binarizing the color signals through comparison with a threshold value; a superimposing unit for superimposing a color signal of at least one color but of the binarized color signals on another color signal to convert the signals to a superimposed color signal; logical operation unit for performing a logical operation previously defined for an image of three or fewer colors on the superimposed color signal; and a separator for separating color signals as an output of the logical operation unit into separated color signals of at least four colors.

Abstract: A print engine/controller (10) to drive an ink drop print head has an interface (22) at which to receive compressed page data, decoders (28,88) to decode respective types of image planes in the received compressed page data, and a half-toner/compositor to (29) composite image plane data, the half-toner/compositor including a dot merger unit (58) taking bits from the respective planes as inputs and a color mask register (61) holding masking bits in number equal to the number of image planes, respective input bits to the dot merger unit being ANDed with respective color mask register bits and the resultant bits Ored together to form an output bit in a channel for which there is an ink at the print head. The respective planes to the dot merger unit may include three contone color planes and a high resolution spot plane, and the color mask register is loaded with bits that are selected to place the high resolution spot plane into any one of the respective color channels at the print head.

Abstract: A method and an apparatus to perform replacement halftoning is disclosed. In one embodiment, the method comprises dithering multiple color channels of a pixel of an image to generate a plurality of halftone outputs. Each of the halftones corresponds to a distinct color channel of the pixel. The method further includes creating a virtual color channel from two or more color channels of the plurality of color channels and applying error diffusion to the virtual color channel to generate an error diffusion halftone outputs, and then replacing of the dither output error diffusion halftone outputs.

Abstract: A method and system for jointly designing at least two sets of dither matrices. First, a mosaic color tile is generated for a first concentration level according to a design tile map. The mosaic color tile includes at least a first color tile and a second color tile where each color tile has a color tile concentration level (CTCL) and a color tile number (CTN). Second, a color fluctuation metric is performed on the mosaic color tile. Next, the pixels in the first color tile are modified by an operation (e.g., a swap operation) while maintaining the first concentration level. Then, a color fluctuation metric is re-calculated on the mosaic color tile with all first color tiles being replaced with the modified first color tile (i.e., everywhere the first color tile appears in the mosaic color tile as specified by the design tile map).

Abstract: An image reproduction engine which causes toner to adhere to a development region of certain area located at a certain position within dots according to image reproduction data is utilized for image processing, wherein a halftone is expressed by means of halftone spots formed from a plurality of dots. The centroid of the halftone spot formed from a single dot or a plurality of adjacent dots is shifted from the center of the dot to an arbitrary position, thus achieving desired screen angles or desired pitches of halftone spots. As a result, screen angles related to an irrational tangent can be realized, and the pitches of halftone spots of a plurality of color screens can also be made uniform. 31.

Abstract: A print engine/controller suited to use with a drop on demand print head. The print engine/controller works with compressed page data having both JPEG contone image layers and a bi-level image plane compressed using a Group 4 facsimile protocol. It receives compressed image plane's and effects expansion and printing in a pipeline fashion. It consists of a high speed serial interface 27 (such as a standard IEEE 1394 interface), a standard JPEG decoder 28, a standard Group 4 Fax decoder, a halftoner/compositor unit 29, a tag encoder 30 by which to place infrared tags into a printed page, a line loader/formatter unit 31 feeding an interface 32 to the print head 33. The decoders 28,88 and encoder 30 are buffered to the halftoner/compositor 29.

Abstract: A system and method for creating gamma correction data for a hardcopy device includes generating a data pattern, the data pattern including data representing color pixels and monochrome pixels, dithering the color pixels of the data pattern, and error diffusing the monochrome pixels of the data pattern such that the dithered color pixels and the error diffused monochrome pixels are each N-bit values, N being greater than one. A test pattern is generated based on the dithered color pixels and the error diffused monochrome pixels. The test pattern is scanned into scanned image data, and a plurality of color gamma correction curves and a monochromatic gamma correction curve are generated from the scanned image data.