Abstract: Before image data are screened for the subsequent exposure of a printing form, files needed for the screening step are changed in such a way that the values of individual elements in the data fields are changed. The number of elements whose values are changed is determined by evaluating contiguous regions within the data fields. These can be, for example, threshold value matrices in which individual matrix elements are set to a value corresponding to the color white, or which, for the half-tones, are calibrated to a reduced value of the full-tone density. In the latter case, the full-tone image points are screened with a frequency-modulated screen.

Abstract: A halftoning process includes: receiving CMYK input pixel data in terms of continuous tone input data values for cyan, magenta, yellow, and black colors converting the CMYK input pixel data to modified CMYKRGB* pixel data that define the input pixel in terms of error-adjusted continuous tone data values quantizing the modified CMYKRGB* pixel data to derive intermediate output CMYKRGB pixel data in which the cyan, magenta, yellow, black, red, green, and blue colors are each defined by either a first quantized value that represents no color or a second quantized pixel value that represents full color converting the intermediate output CMYKRGB pixel data to CMYK output data.

Abstract: A method is disclosed for screening color separations of a lenticular image with a lenticular frequency of the lenticular lenses needed for viewing the lenticular image. An amplitude-modulated halftone image is calculated for each of the color separations at a screen angle and at a screen frequency, the tangent of the screen angle being a rational number. For a specific color separation, a screen angle relating to the direction perpendicular to the image strips of the lenticular image is defined, a pair of whole numbers whose ratio is equal to the tangent of the screen angle is determined, and the screen frequency of the color separation is calculated as the product of the lenticular frequency and the square root of the sum of the squares of the two whole numbers.

Abstract: A printing system is disclosed. The printing system includes an image processor to rasterize a received print job and to perform a halftone by comparing a first threshold value from a threshold matrix to a first image component sample, comparing the first threshold value to a first number of sequential image component samples neighboring the first sample if the first threshold value is less than the first sample and comparing the first threshold value to a second number of sequential image component samples neighboring the first sample if the first threshold value is greater than or equal to the first sample.

Abstract: Disclosed is a method of generating a screen for an image processing apparatus, which reproduces a multi-gradation image in one pixel using a PWM technique for controlling a pulse width and reference position data. The method includes inputting image data with a first resolution, virtually increasing the first resolution to a second resolution using the reference position data, and generating a screen with the second resolution with respect to the image data using two reference vectors based on the reference position data.

Abstract: A method for creating a differential gloss image includes providing first and second anisotropic halftone structures. The first and second anisotropic structures have different orientations. One of the first and second anisotropic structures is applied to image data in a first region of an image to be halftoned. The other of the first and second anisotropic structures may be applied to image data in a second region of an image to be halftoned. A mixture of the first and second anisotropic structures is applied to image data in a third region of the image to be halftoned, whereby when printed, the three regions each have a gloss characteristic which differs from that of the other two regions.

Abstract: Disclosed is a method for generating a basic template utilized to form a screening mask. The method includes adjusting lines per inch or minimum pattern (such as cluster size or density) of a testing template, printing the adjusted testing template by an outputting device, determining if the gray level of the printing result matches a specific gray level, and continuously adjusting the setting of the lines per inch or the minimum pattern when it does not match the specific gray level, otherwise selecting the adjusted testing template as a basic template. The basic template is optimized according to the printing ability of the outputting device, so the printing performance of the outputting device when using the screening mask formed from the basic template can also be optimized, and the minimum color points can be printed faithfully thereby avoiding dropping of the carbon powder.

Abstract: The present invention relates to a device that, in printing of controlling the amount of color materials applied, changes a screen ruling for image formation according to the relationship between luminance and saturation. A first component obtains color component data of a plurality of colors so that the total amount of controlled variable in each pixel does not exceed a first limit amount. A second component obtains color component data of a plurality of colors so that the total amount of controlled variable in each pixel does not exceed a second limit amount by performing color conversion processing different from the color conversion processing with the first component. A third component performs pseudo halftone processing by changing a screen ruling to be applied to the color component data of a plurality of colors obtained by the color conversion processing with the second component from chromaticity of color image data.

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 number of tonal levels representative of a continuous tone image. The system further includes a memory including a LUT having a number of alternative halftone cell arrangements for each tonal level. Each cell of the LUT consists of a number of device dots describing a particular gray value. For each gray value, there are several alternative cells with different arrangements of the same number of device dots. The LUT is configured with the cells of different arrangements in rows. The rows increase in the number of device dots; hence, each column describes halftone cells of increasing tonal values. The system then communicates the image data having a tonal level to the LUT, and randomly selects a halftone cell arrangement to generate a halftone output.

Abstract: An image forming apparatus to save toner, which can increase the sharpness of printed data (for example, images or characters) on a printing medium while achieving toner saving, and a method to control the same. The image forming apparatus includes a determinator, a storage unit, and a halftoning processor. The determinator receives a command signal to print and then determines whether or not the received command signal is a command signal for a toner saving mode. The storage unit stores a halftone table in which an LPI higher than a normal LPI is set. If the received command signal is a command signal for the toner saving mode, the halftoning processor generates and outputs halftoning result by comparing gray level values corresponding to pixels of received input image data with grayscale values of the stored halftone table.

Abstract: An image processor and an image processing method which can minimize variation of color tone or density in an image after screen processing, even if semi-transparency has been specified. The image processor generates semi-transparent image data by overlaying a semi-transparent object on the PDL data to be rendered semi-transparent. Subsequently, screen processing is performed on the semi-transparent image data, by dither processing. Subsequently it is determined whether or not to define the screen processed semi-transparent image data as the image data for printing. If the result of determination is No, the halftone value of the semi-transparent object is modified to be larger than the current value.

Abstract: A method of operating a color printer including using a first set of one-dimensional TRCs or a second set of one-dimensional TRCs with a single set of color tables.

Abstract: A method and apparatus for reducing image artifacts on displays (e.g., electronic paper, etc.) are described. In one embodiment, the method comprises generating pixels of an image for a bistable display using halftoning based on data of one or more previously displayed images.

Abstract: The appearance of a color print viewed under UV illumination is predicted using a target comprising color patches each printed using a known coverage of printer colorant(s). In one case, the target is illuminated using a UV light source and an electronic image of the target is captured using a digital camera or the like. In another case, a spectrophotometer is used both with and without a UV cutoff filter to measure the target. The captured image data or the spectrophotometric measurements are used to derive a UV printer characterization model that relates any arbitrary combination of printer colorants to a predicted UV color appearance value. Metameric colorant mixture pairs for visible light and UV light viewing can be determined using the UV model together with a conventional visible light printer characterization model. A visual matching task is used to determine a correction factor for the UV printer characterization model.

Abstract: The predicted tone response curve for each color channel and halftone is predicted using a binary printer model and stored, wherein the “predicted tone response curve” provides a model based approximation of the actual response for the printer for each addressable pixel location in the spatial range. Also stored is an “average predicted tone response” by averaging the “predicted tone response curve” over the spatial range of the printer. With the “true average” tone response curve, the “predicted tone response curve”, and the “average predicted tone response curve”, an estimate of the true tone response curve for the color channel can then be mathematically obtained, wherein the true tone response curve defines a predicted actual response for the printer for each addressable print location in the spatial range. The “predicted” and “average” tone response curves are obtained using the 2×2 binary printer model.

Abstract: A method is performed to hide a watermark in two halftone images or in a single halftone image. The halftone image contains information of the hidden watermark, and each pixel value of the halftone image is associated with a corresponding offset value. The offset value is determined according to a corresponding pixel value of the watermark and a corresponding pixel value of another halftone image. The offset value is used to compensate a corresponding input value and a corresponding original error value of the halftone image.

Abstract: An image display medium displays an image including a first region having a first composite image. The first composite image includes a first display image and a first latent image. The first display image includes at least one of a first halftone dot image and a first line image having a first linearity. The first halftone dot image and the first line image have such densities as are not reproduced by copying. The first latent image includes at least one of a second halftone dot image and a second line image having a second linearity. The second halftone dot image and the second line image have such densities as are not reproduced by copying. The first and second linearities produce different moiré patterns when the first display and the first latent images are enlarged by a first common optical system.

Abstract: Methods and apparatus are provided for dynamically halftoning image data, substantially in real-time. Halftone threshold values are calculated and stored in memory, and halftone output values are calculated for the portions of the image data that will be displayed on a display device. Halftone screen parameters may be modified, and new halftone screen threshold values may be calculated for any affected halftone screens. For unaffected halftone screens, the previously stored threshold values may be retrieved from memory. In addition, the portion of the image to be displayed may be modified, and the halftone output values of the new portion may be calculated and then displayed.

Abstract: An image processing apparatus for converting a multiple gradation image into a binary or multivalue image by use of an area gradation method according to a screen cell is provided. The apparatus includes a receiving unit that receives an input pixel value of each pixel of the multiple gradation image and position information on the screen cell, an output unit that has a lookup table storing an output pixel value corresponding to the input pixel value in such a manner that an image is formed in which the output pixel value is increased or decreased with an increase in the input pixel value, and a screen line number is kept at a prescribed level with the increase in the input pixel value but a dot position is different, and that outputs the output pixel value at a pixel position on the screen cell corresponding to the position information by referring to the lookup table, according to the input pixel value and the position information received by the receiving unit.

Abstract: The present invention provides a method of generating information embedded halftone screen code. According to this method, massive digital information can be stored through printing on at least one type of print media. The information embedded can be read and recognized simply and reliably. The quality of the images will not be reduced after information embedded. The information printed on the media includes a predetermined array of halftone dots with different morphology including physical and geometrical characteristics, which forms the computer codes to embed information into printed content. The advantages of this invention are: the maximum similarity value can be reduced to under the threshold value according to this method; the recognition performance of the halftone screen code can be improved; and robustness can still be maintained at a high level even though the paper is defected or polluted.

Abstract: A method of producing a printed output on a substrate is provided using a drop emitting device which is adapted to emit a plurality of ink quantities in response to a control signal.

Abstract: In an image output control system of the invention, an image processing device makes image data subjected to a preset series of image processing and supplies the processed image data to an image output device, which then outputs a resulting processed image. The image processing device determines the number of dots to be created in each pixel group, which has a preset number of multiple pixels included in an image, and outputs the determined number of dots as dot number data to the image output device. The image output device stores multiple options for a priority order of individual pixels included in each pixel group for dot formation. In response to reception of the dot number data, the image output device selects one among the multiple options for the priority order, determines the positions of dot-on pixels in the pixel group, and actually creates dots at the determined positions of the dot-on pixels to output a resulting image.

Abstract: A method for encryption of a digital watermark by intelligent halftoning includes receiving image data that define at least a portion of a document to be printed in terms of at least three halftone images corresponding respectively to three printing colorants, each of the three halftone images comprising a plurality of halftone cells. The image data are modified by phase-shifting some of the halftone cells of at least one of the halftone images relative to the other halftone images to encode a watermark within the portion of the document such that the at least one phase-shifted halftone image includes a phase-shifted region and a non-phase-shifted region. The modified image data are used to print the portion of the document on a substrate that will fluoresce when subjected to UV illumination. The printed portion of the document includes a first printed pattern resulting from the phase-shifted region and a second printed pattern resulting from the non-phase-shifted region.

Abstract: Disclosed herein is a method and apparatus for moiré-free color halftone printing with up to five color image separations. The method and apparatus utilize a plurality of non-orthogonal halftone screens to produce outputs that are moiré free and form rosettes.

Abstract: Systems and method for digitally reproducing a moiré-free color halftone output image having an embedded correlation-based digital watermark are provided using an enhanced halftone screen set consisting of a halftone screen for each of N colorants forming N color separations (where N?3). The N different uniform rosette halftone screen configurations are generated such that each meets uniform rosette halftone screen conditions. A corresponding three-dimensional threshold array is generated for each halftone screen configuration having a phase shift value as an input. The color input image is halftoned, halftoning each one of the N different color separations using a corresponding halftone screen configuration and three-dimensional threshold array to form a moiré-free color output image having the correlation-based digital watermark embedded therein. A single key can be used to produce a full color image of the output image having the watermark image visible therein.

Abstract: An image processing apparatus includes an information acquiring portion that acquires information on image process conditions for processing image data, a creating portion that creates additional image data, serving as a watermark image, with additional information to be embedded into the image data on the basis of the information on the image process conditions acquired, and a merging portion that merges the image data with the additional image data to create composite image data.

Abstract: A profile generator determines differences between the standard spectral reflectances of a color chart printed under standard density conditions and the spectral reflectances of a color chart printed while the density of one of the colors C, M, Y, K is changed, and the densities of the other colors are secured to standard densities. When density variations are established, the profile generator generates a print predicting profile using spectral reflectances produced by adding the standard spectral reflectances and the difference with respect to the color whose density has changed. The colors of a print produced when the density of a desired color is changed are predicted with high accuracy using the print predicting profile.

Abstract: In a line by line image forming apparatus, line switching information which depends on scan line curve and an overlap data length to be read that overlaps across a plurality of lines before and after a switching position instructed by line switching information are set in a register. If switching to the line above or below is instructed by the line switching information, an address generating unit, when reading image data from an image memory, generates the read address and read data length of the image memory in accordance with the line switching information and the overlap data length, and reads image data corresponding to a current line and the line above or below the current line in accordance with the generated data.

Abstract: A method for avoiding objectionable moiré in a color image can include identifying a problematic excitation angle associated with a problematic excitation in a marking process or in the color image and selecting a set of at least two halftone screens for rendering at least two separations of the color image wherein the set of screens is selected to avoid including significant screen fundamental, harmonic and beat frequencies at angles closer than about 1 degree of the identified problematic excitation angle. Halftoning the color image according to the selected set of screens avoids objectionable moiré associated with the problematic excitation.

Abstract: A method and apparatus for processing image data representing a color separation or mono-color image includes processing the color separation image data or mono-color image data in accordance with first and second or more halftone screen processings at different screen angles and obtaining results of the processings and combining the results of the processings to generate composite image data of the first and second or more halftone screen processings. The resulting print of the composite image data forms relatively pleasing rosettes or diamond structures in the particular color.

Abstract: A spectral reflectance, corresponding to multiple quantities of coloring materials, is obtained, and a target spectral reflectance, corresponding to data of a color of interest, calculated based on the spectral reflectance. The target spectral reflectance is calculated in a manner that makes the spectral reflectance change contiguously, across an interval of multiple colors that are reproduced by the quantities of coloring materials in question. A decision of the quantities of coloring materials in question is thus made that corresponds to the target spectral reflectance.

Abstract: A three-dimensional halftone screen is provided that is suited for multilevel printing. The three-dimensional halftone screen includes a plurality of planes each corresponding to one or more input intensity levels of an input RIPped pixel. Within the planes are screen dots, each associated with one or more output exposure intensity values representing an intensity of an exposure dot corresponding to the input RIPped pixel.

Abstract: To generate a threshold matrix which is compared with an original image in creating a halftone dot image for each color component, in a matrix area for one color component, dot centers are arranged almost uniformly in a random fashion at a predetermined density and in a matrix area for another color component, dot centers are arranged almost uniformly in a random fashion at a density about 0.7 times the predetermined density. Then, threshold values are set so that dots should grow around the dot centers in accordance with an increase in gray level of the original image, to generate the threshold matrix for each color component. In creating the halftone dot images by using these threshold matrixes, characteristics of spatial frequency of the halftone dot images of these color components can be represented in a frequency space as areas (75K, 75C) in a shape of concentric rings.

Abstract: Disclosed herein is an image processing method for producing enhanced halftone edges, particularly suited to those edges which only lie upon the background as apposed to those edges which abut other halftone screens. It utilizes a step of defining border pixels and a step of halftoning those border pixels in a different manner than the halftoning applied to the interior region of the tint or image segment. The preferred halftone for the border pixels will be related to the interior halftone by some number of common spatial frequency harmonics.

Abstract: What is provided herein are systems and methods for digitally reproducing a moiré-free color halftone image using an enhanced halftone screen set consisting of a halftone screen for each of N colorants, where N>4. Also disclosed is an enhanced color halftoning screening apparatus for reproducing a moiré-free color halftone image using an enhanced halftone screen set consisting of a halftone screen for each of N colorants, N>4. Further disclosed are embodiments for generating a plurality of non-orthogonal halftone screen outputs for moiré-free enhanced color halftoning.

Abstract: Disclosed herein is a method and apparatus for moiré-free color halftone printing with up to four color image separations. The method and apparatus utilize a plurality of non-orthogonal halftone screens to produce outputs that are moiré free and form uniform periodic rosettes. The method and apparatus provide for defining a first and a second color halftone screen fundamental frequency vector for each of three halftone screens such that the halftone screen set output forms uniform hexagonal rosettes; then defining a fourth color halftone screen where a first fundamental vector of the fourth screen shares a fundamental frequency vector with one of said three halftone screens and a second fundamental frequency vector of the fourth screen shares a fundamental frequency vector with a different one of said three color halftone screens.

Abstract: A disclosed image forming apparatus for recording images includes: an image processing unit to create toner image data on four colors of yellow (Y), cyan (C), magenta (M), and black (K) such that toner images have line-shaped periodic structures; and an image forming unit to form the toner images using coloring materials of the four colors and superposing the toner images on a recording medium, wherein the line-shaped periodic structures of the toner images of the four colors are determined based on screen ruling of 200.0, 180.3, 180.3, and 200.0 for Y, C, M, and K colors and screen angles of 0.0, 146.3, 33.7, and 90.0 for Y, C, M, and K colors.

Abstract: To reduce low-frequency moiré in secondary colors and tertiary colors in four color screens, between at least two halftone screens, screen vectors wa2, wb2 are arranged to match each other, while other screen vectors are arranged not to match each other. A halftone screen is an orthogonal screen in which screen vector wa2 is perpendicular to basis vector ra1. A halftone screen is a non-orthogonal screen in which screen vector wb2 is perpendicular to basis vector rb1. When screen vector wa2 matches screen vector wb2, spatial frequency spectra corresponding to screen vectors wa2 and wab2, match each other. With such a relationship, because a pair of spatial frequency spectra can match each other between two colors, wider intervals can be provided for the spatial frequency spectra of the remaining colors of four colors, which would suppress low-frequency moiré.

Abstract: This invention is directed to an image forming apparatus which forms a color image on the basis of image information and includes an image forming unit which forms a color reference image on an image forming member on the basis of reference image information for color correction, a colorimetric unit which measures the color of the color reference image formed by the image forming unit and outputs color information, an image processing unit which generates a gray level correction table on the basis of the color information output from the colorimetric unit, and a control unit which corrects the image information on the basis of the gray level correction table generated by the image processing unit and controls the image forming unit so as to form a color image on the image forming member on the basis of the corrected image information, and an image forming method using the image forming apparatus.

Abstract: A three-dimensional halftone screen is provided that is suited for multilevel printing. The three-dimensional halftone screen includes a plurality of planes each corresponding to one or more input intensity levels of an input RIPped pixel. Within the planes are screen dots, each associated with one or more output exposure intensity values representing an intensity of an exposure dot corresponding to the input RIPped pixel.

Abstract: An image forming apparatus has a color converter, a BG/UCR processor, a Bk/Lk generator, and a halftone processor. The cyan, the black, and the magenta are halftone screens having substantially equal frequencies and angle differences therebetween each set at approximately 30 degree. The light black is a halftone screen, and the light black and the black have a frequency ratio of 1.0 to 1.2, which is the ratio of the higher one of the frequencies of the light black and the black to the lower one thereof, and have the angle difference of approximately 45 degrees.

Abstract: An image processing apparatus includes a storage unit that stores a correction amount used to correct color unevenness of an image according to a plurality of halftone screening conditions; and a correction unit that corrects an input image according to the correction amount stored in the storage unit. The stored correction amount includes common information, which is common among the halftone screening conditions, and dependent information, which is dependent on the respective halftone screening conditions.

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: A multiple beam printer system having N laser beams receives print job information from a print host. A rendering application uses a threshold array to generate halftone image data from the print job. The threshold array is defined based on a spot function. The defined screen is non-orthogonal and includes Y pels in a direction that is perpendicular to a scanning direction of the laser beams where Y is an integer multiple of N. A distance between screen dots in pels is preferably equal to an integer multiple of N. The screen dot may be defined by a supercell encompassing two screen dots and having an odd number of pels in a direction that is parallel to the scanning direction. The spot function may include a snap feature that snaps a screen dot to the nearest printer grid pel. The spot function may include scaling to compensate for the distortion of the non-orthogonal screen dot.

Abstract: An image processing method for reducing jaggy effect, which is applied in an image output device, is provided. Firstly, a continuous tone image is generated, and continuous tone pixels are defined according to a first addressing space. Then, a halftone image is generated. After that, the continuous tone image is low-pass filtered to generate a low-pass filtered image. Next, determine whether a position of the low-pass filtered image whose density is approximate to a pre-determined density. If so, generate a set of second addressing space co-ordinates of a key point corresponding to the position. Then, a moving vector corresponding to the key point is generated so as to regulate the position of a display point of the halftone pixel. Afterward, output the display point according to the position after regulation.

Abstract: The present invention provides an image processor and an image processing method which can minimize variation of color tone or density in an image after screen processing, even if semi-transparency has been specified. The image processor of the present invention generates semi-transparent image data by overlaying a semi-transparent object on the PDL data to be rendered semi-transparent. Subsequently, screen processing is performed on the semi-transparent image data, by dither processing. Subsequently it is determined whether or not to define the screen processed semi-transparent image data as the image data for printing. If the result of determination is No, halftone value of the semi-transparent object is modified to be larger than the current value.

Abstract: A method and apparatus for generating a multicolor image using halftone screens employs a dot structure dot growth pattern for one or more of the colors and a line structure dot growth pattern for at least two or more of the other colors.

Abstract: A printing control method of generating print data to be supplied to a print unit capable of forming dots on a print medium by ejecting ink droplets of at least one type of colored ink containing a color material and a quality-enhancing ink for enhancing quality of a printed material. The printing control method comprises a tone-decreasing step which includes the step of generating transparent dot data by a process configured such that size of first processing-targeted pixels is larger than size of second processing-targeted pixels, the first processing-targeted pixels being targeted for processing in the transparent dot data generating process, the second processing-targeted pixels being targeted for processing in the colored dot data generating process.

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.