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 system for displaying a digital video sequence includes a graphics processing unit (GPU) and a display device. The GPU receives and modifies the digital video sequence to compensate for perceived blur based on motion between frames of the digital video sequence. The display device displays the modified digital video sequence. A method and computer readable medium having computer readable code is also provided.

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: An image processing apparatus comprises a processor for quantizing multi-gradation image data with regard to each of R, G and B to convert it into pseudo halftone output image data. First, the processor performs a first quantization for deciding a dot appearance pattern C(B)i,j[k] with respect to an observed pixel of the multi-gradation image data with regard to blue. After that, the processor performs a second quantization for deciding the dot appearance pattern of green with respect to the observed pixel so as to make an anti-correlation with the dot appearance pattern C(B)i,j[k] decided by the first quantization.

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: An image reading device capable of detecting foreign particles on a transparent member by including the transparent member, a conveyance unit that conveys an original document to the transparent member, a reading unit that reads via the transparent member an image of the original document being conveyed on the transparent member at multiple reading positions that exist with a prescribed distance therebetween along an original document conveyance direction, an output unit that outputs signals for different color components corresponding to each of the reading positions, a transparent member moving unit that moves the transparent member in a prescribed direction such that the original document slides over the transparent member while being conveyed to the reading positions during image reading, and a detector that detects noise components caused by foreign particles on the transparent member based on the output signals from the output unit.

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: 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: In a method for reducing color moiré in digital images, the object is to improve the suppression of color moiré in such a way that effects on edge areas and fine structures are further reduced in that low-frequency beats causing color moiré are detected and attenuated in such a way that correction is carried out only for two-dimensionally extensive areas and the edge areas and fine structures remain excluded to a great extent. A comparison of bandpass energies between the luminance channel and chrominance channels serves as a marking criterion in order initially to determine pixels in which color moiré is present and then to carry out a frequency-selective energy reduction in the chrominance channels at middle frequencies for suppressing the long-wave color moiré.

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 for resizing image data by a determined desired magnification. The apparatus includes an image data inputting section for inputting the image data, a magnification determining section for determining a magnification based on the image size of the inputted image data and the print size, a magnification converting section for converting the determined desired magnification into a combination of a first reduction ratio including 100% magnification, an expansion ratio and a second reduction ratio including 100% magnification, a first image reducing section for reducing the image data by the first reduction ratio by using an averaging operation, an image expanding section for expanding the resultant reduced image data by the expansion ratio by using an interpolating operation, and a second image reducing section for reducing the resultant expanded image data by the second reduction ratio by using an averaging operation.

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: 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 programmable system for dithering video data. The system is operable in at least two user-selectable modes which can include a small kernel mode and a large kernel mode. In some embodiments, the system is operable in at least one mode in which it applies two or more kernels (each from a different kernel sequence) to each block of video words. Each kernel sequence repeats after a programmable number of the blocks (e.g., a programmable number of frames containing the blocks) have been dithered. The period of repetition is preferably programmable independently for each kernel sequence. The system preferably includes a frame counter for each kernel sequence. Each counter generates an interrupt when the number of frames of data dithered by kernels of the sequence has reached a predetermined value. In response to the interrupt, software can change the kernel sequence being applied. Typically, the system performs both truncation and dithering on words of video data.

Abstract: A dithering pattern that is generated based on a spatial operation is used for a Bit-Depth Extension (BDE) technique for preventing contouring artifacts in an image displayed by a display having a bit-depth that-is less than the bit-depth of the image. The dithering pattern can be based on achromatic visual model or a spatio-chromatic visual model. The dither pattern is formed by shaping a pseudo-random noise signal by an equivalent noise visual model that is based on an array of pixels. Alternatively, the array of pixels is based on an image, or a determinate array of pixels.

Abstract: The invention relates to an information carrier, and a system for positioning such an information carrier in an apparatus. This system comprises an optical element (102) for generating a periodic array of light spots (103) intended to be applied to an information carrier (101), said information carrier (101) comprising a first periodic structure (108) intended to interfere with said periodic array of light spots (103) for generating a first Moiré pattern, and a second periodic structure (109) intended to interfere with said periodic array of light spots (103) for generating a second Moiré pattern, analysis means for deriving from said first and second Moiré patterns, the angle value (S) between said periodic array of light spots (103) and said information carrier (101), and actuation means (AC1-AC2-AC3) for adjusting the angular position of said information carrier (101) with respect to said array of light spots (103), from control signals (114) derived based on said angle value (S).

Abstract: A method and system for de-screening an image signal utilizing a bank of filters to provide several increasingly blurred versions of the original image signal is disclosed. At any given time, only two of these blurred versions are created, on a pixel-by-pixel basis. The outputs from the selected pair of blurred signals are then blended together to create a variable blending output that can vary smoothly from no blurring to maximum blurring in a smooth and continuous manner. In addition, the method provides the capability to enhance text and line art by using a variable un-sharp masking mechanism with independent post-blur sharpening control, and the capability to detect and enhance neutral (no-color) output pixels.

Abstract: The invention relates to an information carrier (101) intended to be read and/or written by a periodic array of light spots, said information carrier (101) comprising a data area (105) defined by a set of elementary data areas, a first periodic structure (108) intended to interfere with said periodic array of light spots for generating a first moiré pattern, a second periodic structure (109) intended to interfere with said periodic array of light spots for generating a second moiré pattern, said second periodic structure (109) being arranged perpendicularly to said first periodic structure (108). The invention also relates to an apparatus for reading and/or writing said information carrier (101).

Abstract: A digital copying machine includes a CPU that executes an overall control, a scanner section, a printer section, and an image processing section that executes image processes including image-process magnification alteration. The CPU adjusts a main-scan magnification of the scanner section at 90.9%, sets the image-process magnification alteration in the image processing section at 110%, and executes a control to form an image in the printer section on the basis of image data in which these magnifications are combined.

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 color image reading apparatus reads an original image by a line sensor through sequentially lighting respective light sources of a plurality of colors with respect to a scan line. An analog-to-digital converter converts an analog image signal read by said line sensor to digital image data. A lighting frequency ratio setting part sets the lighting frequency ratio for the light sources such that not all of the light sources are equally lighted. A thinning control part performs thinning control of lighting lines according to the lighting frequency ratio at which the light sources are lighted. A read data combining part combines read data of the plurality of colors according to a predetermined combination, said read data being obtained by the thinning control.

Abstract: The amount of moiré in halftone printed images is reduced using unique moiré intensity functions and moiré vectors in a halftoner. In various embodiments, moiré phase angle zones are determined over the full field of an image and high addressability units in the full-field moiré phase angle zones of the image are adjusted, including in an iterative manner, until they significantly reduce the moiré. A useful relationship between halftoner memory locations and moiré phase angle zones in a full field image is determined. The moiré that occurs in a halftone image is quantified and moiré compensation values obtained are then used to generate an inverse moire amount which is used to compensate for the moiré.

Abstract: In a black character detection processing, RGB data read from a line buffer is converted into YIQ data. For a subject pixel, a subject area centered on the subject pixel is set, and a judgment pixel that has the lowest brightness in the subject area is set. Then, a judgment area is set as being centered on the judgment pixel. If the absolute values of the averages of chroma components I and Q in the judgment area are both less than the corresponding thresholds T1 and T2, the subject pixel is determined as being an achromatic pixel. Black codes are added to fine-line pixels and edge pixels if the fine-line pixels and edge pixels are determined as being achromatic. Thus, the fine-line pixels and edge pixels can be specified as to be printed in black monochromatic ink. Therefore, black character or similar fine-line or edge part images can be outputted with high quality.

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: 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: In a system, such as in a digital copier, for classifying image data derived from an original image, the image data is classified by type. An algorithm is applied to the gray levels of pixels surrounding each pixel of interest. The algorithm determines whether a local maximum or minimum is part of an image of closely-spaced lines.

Abstract: A method for halftoning an image, including receiving image data including a plurality of color separations and comparing image data for first, second, third, and fourth separations to first, second, third, and fourth halftone screens. The screens are characterized by first, second, third, and fourth pairs of frequency vectors, respectively. The fourth pair of frequency vectors is identical to one of the first, second, and third pairs of frequency vectors. Further, the first, second, third, and fourth screens have an associated fill-in sequence, where the fill-in sequence of the fourth screen is such that overlap between the separation corresponding to the fourth screen and the separation corresponding to the one of the first, second, and third screens to which the fourth screen has an identical pair of frequency vectors does not occur until a combined dot area coverage of the separations is greater than 100%.

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: 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: A halftone screening method creates screens of a plurality of colors, where each of the screens is divided into a plurality of cells, and intentionally changes a dot position of certain colors within cells of the screens of the certain colors relative to a dot position of a reference color within a cell of the screen of the reference color, so as to suppress a color tone change caused by positional errors of the screens.

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: A digital image processing method for eliminating Moiré in a digital image divided into pixels holding pixel component values includes selecting a first pixel and defining a pixel window around the selected first pixel. Then, a set of pixels are identified which consist of pixels within the window that have pixel component values within a pixel component value range that is related to the selected first pixel. A pixel component value is calculated based on corresponding pixel component values of pixels in the set of pixels and then this calculated pixel component value is allocated to the selected first pixel.

Abstract: An image processing technique for generating a multi-valued image with fine contours from an input image that is generated by reading, as a multi-valued image, the dotted print contents of printed matter. An image processing apparatus of the present invention generates a contour extracted image by performing the contour extraction process for the input image, and deletes contours from the contour extracted image that satisfy a predetermined condition to generate a partial contour image. Then, the apparatus adds contours to the partial image according to the density distribution of the contour in the partial contour image, and generates a contour added image. By referring to the contour added image, the apparatus superimposes the input image and a smoothed image obtained by performing a smoothing process for the input image to generate a synthesized image.

Abstract: Moiré free color halftoning is achieved through the use of two dot screens and one or two line screens. The line screens may be, for example hybrid line screens. Frequency vectors associated with the screens combine to produce moiré frequency vectors representing moiré frequencies above or below the visual range. In one embodiment lines screens are used to halftone yellow and black separations and dot screens are used to halftone cyan and magenta separations. The dot screens are oriented at 15 and 75 degrees. The line screens are oriented at 45 and 135 degrees. Selected screens and screen orientations minimize screen interaction with mechanical or optical artifacts of a rendering device, thereby minimizing mechanical and optical moiré.

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: Provided is a method, system, program, and data structures for halftoning an input image comprised of at least two input color components. Each input color component provides input intensity values for the color component at pixel locations in the image. At least two halftoning screens are accessed. There is one screen for each color component and halftone output generated by at least one of the screens has a lines per inch (LPI) that is at least approximately twenty percent different than the LPI of halftone output generated by one other screen. The input image is separated into the separate color components. The accessed screen for each color component is applied to the input intensity values for the color component to produce output intensity values for the color component. The combined halftone outputs for all the color components form the output pixels.

Abstract: The tincture of an input image is analyzed, and stable, smooth screen angles are assigned in descending order from the most dominant color. When the input image has dot information, like a print, the two-dimensional frequency components of the input image for C, M, Y, and K are analyzed, screen angles and frequencies which do not interfere with these components are analyzed, and various textures are assigned to the respective colors on the basis of the analysis result. Accordingly, an image which is stable and smooth in tone and excellent in color reproducibility can be output.

Abstract: An image processor of the invention has an object to provide an effective moire suppression by using a spatial filter and an efficient edge emphasis by using a spatial filter. When a spatial filter process is performed for moire removal, a spatial filter processing section of the image processor has a characteristic wherein the MTF presents values of not more than 1.0 for the entirety of the spatial frequencies to be contained in an image, and the minimum value for a moire-causative spatial frequency. This permits the image processor to prevent the quality degradation of the spatially filtered image. When a spatial filter process is performed for edge emphasis, a spatial filter processing section has a characteristic wherein the MTF is flat in an erroneous-judgment frequency band liable to cause an edge extraction error, and exceeds 1.0 at spatial frequencies below a lower limit of the erroneous-judgment frequency band.

Abstract: A system and method descreen halftone images into a continuous tone image while preserving edge detail and reducing initial image blur. The descreening can be applied to monochrome or color images. Descreening is achieved by first using a low pass filter to form a blurred image of the original, which is used to guide future image filtering, but which further filtering is applied to the original image. The intelligent filtering is provided by a Sigma filter, which can be performed in a single iteration and sized and shaped according to values of the blurred image. The system and method can take a block-oriented approach that performs analysis for an entire block of pixels rather than on individual pixels. This further improves the implementation speed of the process.

Abstract: Image defects in a digital image are reduced by a process comprising: providing a digital image data set in the form of a matrix of pixels; selecting a sub-matrix comprising at least a 5×5 matrix of pixels; identifying a pixel within the sub-matrix to be treated as a central pixel; determining a value for at least one optical property in the central pixel; selecting at least four pixels around the central pixel as averaging pixels, at least two of the averaging pixels being in a position in the sub-matrix that is not adjacent the position in the matrix of the central pixel; determining a value for the at least one optical property for the at least four averaging pixels; averaging the values for the at least one optical property for more than one of the at least four averaging pixels to provide an average treatment value for the central pixel; assigning the average treatment value for the central pixel to the central pixel; and storing the average treatment value assigned to the central pixel.

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: 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: The invention provides methods for using single-cell non-orthogonal cluster screens to satisfy the moiré-free conditions for color halftoning. The invention also provides methods that combine single-cell non-orthogonal cluster screens and line screens for moiré-free color halftoning. Particularly, the selection of these single-cell halftone screens is determined by satisfying moiré-free conditions provided in the respective spatial or frequency equations.

Abstract: The invention provides a printing method and apparatus which can reduce moirés and artifacts. The printing method includes an expanding step of expanding a multi-value image in a storage area, and an image forming step of binarizing the multi-value image expanded in the storage area based on a binarization dither matrix pattern wherein the turn-on order of pixels is set so that dots having shapes same as each other individually grow in order from a plurality of points and forming an image based on a result of the binarization.

Abstract: A scanning unit reads an original color image and outputs an rgb signal of the color image. A scanner &ggr; correction unit that converts the rgb signal from the scanning unit into an RGB signal that is a density signal. A color converting unit converts the RGB signal into a CM signal. An edge amount calculating unit calculates an edge amount from the CM signal. A filter processing unit performs an adaptive filtering process for the RGB signal based on the edge amount.

Abstract: An image reading apparatus is arranged to illuminate a transparent or transmissive original with light fluxes emitted by a plurality of light emission parts which differ in wavelength characteristic from each other, to select by means of a reflection mirror the wavelength characteristics of light fluxes emitted from the light emission parts, and to control each of the light emission parts every time a scanning motion is made by an original-placing board relative to an image pickup part.

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: By using negative feedback, moiré patterns can be reduced, or virtually eliminated, from input black-and-white or color original images. In particular, by feeding back an image containing the difference between the original input image and the halftone output with possible moiré patterns, and subtracting the low-frequency part of this image from the original input image, a resultant halftone image can be achieved that has reduced moiré patterns.