Abstract: An image processing apparatus for performing processing that rounds down C bits from an A-bit image, and that causes a B=(A?C) bit image resulting from the rounding down processing to be displayed comprises a time dithering unit configured to express a pixel value that is an intermediate value of one step in the (A?C) bits in the A-bit image by selectively outputting in each frame across N frames a value where the intermediate value was rounded down and a value where the intermediate value was rounded up, and to artificially express the A-bit image with a dither pattern where the N frames is a minimum unit, wherein the time dithering unit sets the value of N so that M/N is 25 or more.

Abstract: A shading correction device includes first and second extractors, an intersection calculator, a phase shift amount calculator, a phase shifter, a generator, and a corrector. The first extractor extracts a first periodic component of original shading data. The second extractor extracts a second periodic component of a second reading result. The intersection calculator calculates a first intersection of the first component and a reference level and a second intersection of the second component and the reference level. The phase shift amount calculator calculates a phase shift amount at each of plural positions with a difference between the first and second intersections. The phase shifter shifts a phase of the first component with the phase shift amount. The generator generates corrected shading data including the phase-shifted first component and the original shading data with the first component smoothed. The corrector performs shading correction based on the corrected shading data.

Abstract: An image processing apparatus includes a target value calculation unit configured to calculate a target value to be output in a predetermined region in input image data based on pixel values of pixels included in the region, a distribution order determination unit configured to determine a distribution order of output values for distributing output values corresponding to the target value in the region based on a pixel value of each pixel included in the region and a threshold value in the threshold matrix corresponding to the pixel, and an output value determination unit configured to determine an output value of each pixel included in the region by allocating the target value to at least one pixel included in the region in the distribution order.

Abstract: Techniques for improved image disparity estimation are described. In one embodiment, for example, an apparatus may comprise a processor circuit and an imaging management module, and the imaging management module may be operable by the processor circuit to determine a measured horizontal disparity factor and a measured vertical disparity factor for a rectified image array, determine a composite horizontal disparity factor for the rectified image array based on the measured horizontal disparity factor and an implied horizontal disparity factor, and determine a composite vertical disparity factor for the rectified image array based on the measured vertical disparity factor and an implied vertical disparity factor. Other embodiments are described and claimed.

Abstract: An electrophotographic image output device includes an image processor to receive input image data, and a line screen to represent halftone images and have multiple screen angles respectively allocated to different colors including yellow, magenta, and cyan. The line screen satisfies requirements of (A) a predetermined difference is secured between adjacent two of the multiple screen angles; (B) zero is not allocated to any of the multiple screen angles; and (C) among the multiple screen angles determined by the requirements (A) and (B), a screen angle closest to 90 degrees is allocated to yellow among yellow, magenta, and cyan.

Abstract: A control device performs: acquiring an optical measured scan value; setting a measured offset using the measured scan value by reference to predetermined correlations; and determining a control value using the measured offset amount. The control value is used for controlling an amount of colorant to be ejected during printing. In the predetermined correlations, a first pair of scan values is associated with a first pair of offsets. A second pair of scan values is associated with a second pair of offsets. The first and second pair has a first and second scan difference between the scan values, respectively. The first and second pair of offsets has a first and second offset difference between the offsets, respectively. The first scan difference is different from the second scan difference. The first offset difference is same as the second offset difference.

Abstract: An image processing apparatus and an image processing method are provided. When a display apparatus is in the 3D display mode, a mode-switching unit adjusts the way to generate a vertical-count-value by counting every two rows of pixels and outputs the adjusted vertical-count-value. A dither unit outputs a carry value corresponding to the adjusted vertical-count-value. An adding unit adds the carry value and the surplus pixel bit together.

Abstract: A contone source image is processed to create halftone outputs by identifying intensity thresholds based on the coordinates of the pixels of the source image. The halftone output corresponding to a particular pixel of the contone image in a particular color plane is determined by comparing the intensity of the pixel and any previously accumulated output error to the intensity threshold corresponding to the pixel.

Abstract: A printing apparatus which forms dots, according to dot data generated through comparison of a grayscale value of each of pixels with each of threshold values of a dither mask. The printing apparatus forms the dots through division into a plurality of pixel groups having different printing conditions and performs at least a part of the dot formation by the pixel groups in a common region. The dither mask has a second threshold value disposition, with respect to a first threshold value disposition which is each of dispositions of the respective threshold values set such that distribution of dots formed in the common region has noise characteristics having a peak on a high frequency side, in a case where a relative position of the dots between the pixel groups is formed in a target positional relationship which is a target in at least a part of a printing grayscale region.

Abstract: An image forming apparatus includes: an image processing unit acquiring image data, performing image processing, and generating color image data for respective colors; plural toner image forming units each forming and developing an electrostatic latent image on the basis of the color image data, and forming a color toner image; and a toner image holding member moving while holding each color toner image. Each electrostatic latent image has pixel rows arranged in a slow scan direction, with pixels aligned in a fast scan direction. The image processing unit performs, on the color image data, image processing to add or delete the pixel rows for a position of the electrostatic latent image in the slow scan direction. The number of the pixel rows corresponds to the amount of change in a moving velocity of the toner image holding member when each color toner image formed at the position is held.

Abstract: Provided is a method and apparatus to request that an image be printed, where the image is stored in a mobile device, such as a cellular phone, which is able to capture the image. The method includes creating a markup document indicating a panoramic image in which a plurality of images are united, and requesting that the panoramic image be printed, by transmitting the created markup document. Accordingly, a panoramic image may be easily created even in a mobile device having an insufficient memory resource and low specification hardware.

Abstract: A computer readable storage medium stores a tint block image generation program for generating tint block image data for forming, on a print medium, a tint block image including a latent image portion which is reproduced by copying, and a background portion of which copy output density drops. The program has a latent image portion generation step of generating data of a plurality of first dots in the latent image portion based on a dot clustered screen; and a background portion generation step of generating data of a plurality of second dots and data of a plurality of third dots dispersed among the second dots and having a size smaller than the second dots. And the first dots in the latent image portion and the second dots in the background portion are arranged at positions on common displacement vectors in an area of the tint block image.

Abstract: A contone source image is processed to create halftone outputs by identifying intensity thresholds based on the coordinates of the pixels of the source image. The halftone output corresponding to a particular pixel of the contone image in a particular color plane is determined by comparing the intensity of the pixel and any previously accumulated output error to the intensity threshold corresponding to the pixel.

Abstract: A process for printing substrates includes assigning image dots of printer-ready copy to pixels of a multilevel map and assigning values to the pixels depending on the tonal value of the image dot for assigning n+1 different values, where n>1. Artifacts are prevented in multilevel printing processes by assigning threshold values of any threshold value matrix to the pixels of the multilevel map on which the printing is based with respect to their positions relative to the printing substrate, calculating tonal values of the image dot, fixing the values of the pixels depending on the threshold value and the tonal value of the assigned image dot, and printing the multilevel map on a printing substrate in a multilevel printing process, with different values representing different amounts of ink of a printed pixel. A screen assignment device assigns a value to a pixel of a multilevel map generated by an RIP.

Abstract: A printing control device includes an input image data acquiring unit, a threshold acquiring unit, a determining unit, and a generating unit. The input image data acquiring unit acquires input image data. The input image data includes a plurality of input pixel data. Each input pixel data has an input value. The determining unit determines, for each input pixel data, a difference related value based on a difference between the input value and a threshold value corresponding to the input value. The generating unit generates print data by generating, for each input pixel data, output pixel data based on the difference related value. The output pixel data expresses density corresponding to the difference related value.

Abstract: An image processing apparatus may include a first screen processing unit, a moiré component calculation unit, a first correction unit, and a second screen processing unit. The first screen processing unit performs screen processing on image data to form screen processed image data. The moiré component calculation unit calculates an original moiré component that corresponds to a low-frequency component of the screen processed image data and a low-frequency component of the image data. The first correction unit corrects the image data based on a calculated moiré component. The second screen processing unit performs the screen processing on the corrected image data.

Abstract: Methods for mapping color data having at least one color associated therewith to an output device based on an input-device profile and an output-device profile, each profile having a tone curve and a color matrix, are provided. In one embodiment, the method includes receiving color data from an input device and determining whether the color data is in a linear space. If it is determined that the color data is not in a linear space, the method further includes applying the tone curve of the input device profile to the color data to convert it into a linear space. The method further includes converting the color(s) associated with the color data from the input linear space to an output linear space by applying the color matrix of the input device profile and the inverse color matrix of the output device profile to create color-converted image data.

Abstract: An image forming device includes a density detector that detects image density, and a memory that stores information relating image density to dot size. When a dot size is specified, the image forming device automatically obtains the corresponding image density from the information in the memory, prints a test pattern, compares its density with the density corresponding to the specified dot size, and adjusts an image forming parameter until the density corresponding to the specified dot size is obtained. Dot size can be accurately adjusted in this way without the need for elaborate measuring equipment. In particular, the size of dots used to embed invisible information in images can be accurately controlled.

Abstract: Provided are a data processing method and a data processor for ink jet printing, which are capable of achieving uniform and high-quality images while stabilizing density and color development in each of pixels. To this end, a mask pattern for setting permission and non-permission to print dots in each area is arranged non-periodically by using an integral multiple of m×n areas as one unit. The m×n areas allow one pixel to be expressed in half-tone. Thereby, density in the pixel is stable since a plurality of dots printed in the same pixel are printed approximately in the same event. Moreover, since each of the units (clusters) is non-periodically arranged, a uniform image can be obtained.

Abstract: An image forming apparatus includes an image forming unit that forms an image using an electrophotographic process; a color measuring unit that measures a color of the image; a measured-value acquiring unit that acquires a measured value that is measured by the color measuring unit; and a set-value deciding unit that decides a set value related to formation of the image based on a difference between the measured value and a preset target value, wherein the set-value deciding unit determines the set value so that the image approaches a reference value in a period from a current state of the image to desired state of the image while optimizing a constraint evaluation function related to a constraint condition for the formation of the image by using an estimation equation for approximating time-series variation in a state of the image.

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: A method of processing a continuous tone image includes using a halftone screen to generate a bi-level bitmap; partitioning the contone image into an array of image blocks; halftoning the image blocks; using the bi-level bitmap to select some of the halftone image blocks; and modifying the selected halftone image blocks using code words, such that information contained in the code words is embedded in a halftone image. A method of extracting embedded information in a halftone image includes accessing a bi-level bit map; partitioning the halftone image into a plurality of image blocks; using the bitmap to select at least some of the blocks; identifying a code word sequence in the selected blocks; and extracting the information from the code word sequence.

Abstract: A method for controlling an image processing apparatus includes obtaining image data from a detachable memory unit, estimating whether the obtained image data is image data read by a scanner, and in a case where it is estimated that the obtained image data is image data read by the scanner, performing control not to execute predetermined screen processing on the image data.

Abstract: A method and system of color management for an image marking device. A sensor measures printed hardcopy colors. A first gain, computed by a linear controller based on a linear model, is scheduled for each color node of a sampled color space. For each node where a convergence error exceeds a threshold, a second gain is scheduled by a nonlinear controller. The second gain scheduling includes initializing operational parameters, and performing an iterative procedure. The iterative procedure includes computing gain matrices over a defined projection horizon, evaluating a cost function for each gain matrix, determining the cost function, scheduling a new gain based on selecting a gain matrix having the minimum value of the cost function, and computing new CMYK values based on the new gain. A multidimensional LUT based on the scheduled gain matrices is generated and stored in memory, and a hardcopy output image is generated based on the stored multidimensional LUT.

Abstract: An apparatus, system, and method for image processing are disclosed, each of which obtains a mark from image data, detects additional information in the mark, determines whether the mark is detected in the mark to generate a determination result, and controls processing performed by an image processing apparatus with respect to the image data based on the determination result.

Abstract: Systems and methods are provided for processing at least one document comprising color data. Color data in the document in a first color space is inspected to determine if a color space conversion operation for a portion of the color data is specified using a color space dictionary or a transformation matrix, wherein the color space conversion operation converts the color data from the first color space to an intermediate standard color space. An input profile corresponding to the color conversion operation is generated, wherein the input profile comprises information to convert color data from the first color space to the intermediate standard color space; and color space conversion operations are performed on the color data using the generated input profile to convert the color data from the first color space to the intermediate standard color space.

Abstract: A method for using a processor to process image data received from an image data source in preparation for multipass printing, comprising multitoning the image data to produce a multitoned image, using the multitone level of a pixel in the multitoned image to select a plane of a print mask, using the location of the pixel in the multitoned image to select a cell of output pixels in the selected plane of the print mask, and copying the selected cell of output pixels to corresponding locations within a print buffer.

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 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: Aspects of the present invention relate to creation, modification and implementation of dither pattern structures applied to an image to diminish contouring artifacts. Some aspects relate to dither pattern structures with pixel values in a first color channel pattern that are spatially dispersed from pixel values in a corresponding pattern in a second color channel. Some aspects relate to application. Some aspects relate to systems and apparatus for creation and application of these dither pattern structures comprising pixel values dispersed across color channels.

Abstract: Provided are a data processing method and a data processor for ink jet printing, which are capable of achieving uniform and high-quality images while stabilizing density and color development in each of pixels. To this end, a mask pattern for setting permission and non-permission to print dots in each area is arranged non-periodically by using an integral multiple of m×n areas as one unit. The m×n areas allow one pixel to be expressed in half-tone. Thereby, density in the pixel is stable since a plurality of dots printed in the same pixel are printed approximately in the same event. Moreover, since each of the units (clusters) is non-periodically arranged, a uniform image can be obtained.

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: A device for creating print data utilized by a printer is disclosed. The print data includes a coordinate at which a dot is to be formed on a print medium by the printer. The print data creating device is provided with a first device and a second device. The first device chooses a first coordinate from bit-mapped data. The bit-mapped data includes a plurality of combinations of the first coordinate and color information. The first device chooses the first coordinate based on the color information being combined with the first coordinate. The second device creates the print data by converting the first coordinate chosen by the first device into at least two second coordinates which are randomly chosen from at least three second coordinates located in the neighborhood of the first coordinate.

Abstract: This disclosure describes methods for using embedded auxiliary signals in documents for copy detection and other applications. In on application, the auxiliary signal is formed as an array of elements selected from a set of print structures with properties that change differently in response to copy operations. These changes in properties of the print structures that carry the embedded auxiliary signal are automatically detectable. For example, the changes make the embedded auxiliary signal more or less detectable. The extent to which the auxiliary data is detected forms a detection metric used in combination with one or more other metrics to differentiate copies from originals. Examples of sets of properties of the print structures that change differently in response to copy operations include sets of colors (including different types of inks), sets of screens or dot structures that have varying dot gain, sets of structures with different aliasing effects, etc.

Abstract: A watermark information embedding apparatus generates a document image from electronic document data that has been input thereto, modifies the electronic document data based upon the document image and embeds information in the electronic document data. The apparatus includes a document image generator for generating a document image from the electronic document data; a document analyzer for detecting layout information of each constituent image in the generated document image; a normalization information calculation unit for calculating normalization information, which is for normalizing placement of each constituent image, based upon the detected layout information; a modification unit for modifying the electronic document data; and an embedding unit for embedding information in the modified electronic document data.

Abstract: An image processing apparatus is disclosed that includes an image processing part configured to perform image processing for causing a printer to print document data, the printer having a nozzle head having a first nozzle group and a second nozzle group, the first nozzle group having multiple K nozzles and multiple nozzles whose positions coincide with positions of the K nozzles in a sub scanning direction, the second nozzle group having multiple nozzles offset in the sub scanning direction from the K nozzles. The image processing part is configured to perform the image processing so that K is prevented from being applied to and one or more colors related to the second nozzle group are applied to multiple dots corresponding to the second nozzle group in a single movement of the nozzle head in a main scanning direction with respect to a gray drawing object contained in the document data.

Abstract: Mapping spectral colors in an Interim Connection Space (ICS) of a full spectral space based on an objective function is provided. A spectral color value in the ICS is accessed, and a spectral gamut boundary of the destination gamut is accessed. The spectral color value is mapped into mapped spectral color value based on minimization of an objective function of coordinates of a first subspace of the ICS, by fixing coordinates of a second subspace of the ICS, subject to a constraint that a result is within the spectral gamut boundary. The first subspace is a null space of a transformation from the ICS to a color space, while the second subspace is an orthogonal complement of the first subspace in the ICS. The constraint is determined by a gamut section that is an intersection of the spectral gamut in the ICS and an affine subspace characterized by the fixed coordinates of the second subspace.

Abstract: A method for printing an input digital image using a digital printer having a set of colorants with substantially the same color but different densities, including a sequence of node points where each of the two or more colorants are either at their maximum or minimum values, setting colorant concentrations such that the color channel output responses corresponding to the sequence of node points are substantially equally spaced in a visually uniform color space; forming colorant control look-up tables to provide smooth transitions in the color channel output response between the sequence of node points; addressing the colorant control look-up tables with the printer code value for each pixel of the input digital image to determine the colorant control signals for each of the two or more colorants; and controlling the digital printer using the colorant control signals to produce a print of the input digital image.

Abstract: A color conversion apparatus receives first image data including first red-green-blue color data in which the possible values of the red, green, and blue components extend beyond the range from 0% to 100%. The first color data are analyzed into first hue region data, the magnitudes of which are adjusted according to the brightness and/or saturation of the first color data to obtain second and third hue region data. The gamut of colors of the first image data is detected, and matrix coefficients are generated according to the detected gamut. The matrix coefficients are used to perform a matrix operation on the second and third hue region data to obtain second color data, thereby converting the first image data to second image data with conversion characteristics appropriate for the gamut of colors of the first image data.

Abstract: Color management constraints on the use of selected hypocolorant(s) and a black colorant in the rendering of a given pixel reduce ink or toner usage and/or reduce pressure on an ink limit. Additionally, the enforcement of this mutual exclusivity between the black and the selected hypocolorant(s) allows screen frequencies and angles to be shared between halftone screens used for the black colorant and a selected hypocolorant. This reduces the likelihood of objectionable moiré associated with the use of hypocolorant colorants in addition to the conventional CMY(K) colorants. In some embodiments, color management constraints prevent the use of black colorant for pixels beyond a threshold lightness or luminance. This constraint allows the use of the selected hypocolorants in the region of color space beyond the threshold. The threshold can be a function of hue and/or chroma. In some embodiments the threshold is a constant.

Abstract: Ink coalescence in inkjet printing is reduced by printing mutually interstitial images using an arrangement of multiple curing stations in combination with multiple printing heads.

Abstract: Mapping spectral colors in an Interim Connection Space (ICS) of a full spectral space based on a colorimetric gamut map in a color space is provided. A spectral color value in the ICS is accessed, and the spectral color value is transformed into a calorimetric color value in the color space. The calorimetric color value is mapped into mapped calorimetric color value in a first subspace of the ICS. Mapping the colorimetric color value includes gamut-mapping the calorimetric color value using the calorimetric gamut map, followed by identifying the color space with the first subspace. An intersection of a spectral gamut in the ICS and an affine subspace characterized by the mapped colorimetric color value is determined, and the spectral color value is projected onto the intersection. The first subspace is an orthogonal complement of a null space of a transformation from the ICS to the color space.

Abstract: A halftoning device that converts an input pixel signal of 8 bits per pixel into an output pixel signal of r bits per pixel(r<8), the halftoning device includes: a gradation correction unit that expands the input pixel signal into an expanded pixel signal of n bits per pixel(n>8); a threshold value array storage that stores a threshold value array having a threshold value of 8 bits; and a threshold value expansion unit that expands the threshold value of 8 bits to expanded threshold value of n bits per pixel. A range of the expanded pixel signal output from the gradation correction unit is matched with a range of the expanded threshold value. The output pixel signal is set according to a comparison of the expanded pixel signal with the expanded threshold value corresponding to the threshold value that is selected for each input pixel signal.

Abstract: Provided are a data processing method and a data processor for ink jet printing, which are capable of achieving uniform and high-quality images while stabilizing density and color development in each of pixels. To this end, a mask pattern for setting permission and non-permission to print dots in each area is arranged non-periodically by using an integral multiple of m×n areas as one unit. The m×n areas allow one pixel to be expressed in half-tone. Thereby, density in the pixel is stable since a plurality of dots printed in the same pixel are printed approximately in the same event. Moreover, since each of the units (clusters) is non-periodically arranged, a uniform image can be obtained.

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: A spot color dictionary is fine tuned or updated. Localized color production models are determined for spot colors of interest to be produced by an associated document processing system or printer. Measurements are made of colors of produced spot colors. Optionally, measurements are made of colors of test patches that are based on perturbations from the colors of the spot colors. In determining a model for the production of a target spot color, measurement data related to colors that are closer in color space to a given target color is given a higher weight than is measurement data related to colors that are further in color space from the target color. Accordingly, the model is localized to the region of color space about the target color and therefore, more accurately predicts a colorant recipe for the target color than would interpolation based on a full gamut, or more general model.

Abstract: This invention provides a method of generating a dither matrix that stores each of a plurality of threshold values in each of elements for determining a status of dot formation of each print pixel of a print image to be produced on a printing medium by carrying out halftone processing on image data.

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: What is disclosed is a novel system and method for reducing process color banding due to printhead non-uniformities in a direct marking device. In one example, a first measurement of a printhead spatial non-uniformity is obtained along a first line in a color space which produces a spatial uniformity when a target primary color is printed alone. A first spatial tone reproduction curve is generated. A second measurement of the printhead spatial non-uniformity is obtained along a second line in color space in a coverage area of a process color which maximally changes a halftone structure of the target primary color. A second spatial TRC is generated. The first and second spatial TRCs are combined using a weighted average which balances the primary and process colors. A modified spatial TRC is generated. The printhead is adjusted at a location of the target primary color according to the modified spatial TRC.