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 detecting unit detects output-prohibit area information indicating an output-prohibit area from image data. An identifying unit identifies the output-prohibit area in the image data based on the output-prohibit area information detected by the detecting unit. A masking unit performs a masking on the output-prohibit area identified by the identifying unit. A rearranging unit rearranges an image of an area other than the output-prohibit area over the output-prohibit area on which the masking is performed by the masking unit. An outputting unit outputs image data obtained by rearranging the image by the rearranging unit.

Abstract: An image processor includes a tone converter operable when a pixel of input image data is determined as having a value greater in color saturation than a prescribed saturation value. In this operation, the tone converter changes a threshold for each color in a dither matrix associated with the pixel to make the thresholds different in correspondence to color component values of the pixel. The tone converter generates color component values of the pixel constituting image data to be output, based on comparisons between the respective color component values and the changed thresholds.

Abstract: In a matrix area, a plurality of linear areas each of which extends in a tilt direction tilted relatively to row and column directions are arranged in a direction perpendicular to the tilt direction without spaces, and the plurality of linear areas are alternatively assigned to first and second element groups along an arrangement direction. One element is specified in each element group and subsequently process of specifying an element farthest from specified elements, is repeated to acquire a turn-on order of dots with increase in gray level in one grayscale range and a turn-off order of dots with decrease in gray level in the remaining grayscale range, and a threshold value of each element is determined according to these orders. Thus, generated is a threshold matrix capable of reducing graininess in a halftone image with directionality in the tilt direction, and improving the reproduction of thin lines and characters.

Abstract: An image processing apparatus capable of displaying image data on a display device that has resolution lower than that of the image data, includes a processor that categorizes image data of one screen into a plurality of groups by setting two or more pixels of the image data being mutually adjacent on the screen as one group and that outputs data to be displayed time-divisionally and sequentially on one pixel of the display device respectively based on data of the pixels in each of the groups.

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 information processing apparatus processes, for each pixel, multivalued image data for a unit area of a recording medium, so as to form an image on the unit area with a plurality of relative movements between a recording head and the recording medium. The apparatus has a selector that selects a first processing mode for dividing the multivalued image data into a plurality of pieces of multivalued image data corresponding to the plurality of relative movements, and then quantizing each of the plurality of pieces of multivalued image data, or a second processing mode for quantizing the multivalued image data into quantized image data, and then dividing the quantized image data into a plurality of pieces of quantized image data corresponding to the plurality of relative movements. The selector selects the processing mode based on a content (attribute, grayscale, color, etc.) of the multivalued image data.

Abstract: A color image forming apparatus is provided that forms an image by correcting registration shifts during an image forming process by using image data and which prevents toner from being blown away and scattered during a fixing process by thinning pixels without making an erroneous decision. When multivalued color image is binarized, the threshold is corrected by using information on grayscale level correction. Further, when trailing phenomenon prevention operation is performed on the binarized image data, the patterns to be used for pattern matching are changed and selected according to whether the subscan direction line shifting point lies within the reference window.

Abstract: An image forming apparatus performs pseudo gradation processing using dithering, and includes an image carrier; a plurality of light-emitting element arrays arranged in a main-scanning direction and including a plurality of light-emitting elements; an image forming unit performing lighting control of the arrays and forming a pattern image on the image carrier; a detecting unit detecting a density of the pattern image; a position detecting unit detecting a position in the main-scanning direction of the detecting unit with respect to the light-emitting element arrays; a determining unit that, based on the detected position, determines whether the detecting unit is positioned at a proper detection position with respect to the pattern image on which noise has no effect; and an operation control unit that, when the detecting unit is positioned at the proper detection position, performs an image density detection operation on the pattern image using the detecting unit.

Abstract: A method for eliminating moire in scanned digital image comprises the steps of using an average circuit for taking weighted average and error diffusing a gray level difference between an error diffusion pixel Gij and neighbor pixels to neighbor to obtain output image pixel Y?ij; using a second adder for subtracting the error diffusion pixel Gij from the output image pixel Y?ij to obtain a neighbor image error dij; using a error filter H(z) to process the neighbor image error dij to obtain a corrected pixel error H(d(i,j)); and using a first adder for adding the corrected pixel error H(d(i,j)) and the input image pixel Yij to obtain the corrected error diffusion pixel Gij, and then jumping to first step until all pixels being processed. The method provides real time treatment for eliminating moire and provide smooth image.

Abstract: A circuit dithers pixel data on a display, and includes a lookup table module, a dithering parameter decoder, a first adder, a second adder, and an overflow handling module. A lookup table of the lookup table module stores dithering parameters generated by encoding odd and even pixel dithering parameters. The dithering parameter decoder generates second and third dithering parameters corresponding to odd and even pixels from a first dithering parameter. The first adder generates a dithered odd pixel parameter according to the odd pixel parameter and the second dithering parameter. The second adder generates a dithered even pixel parameter according to the even pixel parameter and the third dithering parameter. The overflow handling module checks for overflow, and generates an output odd pixel parameter according to the dithered odd pixel parameter, and generates an output even pixel parameter according to the dithered even pixel parameter.

Abstract: An image processing apparatus is provided that restrains image quality deterioration of image data read with a resolution in a sub-scanning direction set lower than a resolution in a main scanning direction from a document containing text, halftone photographs, line drawings, photographs, etc. An image processing apparatus performs the tone reproduction processing by applying error diffusion processing to the image data that has undergone processing of making the resolution in the sub-scanning direction equal to the resolution in the main scanning direction when the resolution in the sub-scanning direction is lower than the resolution in the main scanning direction and applying dither processing to the image data in other case. When the resolution in the sub-scanning direction is lower than the resolution in the main scanning direction, the halftone processing is applied to the entire image data that sharpness and smoothing processing has been performed.

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: 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: 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: A method for reducing image noise is provided. The procedure of the method is provided in the following steps. First, the color level scale of a scanned image of a document is reduced by a plurality of bits in order to subtract a noise level from the scanned image. Then the color level scales of all pixels of the image are recombined by a halftone pattern method in order to recover the color level scales. Finally the missing codes of the image are filled out by bit enhance method. Because of the color level scales of the proceeding image are not reduced, the scanned image quality does not be blurred by the method. Because the method does not minimize the color level of the proceeding image, the image noise can be reduced without blurring the scanned image and the quality of the image can be increased after the process thereof. And because each color level of the pixel in the image is subtracted by a noise level, some of the bits are removed and the capacity of the image file is decreased.

Abstract: What is disclosed is a novel system and method for color trapping on halftoned bi-level bitmaps. Color edges are detected and edge pixels that need to be trapped are identified. The number of pixels qualified as edge pixels eligible for color trapping can be up to a pre-determined number of pixels away from the color edge. Estimates for the continuous-tone values are obtained for the dominant colors on each side of the two-color edge. The contone value of the dominant color on the opposing side of the two-color edge is assigned to the qualified edge pixels. Qualified edge pixels are re-halftoned using their assigned contone value so that halftones for one color are extended beyond the edge into the other color. The re-halftoned edge pixels are combined with the original bitmap to produce a new bitmap for the image. The new bitmap is then provided to an image output device.

Abstract: The low and high occupancy rate matrix sets are stored in the inkjet printer which performs printing with dots having different sizes. For the original image where banding unevenness easily appears, used is the low occupancy rate matrix set where the occupancy rate of all dots is lower than 100% in the maximum value of gray level and the proportion of the large dots is high in a high range of gray level. For the original image where reproducibility of details is required, used is the high occupancy rate matrix set where the occupancy rate of all dots becomes 100% in a value of gray level lower than the maximum value of gray level and the proportion of the small dots is high in a middle range of gray level. It is therefore possible to perform appropriate printing in accordance with the classification of the original image.

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: Provided are printers and other electronic devices, systems, methods, and computer program products that automatically detect and determine UTF-16 encoding schemes and endiannesss thereof in an incoming XML data steam for XML declarations without a UTF-16 byte-order mark (BOM) or encoding declaration. This allows for the automatic and unambiguous accurate detection of UTF-16 encoded XML data within a mixed encoding environment, such as from multiple sources using more than one encoding scheme, even when XML data does not start with a BOM or encoding declaration.

Abstract: Embodiments provide a method comprising receiving a halftone image, the halftone image comprising a plurality of pixels, each pixel of the plurality of pixels including pixel data associated with a plurality of color planes; forming a pixel group, the pixel group including (i) a target pixel and (ii) one or more pixels that are neighboring to the target pixel; generating a pixel window for the pixel group; comparing the pixel window with a plurality of candidate patterns; determining that the pixel window matches with at least one of the plurality of candidate patterns; and based on determining that the pixel window matches with at least one of the plurality of candidate patterns, performing an image processing operation on the pixel group.

Abstract: The invention provides a printing method of printing on a printing medium. The method includes: generating dot data that represents state of dot formation at each print pixel of a print image to be formed on the printing medium by performing a halftone process on image data that represents an input tone value of each pixel making up an original image; and generating the print image by forming dots on each of the print pixels according to the dot data. The halftone process determines the state of dot formation by using a dither matrix that stores a plurality of threshold values, the plurality of threshold values being used for determining state of dot formation at each of print pixels of the print image to be formed on the printing medium according to an input tone value.

Abstract: A correction in less than one pixel raises an issue of generation of image defect such as density unevenness caused by a destruction of a screen pattern that generates a cycle of image data. To solve this issue, an image processing apparatus includes a correction unit configured to perform a correction less than one pixel on image data, and a changing processing unit configured to perform a correction by one pixel on image data, wherein the correction unit performs processing for correction in less than one pixel by shifting a pixel according to a moving locus synchronized with a cycle of the image data.

Abstract: An image processing apparatus comprises a dither processing device that applies dither processing to input image data to express halftone using line screens by increasing an area rate of the input image data and a controller that decreases the number of line screens and maintains a prescribed dropout width between the neighboring line screens when the area rate of the input image data increases and the dropout width falls below a prescribed level.

Abstract: What is disclosed is a novel system and method for minimizing dot visibility in color marking devices capable of dot-on-dot printing. The present method achieves minimum dot visibility for a given dispersed-dot screen by performing a CMYK to CMYKRGB conversion which uses less visible dots as much as possible before more visible dots are introduced. The output color dot coverages are calculated sequentially to minimize the coverage of more visible dots in a decreasing order of brightness. Resulting images have noticeably reduced halftone graininess, particularly in the mid to darker tone areas. The present method is also computationally efficient.

Abstract: A facsimile machine includes an image data generating unit that reads a original and generates image data, an information transmitting and receiving unit that transmits and receive the digital data, a first data generating unit that generates first digital data used for a real-time communication method without using analog data, and a second data generating unit that generates second digital data used for a deemed voice communication method without using analog data. when using the real-time communication method, the first data generating unit generates the first digital data and the information transmitting and receiving unit transmits the first digital data to the destination. When using the deemed voice communication method, the second data generating unit generates the second digital data and the information transmitting and receiving unit transmits the second digital data to the destination.

Abstract: A method detects weak or missing ink jets in an ink jet image generating system. The method includes generating a digital image of a test pattern of line segments in a process direction on an image receiving member with each line segment corresponding to one ink jet in a printhead, generating a response profile for a portion of the image receiving member on which the test pattern was generated, measuring the response profile, comparing the measurement of the response profile to a predetermined threshold, identifying missing and weak ink jets in response to the measurement of the response profile being less than the predetermined threshold, and moving the support member transversely across the process direction to a second position that enables each light sensor to image another portion of the image receiving member.

Abstract: An image processing apparatus, including a color conversion part configured to conduct a color conversion of image data. The color conversion part extends an information amount of an output value in the color conversion based on a first minimum information amount possible to depict a gradation in a lattice point interval of an input value in a look up table used for the color conversion.

Abstract: A plurality of types of positional shift postulated patterns are postulated wherein the positional shift of print head tips in a printer are postulated to have positional shift directions and distances. For each of the postulated positional shift postulated patterns, a base dithering mask is generated considering the ability to produce excellent dot dispersion characteristics when this postulated positional shift has occurred. Additionally, optimal dithering masks are generated through multiply combining the sets of threshold values that comprise the base dithering masks. Doing so enables the suppression of degradation of printed image quality, even when there are positional shifts between the print heads, in a half toning process for printing using a printer that is provided with a plurality of print heads that are arranged in a line across a printing range.

Abstract: A method and apparatus for dithering for multi-toning are provided. The apparatus includes a mask-pattern-generating unit that generates a mask pattern on R channel, G channel and B channel by selecting pattern values constituting the mask pattern on the channels based on randomly-determined seed values; a spatial-weight-determining unit that determines the weight for spatial dithering by using the pattern values and K-bit LSB data of the high-tone input image; and an output unit that outputs an M-bit image by applying the weight to M-bit input image data, exempting the K-bit LSB data, in a dithering apparatus for expressing an M+K bit high-tone input image in an M-bit low-tone output device.

Abstract: An image processing apparatus makes for making the halftone processing that can suppress a periodic pattern by periodically changing the correction amount while suppressing a dispersion in the area of each dot at a low computation cost.

Abstract: An image forming apparatus performs dither processing on image data to form an image subjected to pseudo-halftone processing. The image forming apparatus includes a dither processing unit that performs dither processing on image data, and a dither pattern generation unit that generates a dither matrix for use in the dither processing, in accordance with an output gradation level. The dither matrix has a size of M×N pixels, and has a plurality of halftone dots arranged in a predetermined pattern in accordance with the output gradation level in order to represent a gradation of each color. The plurality of halftone dots are arranged in the dither matrix such that the halftone dots corresponding to at least two colors are substantially identical in color area ratio to each other in the dither matrix irrespective of a relative position with respective to the colors.

Abstract: The invention aims to provide an image forming apparatus digitally correcting curve and inclination of a laser beam. To this end, provided is an image forming apparatus that corrects a position shift of a scan line in a sub-scanning direction.

Abstract: For a halftone representation of a grayscale data of an original image of P tones, an output resolution, a screen ruling frequency, and a screen angle are based to set a basic array of L×L pixels, where L is an integer greater than 1, and a number N of tones reproducible by the basic array is compared with P to generate a dither array using the basic array as its sub-array, such that numbers are assigned to pixels of sub-arrays by a prescribed rule, in order between the sub-arrays, starting from prescribed ones of centered and centermost pixels of the sub-arrays.

Abstract: A leak-prohibited image to be subjected to leak prohibition is comprised of dots DT so that two dots are included in an 8×8 matrix at a resolution of 600 dpi. The leak-prohibited image is formed as a computer terminal acquires image data, converts the image data to an image comprised of discrete microdots DT which cannot be resolved by copying, and outputs the converted image. Because the leak-prohibited image cannot be copied even if an image including the leak-prohibited image is copied, copy-originated information leak can be prohibited. Synthesizing a concealment image having a regularly discrete pattern with such a leak-prohibited image makes it difficult to view the leak-prohibited image from other directions than a front, thus prohibiting information leak by peeping.

Abstract: An information embedding apparatus (200) which embeds information in each character in an original document includes an extraction unit (202) which extracts the circumscribed rectangles of characters from the original document, a selection unit (203) which selects, based on a predetermined condition, a character in which information is to be embedded, from the characters included in the respective circumscribed rectangles, an information embedding unit (204) which embeds information in a character selected by the selection unit (203) as the character in which information is to be embedded, a character generation unit (205) which generates a character not selected by the selection unit (203) at a lower pixel density per unit area than that of the character in which the information embedding unit (204) embeds the information, and an output unit (206) which outputs the original document processed by the information embedding unit (204) and the character generation unit (205).

Abstract: A calibration data creating device includes a reference measured density memory, a dither data memory, a corresponding set density determining unit, a calibration data creating unit, and a calibration data creating unit. The reference measured density memory stores measured densities of reference density patches that are formed by an image-forming unit based on the reference density patch data. The dither data memory stores dither data that has a plurality of dot locations, the dither data having a prescribed threshold at each dot location. The corresponding set density determining unit determines corresponding set densities for the plurality of the reference set densities.

Abstract: In an image forming apparatus includes a quantization threshold value to convert input image data of an N value to output image data of an M value based on random dither processing. A flag to designate addition of a non-periodic component to a quantization threshold value can be set for each quantization threshold value and a threshold value that has a non-periodic component is added to the quantization threshold value based on a relation between a large and a small quantization threshold value in different threshold value levels with respect to any target pixel in the quantization threshold value.

Abstract: An image processing apparatus, including a color conversion part configured to conduct a color conversion of image data. The color conversion part extends an information amount of an output value in the color conversion based on a first minimum information amount possible to depict a gradation in a lattice point interval of an input value in a look up table used for the color conversion.

Abstract: This disclosure relates to decreasing the required buffer memory capacity while reducing the impact of an arithmetic error in error diffusion processing. A quantization circuit (4) quantizes input image data and outputs an output code. The quantization error generated in the quantization circuit (4) is calculated by an inverse quantization circuit (5) and subtracter (6). The calculated quantization error is stored in a buffer (8). Since the buffer (8) only needs to have a size capable of storing the quantization error, the size can be made smaller than before. A diffusion filter (9) diffuses the quantization error using a quantization error or the like, which is stored in the buffer (8). A latch (3) and bit connector (1) can usefully reduce the impact of an arithmetic error in error diffusion processing on the next input image data.

Abstract: Methods of the present invention allow for optimization of color and shades of gray documents prior to their conversion to a monochrome format. If color/gray elements are identified in the document, the distance between them and their intensity is determined. If there are elements with the same or similar intensity in close proximity to each other, colors of some of the elements may be replaced with solid monochrome colors, and/or dithered surfaces, and/or monochrome patterns. Further, the elements may be outlined. These improvements make elements in the document more distinguishable after its conversion to a monochrome format. The described color optimization and outlining may have wide applicability in the Internet Fax technology.

Abstract: A plurality of types of basic tiles are arranged in a matrix area while prohibiting an arrangement of only ON or OFF elements in two rows and two columns, to acquire an element matrix representing an arrangement of dots in a gray level of 50%. After one element is specified in each of a set of the ON elements and a set of the OFF elements, a process of specifying an element farthest from specified elements is repeated to acquire a turn-on order of dots with increase in gray level on a highlight side and a turn-off order of dots with decrease in gray level on a shadow side, and a threshold value of each element is determined in accordance with these orders. With this operation, it is possible to generate a threshold matrix which is capable of reducing graininess in an image generated by halftoning an original image.

Abstract: Methods of the present invention allow for optimization of color and shades of gray documents prior to their conversion to a monochrome format. If color/gray elements are identified in the document, the distance between them and their intensity is determined. If there are elements with the same or similar intensity in close proximity to each other, colors of some of the elements may be replaced with solid monochrome colors, and/or dithered surfaces, and/or monochrome patterns. Further, the elements may be outlined. These improvements make elements in the document more distinguishable after its conversion to a monochrome format. The described color optimization and outlining may have wide applicability in the Internet Fax technology.

Abstract: A method of printing a dithered image is provided which includes retrieving a planarized linear image from a memory, interpolating, with a processor, the resolution of said retrieved planarized linear image to an intermediate resolution in dependence of the color planes of said retrieved planarized linear image, interpolating, with the processor, the intermediate resolution to a print resolution, producing, with the processor, a dithered image in real-time from said interpolated image at the print resolution, and printing the dithered image using a printhead.

Abstract: A dither matrix generator includes: a main-cluster generator that generates at least one main-cluster in a matrix, the matrix including a plurality of cells, the main cluster area including a predetermined number of cells; a sparest searcher that searches a sparest area in the matrix, the sparest area being the area other than the area of main-cluster; a sub-cluster generator that generates at least one sub-cluster area, the sub-cluster area including a smaller number of cells than that of the main-cluster; a dither value allocator that allocates dither values to the plurality of cells of the matrix, the cells in the main-clusters having smaller dither values than those in the sub-cluster areas, the cells in the sub-cluster areas having smaller dither values than those in the areas other than the main-cluster and the sub-cluster areas.

Abstract: A method, apparatus and article of manufacture for modifying printing based upon direct on-the-fly media characteristic parameters is disclosed. The present invention on-the-fly directly measures a media characteristic parameter and performs real-time print modification in response thereto. The measured characteristic parameters include paper texture and composition, as well as adhesion and penetration of print. The modification of print in response to these measured parameters may allow a customer to maintain observed print quality with lower-cost materials. Adjustments may include the addition of coating, hot rolling, or adjustment of toner concentration. Measured parameters may include mottle, paper texture, and bleed through.

Abstract: A method for processing video data for display on a display device having a plurality of luminous elements comprising: applying a dithering function based on single ones of said luminous elements to at least part of said video data to refine the grey scale portrayal of video pictures of said video data, computing at least one motion vector from said video data, and changing at least one of the phase, amplitude, spatial resolution and temporal resolution of said dithering function in accordance with said at least one motion vector when applying the dithering function to said video data.

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 one aspect of the present invention, a method is provided for producing a halftone of a source image. The halftone includes halftone pixels. The halftone pixels are suitable for containing halftone dots. The method selects glyphs corresponding to intensities of regions (e.g., pixels) in the source image. The glyphs contain one or more halftone dots. The method locates halftone dots within the halftone pixels such that for at least one pair of halftone dots contained within a pair of halftone pixels sharing a common boundary, the halftone dots in the pair of halftone pixels extend in opposite directions from the common boundary.