Abstract: Provided is quantization processing that can reduce color development defect due to dot overlapping and can output an image with reduced granularity when the image is printed by using multiple kinds of colorants. To this end, dot arrangement information for a colorant for which dot arrangement is already determined among multiple kinds of colorants is acquired for a predetermined region of the image, and an evaluation value of each pixel included in the predetermined region is derived based on the arrangement information. In addition, for the predetermined region, a target value for a predetermined colorant for which dot arrangement is yet to be determined is derived based on the image. Then, whether or not to arrange a dot of the predetermined colorant in the predetermined region is determined based on the target value and the evaluation value.

Abstract: In an example, a method comprises receiving a first matrix of values to be mapped to a resistive memory array, wherein each value in the matrix is to be represented as a resistance of a resistive memory element. An outlying value may be identified in the first matrix. At least one value of a portion of the first matrix containing the outlying value may be substituted with at least one substitute value to form a substituted first matrix.

Abstract: Certain examples described herein relate to the embedding a pattern in an output content having at least two-dimensions, for example a printed output. Content data having at least two dimensions is processed to generate an array of spatial elements, each spatial element corresponding to a respective location in the output content and comprising a probabilistic distribution for a set of output material compositions. A threshold matrix is generated using pattern data corresponding to a pattern, and the array of spatial elements is halftoned using the threshold matrix. The threshold matrix is generated such that the pattern is embedded in the output content.

Abstract: A method of diffusing an error in three-dimensional contone model data includes generating halftone data for a slice among a number of slices of the three-dimensional contone model data, generating compensatory error values based on the generated halftone data, and adding the generated compensatory error values to contone data for a successive slice.

Abstract: A printing apparatus includes an input unit; a halftone processing unit; and a print unit. The halftone processing unit includes a comparison unit comparing one of a plurality of threshold values and a data gradation value, and an error diffusion unit generating dot data by comparing the data gradation value with an error diffusion threshold value. In a case where the data gradation value is less than the threshold value, the error diffusion threshold value is set to a high threshold value greater than a low threshold value. The high threshold value is set to a maximum value of the data gradation value or higher where the data gradation value is a predetermined value or higher, and to a value lower than the maximum value in a predetermined gradation range not less than the predetermined value.

Abstract: In the generation of a threshold matrix for Nx speed writing, first and second areas are set, the first area being a cluster of a plurality of first partial areas substantially evenly distributed in a matrix space, and the second area being an area of the matrix space excluding the first area. Next, at least two writing elements in each of the first partial areas are allocated occurrence numbers and changed into determined elements. Then, at least one writing element in the second area is allocated an occurrence number and changed into a determined element. Thereafter, the other writing elements are allocated occurrence numbers and changed into determined elements. In accordance with the occurrence numbers, the threshold value of each writing element is determined to obtain a threshold matrix for Nx speed writing. This results in a reduction in the graininess of an image in a highlight area.

Abstract: When a recording agent amount limiting process is carried out, a color reproduction range is narrowed, and therefore gradation properties of dark areas are deteriorated and information originally held by an image is sometimes undesirably lost. By obtaining (401) a colorant amount for each target pixel of input color image data, calculating (402) a colorant amount of a peripheral area of the target pixel, and correcting (400) a density range of the input color image data based on the colorant amount of the target pixel and the colorant amount of the peripheral area of the target pixel, amounts of recording agent are limited and reductions in image quality are prevented.

Abstract: An image processor includes a color conversion unit that generates color converted image data by converting color data and an error diffusion process performing unit that generates print data by performing an error diffusion process on the color converted image data. The error diffusion process performs a first error diffusion process on remaining data and performing a second error diffusion process on edge data such that an amount of ink used in the edge region by performing the second error diffusion process on the edge data is less than an amount of ink used in the edge region by performing first error diffusion process on the edge data.

Abstract: A method for detecting and growing isolated holes in a document image having a plurality of pixels is provided. The method includes isolating the pixels of the image to form a plurality of windows, each window having a target pixel; identifying a hole growth factor to grow an isolated hole in the received image; using the hole growth factor to identify tiered pixel patterns from a plurality of predefined, tiered pixel patterns, wherein each of the tiered pixel patterns having a predetermined hole growth factor; comparing the pixels within each window to the pixel patterns within the identified tier to identify a match between the pixels within the window and at least one of the pixel patterns; and changing a pixel value of the target pixel, when a match is identified, to grow the isolated hole by the hole growth factor.

Abstract: In a print control device, an executing unit executes an error diffusion process in which one of a first and second setting processes is executed. In the first setting process, the executing unit determines whether a first condition is satisfied. The first condition includes that the corrected value of the pixel data is larger than the first threshold value and that the first allowance condition determined by a first probability is satisfied. After the executing unit determines that the first condition is not satisfied, the executing unit determines whether a second condition is satisfied. The second condition includes that the corrected value of the pixel data is larger than the second threshold value. In the second setting process, the executing unit determines whether the second condition is satisfied. After the executing unit determines that the second condition is not satisfied, the executing unit determines whether the first condition is satisfied.

Abstract: The present disclosure relates to a method and system for processing isolated dots of an image to be printed by a printer. The method includes generating a random number, determining whether a target pixel is to be turned on and enabled for printing, determining a sum of pixels surrounding the target pixel in a plurality of pixels in a scanline of the image, the target pixel corresponding to an isolated dot in an input image, that are in an on state, the on state defined by a higher binary logic level relative to a binary logic level corresponding to a turned off pixel, determining a numerical value stored in a lookup table using the determined sum of pixels that are in the turned on state surrounding the target pixel as an index to the lookup table, and comparing the generated random number to the determined numerical value.

Abstract: In an error diffusion process, a random number acquiring unit acquires a random number included in a first random number range that depends on the gradation value of the target pixel data, in a case that the gradation value of the target pixel data is in a first range. The first correcting unit corrects the gradation value of the target pixel data into a first corrected gradation value by using the random number. The dot value setting unit sets a dot value of the target pixel data to either a first dot value or a second dot value. The first random number range corresponding to the gradation value smaller than the second threshold value includes a specific random number such that the first correcting unit corrects the gradation value into the first corrected gradation value greater than the second threshold value by using the specific random number.

Abstract: A method for detecting and growing isolated dots in a document image having a plurality of pixels is provided. The method includes isolating the pixels of the image to form a plurality of windows, each window having a target pixel; detecting an isolated dot in the received image; identifying a dot growth factor to grow the detected isolated dot in the received image; using the dot growth factor to identify tiered pixel patterns from a plurality of predefined, tiered pixel patterns, wherein each of the tiered pixel patterns having a predetermined dot growth factor; comparing the pixels within each window to the pixel patterns within the identified tier to identify a match between the pixels within the window and at least one of the pixel patterns; and changing a pixel value of the target pixel, when a match is identified, to grow the isolated dot by the dot growth factor.

Abstract: A method is disclosed. The method includes generating a Continuous Tone Image (CTI) with all pixel values same as a first gray level, generating an initial Half Tone Image (HTI) with all pixel values equal to minimum absorptance level and computing a change in pixel error for a first pixel. The change in pixel error is computed by identifying a first pixel indicated in a valid pixel map, toggling the first pixel with all the possible output states and swapping the first pixel with all neighbor pixels only if the stacking constraint is satisfied, updating the HTI with the maximum error decrease operation and continue to next pixel location till the end criteria is met.

Abstract: A method and system for generating a halftone image from an input image is disclosed. The method and system use error distribution and threshold perturbation that is based on the incoming tone value. A threshold bias table may be generated in real time for each incoming tone value. The values of the threshold bias tables are selected so that certain positions are forced to include a dot, in the case of light tone values, or not include a dot, in the case of dark tone values. A halftone process that uses threshold bias tables based on the incoming tone can reduce unnatural patterns in the image apparent to the casual observer, which results in a more pleasing image.

Abstract: In an image processing apparatus, fast error diffusion processing is performed without increasing the size of an error diffusion processing circuit, even in cases where the print data to be generated is 12 colors data or similarly large data. More specifically, with quantization by error diffusion, binarized image data for 12 colors is obtained by causing an image processing circuit that executes 6 colors quantization processing to operate twice. At this point, RAM realized by DRAM with comparatively slow operating speeds, for example, is accessed for error data diffused to a first raster and error data diffused from a last raster. In contrast, an error buffer realized by SRAM inside the image processing circuit with fast operating speeds is accessed for all other error data. Thus, as a result, memory access speeds for reading out and writing error data can be improved overall.

Abstract: The present disclosure relates to a method and system for processing isolated dots of an image to be printed by a printer. The method includes detecting whether pixels corresponding to an isolated dot in the image are in an on state. A first sum of pixels that are in an on state in a first pixel ring surrounding the pixels corresponding to the isolated dot when the pixels in the isolated dot are detected to be in the on state is determined. The first sum of pixels in the first pixel ring that are in the on state is compared with a first threshold sum. A first number of pixels in at least a second pixel ring either comprising of or surrounding the pixels corresponding to the isolated dot are turned on when the first sum of pixels in the on state is less than the first threshold sum.

Abstract: The present disclosure relates to a method and system for processing isolated holes in an image to be printed or displayed. The method includes detecting whether pixels corresponding to an isolated hole in the image are in an off state, determining a sum of pixels that are in an on state in a first pixel ring surrounding the pixels corresponding to the isolated hole when the one or more pixels in the isolated hole are detected to be in the off state, comparing the sum of pixels in the pixel ring that are in the on state with a threshold sum, turning off a number of pixels in at least another pixel ring either comprising of or surrounding the pixels when the first sum of pixels in the on state is greater than the threshold sum, and outputting the isolated hole including the turned off first number of pixels.

Abstract: A mutual optimization method for class matrix and diffusion weighting used in a halftone image processing technique and a mutual optimization system thereof are provided. In the method, a mutual optimization of a plurality of diffusion weightings and a class matrix used in a dot diffusion process is performed based on a concept of simulated annealing in order to avoid converging to local solution, so as to ensure an image quality of a halftone image generated by the dot diffusion process. Besides, since the mutual optimization method is for a hexagonal class matrix, a block effect appearing in the halftone image can be significantly reduced.

Abstract: The present disclosure relates to a method and system for processing isolated holes in an image to be printed or displayed. The method includes generating a random number lying in a finite range of numbers, determining whether a target pixel is to be turned off and enabled for printing as a hole, determining a sum of pixels surrounding a target pixel in a plurality of pixels in a scanline of the image, the target pixel corresponding to an isolated hole in an input image, that are in an on state, the on state defined by a higher binary logic level relative to a binary logic level corresponding to a turned off pixel, determining a numerical value stored in a lookup table in a memory unit coupled to the processor using the determined number of pixels that are in the turned on state surrounding the target pixel.

Abstract: An apparatus and a method are described for processing and reproducing a document including both text and half-tone images without generating undesirable image artifacts. A band-pass FIR filter with a predetermined frequency response is used to transform pixels in an input image to sharpen text edge and smooth pre-half-toned areas, and perform error diffusion and cluster dot screening methods on the transformed pixels. The FIR filter has unity gain at DC to preserve image brightness. An integrated error diffused cluster-dot screening approach is used to suppress moiré and other image artifacts, while providing a robust, crisp output.

Abstract: Error diffusion halftoning includes using a quantizer having an input and an output; and using a system having a bandpass characteristic to modify the quantizer input without feeding the quantizer output directly into the quantizer input. The error diffusion halftoning can produce clustered pixel halftone patterns that can be reliably reproduced by laser printers and other electro-photographic devices.

Abstract: An image processing apparatus quantizes multi-level image data of n colors, where n?2, by performing an error diffusion processing. The image processing apparatus includes: a dot arrangement determining unit that determines either one of an essential dot count and an essential recording material amount when the multi-level image data of n colors is converted into multi-level image data of m colors, where n>m?1, by the error diffusion processing; and a color arrangement determining unit that performs the error diffusion processing on each color component of the multi-level image data of n colors, calculates either one of a dot count and a recording material amount for each color component, and determines an arrangement of either one of the dot count and the recording material amount for each color component within a range of a corresponding one of the essential dot count and the essential recording material amount determined by the dot arrangement determining unit.

Abstract: A method for predicting an appearance of a rendering by a printer of a digital halftone representation of a continuous-tone image includes calculating a predicted absorptance value of a dot of a rendered halftone of the digital halftone representation. The dot corresponds to a pixel of the digital halftone representation. The predicted absorptance value is based on a configuration of pixel values of pixels in an immediate neighborhood of the pixel, and on a weighted contribution of a pixel value of each pixel in an outer neighborhood of the pixel. The method may be incorporated into a halftoning technique. Relating computer program product and data processing system are also disclosed.

Abstract: Systems and methods are described that facilitate compensating for slow scan direction displacement (e.g., skew and/or bow) defects in a raster line using slow-scan electronic registration. Input image data is buffered at low-resolution (e.g., 600 spi or the like). Displacement compensation is performed as the low-resolution contone image data is converted to high-resolution (e.g., 2400 spi or the like), and a displaced (e.g., staggered) halftoning threshold array is indexed to account for detected displacement. Displacement compensation is again performed during conversion of the high-resolution contone image data to high-resolution binary image data that is used to generate an output image.

Abstract: A method and system for processing image data in an image processing device for a plurality of pixel positions within a plurality of scanlines. The method and system includes storing a starting stamp value and a plurality of delta stamp values for the scanline. The stored values being used to generate a pixel stamp value for an input pixel in the scanline, by adding a starting value or previous pixel stamp value and the stored delta stamp value for the input pixel. Further includes receiving an input pixel intensity value for the input pixel and determining an output pixel intensity value. Subsequently, if the output pixel intensity value for the input pixel is equal to a value for a dot or hole the delta stamp values for at least one pixel having a location previous or subsequent to the input pixel can be updated.

Abstract: An image processing method, for correcting a blur a due to an optical system of an image capturing apparatus, the image processing method including, storing a plurality of representative filters in a memory, selecting a subset of representative filters from the plurality of representative filters based on a pixel position of a pixel of interest in an image, applying each of the selected representative filter to a pixel value of the pixel of interest, and correcting the pixel value of the pixel of interest based on (a) a result of the application of filters, and (b) the pixel position of the pixel of interest.

Abstract: An image processing apparatus which may include a grayscale modulator forming a ?? modulator. The modulator may include an adder that adds the pixel value of an image and an output of a feedback arithmetic unit, a quantizing unit that quantizes an output of the adder and outputs a quantized value including a quantization error as the result of ?? modulation, a subtractor that calculates the quantization error, and the feedback arithmetic unit that filters the quantization error and outputs the filtering result to the adder. The filter coefficient of filtering by the feedback arithmetic unit may be determined such that the amplitude characteristics of noise shaping by the ?? modulator in a frequency band that is equal to or more than an intermediate frequency band are the inverse characteristics of the spatial frequency characteristics of the human eye.

Abstract: This presents an image processing apparatus and an image processing method which print and output image data subjected to halftone processing with an appropriate density characteristic. The image processing apparatus generates a halftone image from a multi-value image using a threshold value arrangement, and generates a difference image between the generated halftone image and a second halftone image having the density characteristic different from that of the generated halftone image. The image processing apparatus stores the generated halftone image and the generated difference image.

Abstract: An error diffusion processing method and apparatus quantizes an input grayscale value of a pixel (m, n) of an input image based on a determination of whether the input grayscale value belongs to one of ranges divided by a plurality of thresholds. The ranges include at least one shadow area which is darker than a median grayscale value, and the input grayscale value is quantized to a predetermined grayscale value which is brighter than the median grayscale value in a predetermined method and thereby a binary grayscale value of the pixel (m, n) is determined. The error diffusion processing method and apparatus obtains an error from the input grayscale value and the binary grayscale value of the pixel (m, n), and distributes the error to neighboring pixels of the pixel (m, n) according to a predetermined error diffusion coefficient and modifies input grayscale values of the neighboring pixels.

Abstract: Embodiments of the present invention provide techniques and configurations for error diffusion halftoning of an image including receiving a signal that indicates selection of a first implementation or a second implementation of determining a threshold perturbation value for error diffusion halftoning of an image, and determining the threshold perturbation value using a table of programmable values according to the selected one of the first implementation or the second implementation, wherein the second implementation provides fewer threshold perturbation values for a larger region of the image than the first implementation. Other embodiments may be described and/or claimed.

Abstract: It is determined whether the pixel of interest in image data to be processed belongs to area 1 not close to a scan line changing point where a scan line changing process is done (S101). If the pixel of interest belongs to area 1, an error diffusion process is performed using an error diffusion matrix for area 1 (S102). If the pixel of interest belongs to area 2 close to the scan line changing point, the error diffusion process is performing using an error diffusion matrix for downward scan line changing for area 2 when the scan line changing process is changing to a lower line, or an error diffusion matrix for upward scan line changing for area 2 when the scan line changing process is changing to an upper line.

Abstract: An image processing apparatus 101 that generates output image data based on multi-level image data is provided with an error diffusion processing unit 104 that generates tone pixel data from the pixel-of-interest data according to an error diffusion method, a dither processing unit 103 that generates tone pixel data from the pixel-of-interest data according to a dither processing method, an allotment ratio determination unit 105 that increases the allotment ratio with respect to the error diffusion method as the difference between the maximum density and the minimum density increases, and a composition unit 109 that composites the tone pixel data for a pixel of interest that has been generated by the error diffusion processing unit 104 and the dither processing unit 103 according to the allotment ratios determined by the allotment ratio determination unit 105, and outputs the composited data as pixel data of the output image data.

Abstract: When multi-pass printing is performed, the dot overlap rate (ratio of the number of dots that overlap and are to be printed in the same pixel area by the plurality of relative movements with respect to the total number of dots to be printed in a pixel area by the plurality of relative movements) in pixel areas having medium-density where density unevenness caused by density fluctuation easily stands out is made higher than the dot overlap rate in pixel areas having low-density and pixel areas having high-density. By doing so density unevenness caused by density fluctuation is suppressed. In addition, the dot overlap rate in pixel areas having low-density and pixel areas having high-density is low, so it is possible to reduce graininess in low-density areas and suppress a decrease in density in high-density areas.

Abstract: A halftone image generation method used in a system including an image input module and a halftoning processing module for generating a halftone image is disclosed. First, an original image is received by the image input module and a dot diffusion process is performed to the original image to generate the halftone image using a first class matrix with a first size and a corresponding first diffused weighting matrix with a first diffused area size, wherein the first class matrix indicates a processing order of the dot diffusion process and the first class matrix with the first size, the first diffused area size and the corresponding first diffused weighting matrix with the first diffused area size are optimized results determined in advance by the halftoning processing module according to class matrixes of different sizes and diffused areas of different sizes.

Abstract: A quantizing unit, error detector, error diffusion matrix, and adder quantize a pixel of interest of an input image by an error diffusion method. A calculation unit and gain adjuster calculate a value to be added to the pixel of interest with reference to quantized pixels. The adder adds the calculated value to the pixel of interest. A control unit controls the calculation of the gain adjuster.

Abstract: An image forming apparatus includes a tone correction storage unit that stores a plurality of tone correction charts for correcting tone of image data; a determination unit that determines characteristics of the image data; a selection unit that selects a tone correction chart suitable for the image data from the plurality of tone correction charts stored in the tone correction storage unit; a chart print unit that prints the tone correction chart selected by the selection unit on a sheet; a receiving unit that receives an adjustment value inputted based on the tone correction chart printed by the chart print unit; a tone correction unit that corrects tone of the image data based the adjustment value; and a print unit that prints out the image data after correcting tone of the image data.

Abstract: The present invention relates to a method and apparatus capable of generating frequency-modulation halftone dots in high speed and belongs to the field of the digital image halftone. In the prior art, read-write operation is usually carried out many times in error rows during processing each pixel so that halftone dots are generated in low speed. In the method according to the present invention, the error generated by the current pixel is buffered in a register file and the final accumulated error values are written in the error rows only after all of the relative pixels are processed. Thus, read-write operation is carried out only once in the error rows for processing each pixel. The present invention also provides an apparatus to implement the method. The apparatus comprises an error row memory, an error buffer register file, a gray generation circuit, a threshold comparison circuit, an error generation circuit, an error buffer register file control circuit, and an error row control circuit.

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: Image data of a pixel of interest is inputted, diffusion data diffused from errors occurred by decrease of a tonal number of image data is added to the image data of the pixel of interest, the tonal number of the image data of the pixel of interest, to which the diffusion data has been added, is decreased using an error diffusion method or minimized average error method, and an error occurred in the decrease of the tonal number for the pixel of interest is diffused to pixels close to the pixel of interest. Further, the errors occurred by the decrease of the tonal number of the image data in a predetermined image region are integrated as an integrated error, and a threshold value used in the error diffusion method or minimized average error method is set based on the image data of the pixel of interest and the integrated error.

Abstract: A method and apparatus for processing an image are provided that can suppress blur edges at an edge portion of a character so that sharpness and quality of the image can be improved. The apparatus comprises an inside and outside edge discrimination portion for discriminating whether a target pixel to be processed belongs to an inside edge or to an outside edge, a threshold value generating portion for selecting a threshold value from plural threshold values for error diffusion process in accordance with an area discriminated by the inside and outside edge discrimination portion to output the selected threshold value and an error diffusion process portion for performing the error diffusion process for multilevel input data concerning the target pixel by utilizing the threshold value generated by the threshold value generating portion so as to produce output data whose gradation steps are reduced.

Abstract: Density-correction-table lists showing an amount of density changes in respective density levels of images that exist after an image having a predetermined density has been printed on a predetermined number of sheets are maintained. The amount of density changes in the respective density levels for an image ratio that exists after the predetermined number of sheets have been printed on and for the predetermined number of sheets that have been printed on are obtained with reference to values in the maintained density-correction-table lists. A density correction characteristic is determined using the obtained amount of density changes.

Abstract: A technique for performing high-quality cluster type FM halftone image output without “anisotropy” or “sweep out texture” phenomenon is provided. An error diffused to a current pixel position and a random number RND are added by an adder to multi-level pixel data as a subject of binarization, and supplied as pixel data Pxy to a selector. The selector compares the pixel data Pxy with thresholds, and supplies the pixel data Pxy to one of a highlight portion processor, a dark portion processor and an intermediate portion processor. The highlight and dark portion processors refer to already-binarized results within a range determined in accordance with the value of the input pixel data Pxy, and determine a binarization result Qxy. The intermediate portion processor compares a threshold, which monotonously increases in accordance with the value of the pixel data Pxy, with the pixel data Pxy, thereby determines the binarization result Qxy.

Abstract: Machine-enabled methods of, and system, and processor readable media, embodiments for, tone quantization error diffusion comprising a first stage process and a second stage process. where pre-calibrated index tables may be applied by which quantized pixels may be expressed according to halftones.

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: Diffusion dithering can be performed efficiently by applying a set of diffusion filter weights with one or more shift, add, and/or subtract operations. An existing diffusion filter can be approximated with dyadic rationals, thereby allowing division operations in applying the filter weights to be performed with bit-shifting operations. An algorithm is identified to calculate the product of a set of filter weights and a pixel error, where the algorithm performs the calculations using one or more shift, add, or subtract operations. An exhaustive search of the combinations of operations can be made to find an efficient algorithm to calculate the products.

Abstract: One aspect of the method/apparatus finds, for each input-image pixel, an “offset weighted average” of neighboring-pixel interactions—and uses the averages to make a final image. Another aspect assumes a value for each pixel, to use in a final rendered image form—and, at each in a series of approximations, determines whether to change the value, and finds a probabilistic weight to help determine. Yet another finds, for each pixel, a numerical representation of neighboring-pixel interactions—and establishes a distance cutoff for use in defining “neighbor”, and uses the representation to decide whether to change color values. Still another finds a desired or ideal number of print passes, and adapts the number of passes actually used to the found number. Another combines halftoning and printmasking into one procedure and prints images prepared thereby. Another integrates halftoning and image filtering, to obtain esthetic visual effects, into one procedure—and prints images thus prepared.

Abstract: An image processing apparatus includes a dividing portion that divides input multivalue image data into a plurality of bands, an error diffusion process portion that carries out an error diffusion process on each divided band to quantize each pixel, and a controlling portion that controls the dividing portion and error diffusion process portion. The error diffusion process portion, following control by the controlling portion, operates in a first mode to repeat the error diffusion process not accompanying quantization given times on each noted pixel included in a given line of the each band (head line, etc.), and operates in a second mode to carry out the error diffusion process on the each band sequentially from the head line of the each band on the basis of an error value obtained in the first mode to put out quantized data.

Abstract: Quantizing means generates a quantized density and a quantization error component for a target pixel in a plurality of pixels. A subtracter calculates, for the target pixel, a quantization error correction component by subtracting the density of the target pixel contained in preliminary ejection data from the quantization error component output from the quantizing means. An allocator allocates the quantization error correction component calculated by the subtracter to a plurality of the pixels around the target pixel. The quantizing means outputs the quantized density and the quantization error component of the target pixel by performing an addition using the density of the target pixel contained in the image data, the density of the target pixel contained in the preliminary ejection data, and the accumulated diffused error component assigned to the target pixel by the allocator when other pixels are quantized.

Abstract: A quantizing unit, error detector, error diffusion matrix, and adder quantize a pixel of interest of an input image by an error diffusion method. A calculation unit and gain adjuster calculate a value to be added to the pixel of interest with reference to quantized pixels. The adder adds the calculated value to the pixel of interest. A control unit controls the calculation of the gain adjuster.