Abstract: An image-processing apparatus for quantizing multi-level (M-level) image data into N-level values, where M>N>1, using a multi-level error-diffusion process or a minimum-average multi-level error method is disclosed. The image-processing apparatus includes: means for outputting correction data; means for setting a quantization-threshold value; means for comparing the correction data and the quantization-threshold value so as to output N-level image data; and means for calculating an error generated with generating the N-level image data.

Abstract: A plurality of items of color-component data representing an image are input and a plurality of items of output color-component data representing an image to be reproduced by a printer are decided and output. In the case of an image in a specific area in which an entered image is represented by at least two items of color-component data, any one item of color-component data is decided upon as output color-component data.

Abstract: An image processing method of quantizing multi-tone image data by an error diffusion method, includes the steps of a) detecting change of the image data; and b) oscillating cyclically in image space a threshold for the quantization in an oscillation range controlled according to the detection result of the step a).

Abstract: Embodiments include a method for halftoning a source image. The halftoning includes error diffusion processing of a first separation of plural color separations of a pre-rendered image after error diffusion processing a second separation of the plural color separations of the pre-rendered image. The error diffusion processing of the first separation including, for respective pixel values corresponding to the first separation, choosing respective magnitudes of the respective pixel values as a function of the error diffusion processing of the second separation. A rendered image is output which comprises the same plural color separations. The output rendered image is populated with, for the first separation, pixel information based on the respective magnitudes.

Abstract: A printing control method of generating dot data representing a state of dot formation at each pixel in a printed image represented by an given image data, by formation of dots in respective pixels with the at least one colored ink and the quality-enhancing ink available in the print unit. This process includes a processing mode configured to make a quality-enhancing ink dot-recording rate for pixels belonging to a peripheral area lower than the quality-enhancing ink dot-recording rate for pixels belonging to a center area.

Abstract: A device including: an acquirer acquiring image data having an M-value (M?3) pixel value; a memory storing nozzle information; another memory storing error diffusion matrices having different diffusion ratios of an error; a selector selecting specific pixel data in the image data; an N-value converter converting the M-value to an N value (M>N?2); a diffuser diffusing the error to pixel data not subjected to the conversion in the image data according to the error diffusion matrix by using a difference between a selected pixel data value before and after conversion as the error; a generator generating print data defining nozzle dot information corresponding to the image data after the conversion; and a printer. The diffuser selects a specific error diffusion matrix for each selected pixel data according to the nozzle information, and diffuses the error to the pixel data not subjected to the conversion.

Abstract: A method for multi-toning an input digital image having input pixels with two or more color channels to form an output digital image having modified output levels. The method includes producing shifted error signals for each color channel, weighting the shifted error signals to determine weighted error signals for nearby pixels that have yet to be processed; producing shifted weighted error signals; and adjusting the input levels for the nearby pixels responsive to the shifted weighted error signals.

Abstract: An image forming device includes a quantization unit which quantizes each pixel of an M-level gradation input image into one of N levels (M>N?2) through an error diffusion process. An operation unit performs a predetermined operation according to a position of a target pixel to a gradation value of the target pixel before quantization when the gradation value of the target pixel is equal to a specific concentration.

Abstract: An image forming apparatus, for forming an image with using distributions of two or more types of dots having different densities per unit area in a same hue, including: a threshold value matrix; and a dot formation determining section for carrying out comparison between a pixel value at a target pixel in the input image and a threshold value corresponding to the target pixel in the threshold value matrix, and for determining, whether to form or not to form any one of the two or more types of dots, wherein threshold values in the threshold value matrix are configured so that a frequency of dot formation is lower, for gradation regions in which a dot density of any of the two or more types of dots is low and/or high, than that for gradation regions in which the dot density is in average level.

Abstract: Image processing apparatus and image processing method for formation of high quality image by high-speed error diffusion processing by execution of more complicated threshold condition processing in a simple manner. When error diffusion processing is performed on multivalued image data having plural density components and the result of processing is outputted, upon execution of error diffusion processing on a first density component among the plural density components, a threshold value used in the error diffusion processing is determined based on a density value of a second density component, then the error diffusion processing is performed on the first density component based on the determined threshold value, and the result of execution of the error diffusion processing is outputted.

Abstract: When a three-dimensional image viewed stereoscopically by superposition of a lenticular sheet is merely binarized and output, fringes are produced in the direction in which cylindrical lens elements repeat on the lenticular sheet, and therefore an appropriate stereoscopic image is not observed. Accordingly, a multiple viewpoint image sequence of the image of a subject is acquired, a three-dimensional stripe image is synthesized by the images of the image sequence, the stripe image is converted to a multivalued image by reducing the number of tones by the error diffusion method, the multivalued image is convened to a binary dot pattern by the density pattern method, and the dot pattern is formed on a recording medium.

Abstract: If a false edge will possibly occur at a portion in an image where the input pixel value. Iin is equal to the value (Rj+F), where j=N, S, M, or L, the noise value N is generated when the input pixel value Iin is around the value (Rj+F). The noise value N has a value equal to a product of a random number, the value “rate”, and the value “coefficient”. The value “rate” becomes the maximum value (1) when the input pixel value Iin is equal to the value (Rj+F), and becomes zero (0) when the input pixel value Iin is smaller than or equal to the value (Rj+F)?Range and when the input pixel value Iin is greater than or equal to the value (Rj+F)+Range.

Abstract: A halftone reproduction processing section (29) of an image processing apparatus (13) has a control part that conducts a halftone processing of input image data by subjecting it to an error diffusion processing, selects input image data on at most one, namely, one or no input image data from the input image data on at least seven colors, namely, primary colors of cyan, magenta, and yellow used as visible colors for forming an image on a recording medium, secondary colors of red, green, and blue that are the complementary colors of the visible colors, and black, and subjects the input image data on the other colors to a different error diffusion processing.

Abstract: A method and system for performing error diffusion are disclosed. An ordered set of pixels, including a pixel intensity value for each pixel, is received. Each pixel intensity value includes a value within a range from a low value to a high value, inclusive. An initial error value is also received. Based on the pixel intensity values and the initial error value, a pixel value for each pixel and an updated error value are computed substantially simultaneously with each other.

Abstract: An algorithm for modulating printer half-tone screening based on the tonal values of the region being reproduced is provided. The algorithm determines the tonal values for a particular region and assigns real number constants to that region. As the clustering screen is applied, the threshold values in the clustering screen are reduced (divided) by the real number constants thereby modulating the effect of the application of the clustering screen. For deep tonal regions, the clustering screen is applied at full strength, while in light tonal regions no clustering effect is applied. The algorithm results in a an image that has a greater dynamic range without the appearance of stair stepping while eliminating clustering artifacts from the lighter regions.

Abstract: For image processing for repeatedly executing process segment sets including N (N is an integer of 3 or greater) unit process segments Lc, Lm, Ly, Lk, Llc, Llm and Ldy, unit process segments are executed by M (M is an integer of 2 or greater but less than N) processing units. The unit process segments include a first-type unit process segments Lc, Llc, Llm, and Lk for performing processing using a first processing method and a second-type unit process segment Lm, Ly and Ldy for performing processing using a second processing method that is different from the first processing method. Then, when executing process segment sets, the M unit process segments including at least one each of the first-type and the second-type unit process segments Lc, Lm are first executed on the M processing units.

Abstract: When the input value becomes close to the medium dot relative density value (Den_M), the large dot threshold value (Thre_L) and medium dot threshold value (Thre_M) become close to each other. It is possible to prevent output values from being converged to the particular medium-dot output value. When the input value becomes close to the small dot relative density value (Den_S), the medium dot threshold value (Thre_M) and the small dot relative density value (Den_S) become close to each other. It is possible to prevent output values from being converged to the particular small-dot output value.

Abstract: An image processing apparatus includes a correction data generation section, a binarization section, an edge pixel setting section, and a selection section. The correction data generation section generates correction data. The binarization section binarizes one of the correction data generated and contone image data that has been subjected to the one of color correction and density correction, to generate corrected binary data. The edge pixel setting section sets a pixel, in binary image data, assumed to be an edge as an edge pixel. The selection section selects, for the pixel set as the edge pixel, the corrected binary data and selects, for a pixel not being set as the edge pixel, the binary image data. The edge pixel setting section detects presence of the edge from the binary image data.

Abstract: For image processes performed repeatedly using a plurality of processing units on a plurality of partial images aligned mutually adjacent to each other, specified processing is performed. This image process includes (i) a first-type process segment on first partial image data representing a partial image to generate M types (M is an integer of 2 or greater) of second partial image data; and (ii) the respectively corresponding M types of second-type process segments on the M types of second partial image data. When executing image processing, parallel processing is performed for the second-type process segment relating to the i-th (i is a positive integer) partial image and the first-type process segment relating to any of the (i+1)-th to the (i+p)-th (p is a positive integer) partial images.

Abstract: An error diffusion method and system to ameliorate the effects of data quantization. The error diffusion method is especially well-suited to display systems that process groups of pixels in a given row (318) simultaneously. Errors generated when processing pixels in one row (318) of a first group (314) cannot be propagated to other pixels in the same row (318) of the same group (314) since the other pixels are processed by the time the error signal is available. The method and system pass errors from most of the pixels (302) in the group (314) to pixels below and to the right in the next row (320) of the same group (314). Errors from the last pixel (304) in the group (314) are passed to the pixel (308) in the following row (320) beneath the last pixel (304) and to the first pixel (310) in the next group (316) of pixels in the same row (318). To avoid creation of structured visual patterns, a white noise signal is added to the error signals.

Abstract: An improved digital halftoning method that uses an input image's global gray levels to determine the local gray levels of a monochrome output image. Input multi-bit pixels grouped into two-pixel-by-two-pixel local subcells are variously aggregated into one or more larger supercells. The size of said supercell(s) is related to and limited by the size of the global input bitmap. A final monochrome gray level is derived from said supercell(s) and distributed within contained subcells. Subcell gray levels are expressed as interim whole monochrome pixels and gray level remainders. A comparison is made of the final supercell and the summed interim subcell monochrome gray levels. An ordering of the remainders is used for assignment of additional monochrome pixels, if necessary, to yield final subcell monochrome gray levels. Gray level rounding errors thus are quantized by reverse diffusion until a monochrome gray level for each of the global image's two-pixel-by-two-pixel local subcells is derived.

Abstract: An error utilization factor line, indicative of a relationship between the amount of the error utilization factor K and input data for a present pixel, is determined dependently on characteristics of the image, on the value of the threshold, on the size of the distribution matrix, or on the condition of the recording operation. The amount of the error utilization factor K is determined dependently on the input data of the present pixel and based on the error utilization factor line. The correction amount F, collected from the already-processed nearby pixel, is multiplied by the error utilization factor K, before being added to the input data of the present pixel for the halftone process.

Abstract: Provided are a method and apparatus for determining error diffusion coefficients.

Abstract: A device and method is provided for breaking up undesirable patterns in vector error diffusion when the sum of inputs is near fraction values of the total input range. In the method, the value of the sum is calculated modulo the maximum input value. The mod value tendency to produce limit cycles is then determined for multiple planes in a manner similar to that for an individual plane. The threshold process for the vector calculation can then be modified to break up the cycles that occur in the combinations of the multiple colors. Typically, the largest of the individual plane modifications and the vector sum mod value is used for threshold modification. At least two different types of threshold modifications are possible: (1) random or psuedo-random noise address to the threshold; and (2) non-contiguous regions of threshold.

Abstract: A method for processing image data that employs a stamp field that contains data representing a distance metric for use with a variety of error diffusion operations. The distance metric possesses distance-order preservation permitting the distance from a previous dot to be determined by incrementing the distance metric, without knowing precisely where the previous dot was printed.

Abstract: Artifacts of error diffusion halftoning are reduced by selecting a halftone threshold for a current pixel on the basis of an accumulated halftone error for the pixel and its neighbors.

Abstract: The image processing apparatus or the printing device of the present invention forms units by grouping adjacent multiple-pixels and converts the image data to the dot data representing dot on/off state for each of pixels. The apparatus stores the dot data in a condition enabling identification of the dot on/off state for at least one of pixels within the previously converted units. When the apparatus converts the image data to the dot data by a unit, The apparatus serially specifies a interested pixel, within a unit to be converted to the dot data, for determination of dot on/off state. Then the apparatus determines the dot on/off state for the interested pixel, according to a characteristic that controls the proportion of a number of dots formed at the predetermined location of the unit against a number of all dots into a predetermined range. It prevents cyclical patterns from becoming visible and degrading image quality.

Abstract: A method for multi-level halftoning an input digital image to form an output digital image which includes a multi-level error diffusion halftoning process incorporating periodic dither signals whose amplitudes are adjusted as a function of the error-diffusion texture characteristics.

Abstract: A method for multi-toning an input digital image having input pixels with two or more color channels to form an output digital image having modified output levels. The method includes producing an error signal for each color channel, combining the error signals to produce a combined error signal, sorting the error signals to produce a set of sorted error signals, and determining modified output levels responsive to the set of sorted error signals and the combined error signal.

Abstract: An apparatus includes a first processing device to perform halftoning on a first set of values corresponding to a first set of pixels and a second processing device to perform halftoning on a second set of values corresponding to a second set of pixels, with ones of the first set of pixels located adjacent to the second set of pixels and with ones of the second set of pixels located adjacent to the first set of pixels. The apparatus further includes a bus arranged for transferring a third set of values, from the halftoning of ones of the first set of values corresponding to the ones of the first set of pixels, to the second processing device and for transferring a fourth set of values, from the halftoning of ones of second set of values corresponding to the ones of the second set of pixels, to the first processing device.

Abstract: An error diffusion processing circuit includes an error diffusion processing unit and a noise signal unit. The error diffusion processing unit generates a first output image signal of a first pixel by carrying out an error diffusion process, based on an inputted first input image signal of the first pixel. The number of gray tones of the first output image signal is smaller than that of the input image signal. The noise signal unit which generates a noise signal and outputs the noise signal to the error diffusion processing unit. The noise signal is inputted into a feedback loop of the error diffusion process.

Abstract: An error diffusion method applied to halftone processing for image data. The image data comprise a plurality of pixels. The method comprising the steps of dividing the image data into a plurality of image blocks; selecting one of the pixels belonging to each of the image blocks as a target pixel, wherein the target pixel is located on the boundary of the corresponding image block; assigning a predicted error to the target pixel; and executing the error diffusion method on the rest of the pixels of the image blocks according to the predicted error of the target pixels of the image blocks. When the error diffusion is performed, target pixels are found in the image block and then predicted errors are assigned to the target pixels in order to calculate their output values. The target pixels are located at boundaries of the image blocks, and the predicted errors may be 0 or the transversal or longitudinal errors outputted from the pixels above the target pixels.

Abstract: A method of embedding an image into two images by performing a digital halftoning process on a Cartesian product of color spaces to embed the image into the two images. A digital halftoning process includes an iterative isotropic halftoning process. The iterative isotropic halftoning process for each iteration if Outimage has not changed between two iterations or maximum number of iterations reached, then exit the iterations loop.

Abstract: The present invention relates to error diffusion logic in which three partial diffusion error values are produced in a pipelined manner and then summed together when the last partial error value is produced. The resulting summed error can be used to adjust a target pixel in a sequence of pixels or stored in a buffer until further corresponding partial error is produced for adjusting the target pixel.

Abstract: A method for halftoning includes the steps of defining a first set of weight sets, and defining a second set of weight sets. A first error associated with a first pixel location of a plurality of pixel locations is diffused to a first neighboring at least one pixel location using a first weight set selected from the first set of weight sets, and a second error associated with a second pixel location of said plurality of pixel locations is diffused to a second neighboring at least one pixel location using a second weight set selected from the second set of weight sets. The first diffusing step and the second diffusing step are alternately performed along each scanline in the image to reduce visual artifacts.

Abstract: A method for processing image data that employs a stamp field that contains data representing a distance metric for use with a variety of error diffusion operations. The distance metric possesses distance-order preservation permitting the distance from a previous dot to be determined by incrementing the distance metric, without knowing precisely where the previous dot was printed.

Abstract: There is provided an image processing apparatus which enables high-speed processing with simplified multiplications and divisions even in the case of error diffusion comprised of a combination of processes of two or more colors. The image processing apparatus performs error diffusion on multivalued image data composed of a plurality of density components and outputs the result of the error diffusion. A plurality of error tables are stored in a storage device. One error table is selected from the plurality of error tables according to a density value of a first density component among the plurality of density components and a density value of at least one other density component when performing the error diffusion on the first density component. A CPU performs the error diffusion on the multivalued image data using the selected error table.

Abstract: It is an object of this invention to provide a ternary or higher-order quantization method which avoids close gathering of pixels at a first output level. First and second threshold values Lth1 and Lth2 for ternarization and output values 0 (blank), 1, and 2 as converted output values are set to have a relationship of output value of 0 (blank)<first threshold value Lth1<second threshold value Lth2<output value of 1<output value of 2. This prevents a quantization error from becoming 0 when an input pixel value is an intermediate value, and prevents continuous outputting of only pixels having the output value of 1. When this image is printed, small ink dots corresponding to the output value of 1 are not easily continuously printed. This improves the image quality.

Abstract: A method for processing color image data to generate multi-level image data with arbitrary output levels and arbitrary level spacing. The method identifies a gray level spacing for each of a first and second color separation pixels and scales the gray level for each of the first and color separation pixels scaled to a common level spacing in relation to their corresponding gray level spacing. The scaled gray levels are then be thresholded to one of the two multi-level output values corresponding to the bounds of the gray level spacing.

Abstract: A method of processing image data when generating multi-level data having arbitrary levels with arbitrary level spacing. The method scales the value of the input pixel to a common level spacing in relation to the arbitrary level spacing in which the input pixel resides. The scaled input data is then treated and processed in the same manner as processing image data with a binary output. The same processing functions, operations and values can be readily applied to data within each level without regard to the level spacing or output levels.

Abstract: A method and apparatus for performing error diffusion of a multiresolutional representation of an image is disclosed herein. In one embodiment, an image is received as a pixel representation. The image is converted from a pixel representation to a multiresolutional representation having multiresolutional coefficients. Each multiresolutional coefficient is quantized and an error is passed to one or more other multiresolutional coefficients as specified by an error filter. Finally, the resulting quantized image is produced as output.

Abstract: The invention is a method for printing a color proof from an initial halftone bitmap file (10) having individual dots (10a, 10b, 10c, 10d) using a spatial filter (20) which is created from a calibration curve (30) for a printing press (380). The method further consists of sending an initial halftone bitmap file consisting of individual dots to the spatial filter creating a filtered output (40), quantizing the filtered output from the spatial filter to “n” levels to create a quantized image (50), transmitting the quantized image to a color printer (70), and printing a halftone color proof (80) on the color printer.

Abstract: There has been a demand to accelerate image data conversion through the use of the error diffusion method. To convert image data, it is determined whether a specified block process condition is satisfied on the basis of a gradation value for each pixel in a target block. When the block process condition is true, a process is performed to diffuse a gradation error for the entire target block and convert image data for pixels in the target block at a time. Even when the block process condition is false, it is determined whether to form a dot in the target block. When it is determined that no dot should be formed, a process is performed to diffuse a gradation error for the entire target block to the unconverted pixels in another block and convert image data for pixels in the target block.

Abstract: An image processing apparatus processes multivalued color image data that includes a plurality of color components. The apparatus includes an adding unit to add per-color-component quantization error values from a neighboring pixel to respective ones of a plurality of color components included in a pixel of interest, and a quantization unit to correlate a sum of the values of each of the color components to which the error value has been added by the adding unit to a sum of values after conversion, and deciding the value of each color component after conversion upon distributing the sum of pixel values after the conversion in accordance with the ratio of each of the color components before conversion. In addition, a coefficient decision unit decides diffusion coefficients, which diffuse quantization error to neighboring pixels, based upon the value of each of the plurality of color components included in the pixel of interest.

Abstract: There is described a compound apparatus, having a plurality of outputting functions including at least a copy function. The compound apparatus includes: an image-reading device to read an original image residing on a document so as to convert the original image into image data; a binary-coded image data generating section to generate binary-coded image data by applying a binary-coding processing to the image data; an image-data storing section to store the image data or the binary-coded image data; a designating section to designate an outputting function among the plurality of outputting functions; a resolution setting section to set an output-image resolution, based on an output resolution of the outputting function; and a resolution converting section to convert a resolution of either the image data or the binary-coded image data, stored in the image-data storing section, to the output-image resolution set by the resolution setting section.

Abstract: A dithering system yielding two-dimensional dither functioning is implemented without line memories. For each primary input color, a feedback loop outputs an color input signal plus error that can be preset to different values. The desired result is that vertical artifacts on a display formed from the output signals are relocated to different locations on consecutive display lines. If signal magnitude from the feedback loop output exceeds the magnitude of the video system creating the display, signal magnitude is preset to a value representing error at the start of the display line.

Abstract: A method of one embodiment of the invention is disclosed that determines to output an output pixel for a color component of an image pixel. In response to determining to output the output pixel for the color component of the image pixel, the method outputs this output pixel, and at least substantially precludes output of output pixels for other color components of the image pixel.

Abstract: A method and apparatus for performing ink reduction error diffusion are described. In one embodiment, the method comprises performing vector error diffusion and mapping anchors to printing colors, where performing vector error diffusion includes quantizing each input pixel value to a closest anchor in an anchor set, calculating errors based on differences between the input pixel values and the anchors, and performing error filtering based on calculated errors.

Abstract: Entered image data is stored in a page buffer on a per-page basis, and image data that has been stored in the page buffer is subjected to error diffusion processing on a per-raster basis, thereby creating and outputting binarized data. Sub-scanning direction error due to error diffusion processing is stored in an error buffer at the time of binarization. The error buffer is initialized based upon positions, in the sub-scanning direction, of a raster that underwent error diffusion processing immediately previously and a raster to undergo error diffusion processing, and the number of rasters on a page. As a result, it is possible to avoid a deterioration in image quality at page boundaries and at the beginning of an image simultaneously when data for printing on elongated sheets of paper is processed.

Abstract: When image data is converted into an expression format based on the dot on-off state, such conversion is performed in a unit of a raster group comprising a predetermined number of adjacent rasters. When this is done, the binarization errors occurring in each pixel of the last raster located in the last position of such raster group are diffused into surrounding pixels and stored in a first storage unit. The errors are read out from the first storage unit for dot on-off state determination regarding the first raster of the raster group adjacent to the above-mentioned last raster, and binarization errors occurring in connection with this determination are stored in a second storage unit that permits faster reading and writing of data than the first storage unit.