Abstract: A method for enhancing the print quality of halftone images makes use of error diffusion to perform halftone image processing to a document. After an RGB image is obtained by scanning the document, a high-pass filter is used to detect the edge characteristics and edge directions of the RGB image. Next, during the error diffusion process, a condition quantizer is used to separately process pixels both with and without edge characteristics based on the edge characteristics, gray scale values, and accumulated errors of input pixels. Pixels without edge characteristics can thus have a smoother distribution by means of error diffusion, and the pixels with edge characteristics can have a concentrated distribution, thereby the edge of the text in the document can be sharpened.

Abstract: An image recording apparatus (2000) is disclosed, which includes forming elements (2002) for forming an image, a memory (2006) indicating relative desirability of utilizing the forming elements (2002) for forming the image, and processing unit (2008) for computing image recording signals using input image signals (2012) and the stored data. The use of a particular forming element is thereby biased dependent upon the relative desirability data for the other forming elements and the corresponding input image signals for the other forming elements.

Abstract: A band plotting processing unit analyzes input data to plot in pixel units an image of RGB data corresponding to a character image to be printed, analyzes the input data to generate micropixel RGB data of a low resolution and micropixel shape information (DOT information) of a high resolution. The low resolution image is then converted to a high resolution output image based on the RGB data, the DOT information, and the micropixel RGB data stored in a main memory.

Abstract: An image processing device converts multi-gradation image data to low-gradation image data for outputting an image of a dot pattern that is formed by a high-density first part formed in a band shape by dots connected in a predetermined direction and a low-density second part formed by randomly arranged dots.

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: A method for halftoning an image using an error diffusion process generates an upper threshold level and a lower threshold level and selects a region number parameter. A pixel from the input image is selected and compared to the upper and lower threshold levels. A first pixel value is output when the input pixel value is below the lower threshold level. The first pixel value is output when the input pixel value is below the upper threshold level and above the lower threshold level and a value of the input pixel divided by the region number parameter, modulo 2, equals zero. A second pixel value, the first pixel value being different from the second pixel value, is output when the input pixel value is below the upper threshold level and above the lower threshold level and a value of the input pixel divided by the region number parameter, modulo 2, is greater than zero. The second pixel value is output when the input pixel value is above the upper threshold level.

Abstract: The input pixels in an image to be halftoned using error diffusion are dithered using a first type of passband dither. A second type of passband dither may also be added to a thresholding matrix used in halftoning. This second type of passband dither may be the same as the first type of passband dither. In such case, the second type of passband dither is a scaled multiple of the first type of passband dither. The halftoning process may be implemented in an application specific integrated circuit.

Abstract: A method for processing a digitized continuous tone image for reproducing the image by a printing device, including (a) inputting a tone value of an input pixel of the image; (b) applying a plurality of levelsplit curves to the tone value, thus obtaining a plurality of level values, wherein each specific levelsplit curve of the curves corresponds to a level defined by (i) a combination of a dot density and a dot area; or (ii) an overlap of a plurality of such combinations; (c) inputting the plurality of level values to an error diffuser for obtaining an output pixel value for reproducing the image; wherein a fraction of the output pixels to be filled by an overlap of levels depends on the level values and is independent of the error diffuser.

Abstract: A disclosed inkjet recording apparatus for performing recording by jetting a recording liquid onto a recording medium includes an image processing unit configured to obtain an output halftone level by performing halftone processing on input image data, to select a dot arrangement order according to the obtained output halftone level, and thereby to generate dot data where dots are arranged in a grid-like pattern. The disclosed inkjet recording apparatus is configured to use a pigmented ink as the recording liquid when the recording medium is a commercial printing paper, and to record the dots in a staggered arrangement where positions of the dots in odd/even-numbered columns or odd/even-numbered rows in the dot data are shifted in a sub-scanning direction or in a main-scanning direction.

Abstract: A system and method for performing threshold stamping are disclosed. First and second threshold values corresponding to first and second pixels may be retrieved from a threshold memory. A plurality of upscaled threshold values may optionally be computed based on the first threshold value and the second threshold value. An (upscaled) threshold value may be updated at each of one or more first register blocks. A binary pixel value may be computed based at least in part on the first updated threshold value. The first updated threshold value may be updated at each of one or more second register blocks. A downscaled threshold value may optionally be computed based on a plurality of second updated threshold values. The downscaled threshold value or second updated threshold value may be damped in a damping circuit, and the damped threshold value may be stored in the threshold memory.

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 spaces out the output of output pixels for other color components of the image pixel.

Abstract: An error adding step adds together input multi-tone image data and peripheral error information. An adding/subtracting step adds to or subtracts from multi-tone image data calculated by the error adding step, a random number in a matrix prepared for each set of pixels of the input multi-tone image data. A quantizing step quantizes multi-tone image data calculated by the adding/subtracting step into image data, the number of bits of which image data being smaller than the number of bits of the multi-tone image data calculated by the adding/subtracting step. An error calculating step calculates an error based on the multi-tone image data calculated by the error adding step and the image data quantized by the quantizing step. An error storing step stores the error calculated by the error calculating step for each peripheral pixel.

Abstract: An image processor includes: a gradation value acquisition unit that acquires a gradation value of a pixel of interest which is a pixel sequentially selected as a target of a binarization process from input image data represented by pixels of M gradations, wherein M?3; and a pattern determination unit that determines a filling pattern of a group of pixels of output image data corresponding to the pixel of interest according to a corrected gradation value acquired by adding, to the gradation value of the pixel of interest, an error value diffused from a pixel at a periphery of the pixel of interest, wherein the filling pattern includes at least a first pattern in which a predetermined plurality of pixels are filled and which forms a core of a dot and a third pattern in which substantially no pixel is filled and the pattern determination unit determines the filling pattern to be one of the first pattern and the third pattern according to a size relationship between the corrected gradation value and a predetermi

Abstract: N rasters of multi-valued data indicating a halftone image is input to a buffer and a pixel of interest to be quantized is quantized for the input multi-valued data. Furthermore, error of a quantized pixel is distributed to peripheral pre-quantization pixels including pre-quantization pixels in a raster of pixels quantized before the quantized pixel, and error distributed with respect to the pixel of interest is added to the multi-valued data for which quantization is yet to be processed. And the quantizing and distributing and adding of error are repeated while moving the pixel of interest in a column direction, and, when processing of N pixels has been completed in regard to the column direction, equivalent processing is repeated while moving the pixel of interest in a raster direction, thereby quantizing the multi-valued data of the N rasters.

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 printing control method of generating print data to be supplied to a print unit capable of forming dots on a print medium by ejecting ink droplets of at least one type of colored ink containing a color material and a quality-enhancing ink for enhancing quality of a printed material. The printing control method comprises a tone-decreasing step which includes the step of generating transparent dot data by a process configured such that size of first processing-targeted pixels is larger than size of second processing-targeted pixels, the first processing-targeted pixels being targeted for processing in the transparent dot data generating process, the second processing-targeted pixels being targeted for processing in the colored dot data generating process.

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: Error diffusion is performed using a Floyd-Steinberg-like approach. A integer-representation of a running error is compressed by storing only its most significant bits and returning any remainder to the error diffusion processor. The running error is shifted to the right until only the desired number of significant bits remain, and this compressed error is stored. Any portion of the original running error that is lost due to the shifting is treated as a remainder and is returned to the error diffusion processor for use in calculating an adjusted current pixel value. The amount of the shift is retained in compressed form to keep track of the number of shifts needed to form a truncated running error from the compressed running error.

Abstract: In order to reduce time required to perform error diffusion processing on one line of image data, one line of multi-tone image data 100 is divided into two or more segments of image data 102 and 103 with an overlapped region 101 provided across the boundary. The two or more segments of image data 102 and 103 are subjected to error diffusion to create binary image data 104 and 105 corresponding to the divided image data 102 and 103, respectively. Then the binary image data 104 and 105 are merged to form binary data 106 corresponding to the original image data of one line. Upon merging the binary image data, binary data b2 obtained from the divided image data 102 located upstream of the line before divided in the direction in which the error diffusion processing progresses is used as binary data corresponding to the overlapped region.

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: A method of revising an edge region and an image forming device using the same. The method of revising an edge region includes detecting edge regions from a half-toned image, and adjusting colors with respect to an edge region where a plurality of colors overlap each other among the detected edge regions in accordance with an existence/nonexistence of a black color in the edge region, while adjusting an edge region of a single color with respect to the edge region where the single color exists.

Abstract: An image forming apparatus, for forming an image with plural types of dots having different densities per unit area in a same hue, including: a section to compare between a pixel value of a target pixel and a value of a prescribed threshold value matrix, and to determine, based on the comparison, whether to form a first type of dot at a position corresponding to the target pixel; a section for calculating a corrected threshold value matrix from the prescribed threshold value matrix; a section for calculating a second determining condition by reflecting the corrected threshold value matrix; and a section for determining whether to form the second type of dot, based on a target pixel value added an error with an error diffusion process and the second determining condition, at the position where the first type of dot has been determined not to be formed.

Abstract: An apparatus and method are provided to accelerate error diffusion for color halftoning for embedded applications. High performance is achieved by utilizing functional parallelism within the halftoning error diffusion process, including exploiting data parallelism in different color planes, reducing the number of memory accesses to the error buffer, accelerating the computation by using a parallel instruction set, and improving the throughput of the system by implementing pipelined architecture. A halftoning coprocessor architecture can implement the foregoing. The architecture can be optimized for high performance, low complexity and small footprint. The coprocessor can be incorporated into embedded systems to accelerate the performance of error diffusion halftoning therein.

Abstract: When the image data having a predetermined gradation value for each pixel is input, and the image data is searched from the initial pixel and the total of the gradation values of the pixels, including the searched pixels, becomes a predetermined threshold value or more, a dot is generated at the center of the gravity position as a quantized pixel group. In the searching, an unprocessed pixel closest to the center of gravity position, including this pixel, is selected. If there are a plurality of unprocessed pixels, selection is performed at random. For the pixel selection, a pixel closest to the center position computed from the positional coordinates may be selected, rather than the center of gravity. Also a dot may be generated at the center position of the quantized pixel group.

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: An image processing apparatus includes an inputting unit to receive image data having pixel data, an image processing unit to align and output the pixel data, and a control unit to prevent the pixel data from being transmitted to the image processing unit when the pixel data have null data.

Abstract: An image processing device includes a pre-processing unit, an adder, a quantization unit, a post-processing unit and a surrounding error calculating unit. The pre-processing unit calculates an average pixel value of an aggregated pixel formed of a plurality of adjacent pixels for input image data. The adder calculates a correction average pixel value by adding a correction error value to an average pixel value of a target aggregated pixel to be a processing object. The quantization unit carries out a quantization processing of the correction average pixel value at a quantization level of a prescribed number. The post-processing unit divides the aggregated pixel into a plurality of pixels and allocates a pixel value corresponding to the quantization level to each of the divided pixels. The surrounding error calculating unit calculates a correction error value for processing a surrounding target aggregated pixel in accordance with a quantization error generated in the quantization processing.

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: 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 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: 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 image processing system including a lookup table having multi-bit printer output levels and an imaging input level. The imaging input level may be associated with a range of input pixel densities. The system further includes a processor configured to compare the imaging input level with one or more preconfigured threshold output values associated with the printer output levels. The imaging input level may be preferentially weighted to select a printer output level having an increased bit depth.

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 image processing apparatus, a printing apparatus and an image processing method are provided which can perform quantization processing on image data at high speed based on an error diffusion method while at the same time avoiding degradations in a quality of printed images. When an error value represented by error data is a particular value, the error data is converted into compressed error data with a data volume less than that of the original error data.

Abstract: A method of printing dots in an area on a page using a plurality of printing passes of a printhead over the area, includes processing continuous tone data through a halftoning mechanism to generate halftone image data; and processing the halftone image data through a plurality of error diffused shingling masks, each error diffused shingling mask of the plurality of error diffused masks being used once on a particular pass of the plurality of printing passes in printing the area.

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: An image processing apparatus includes: a recording rate determining section for determining a recording rate of each of a plurality of dot types having different densities per unit area from each other according to an input value including a multi-gradation image data, the input value being quantized for forming a dot of the plurality of dot types; a dot formation judging section for judging whether the dot is to be formed on each pixel based on a sum total of each recording rate of the plurality of dot types; and a dot selecting section for selecting a dot type among the plurality of dot types having different densities per unit area from each other to a pixel on which the dot formation judging section judges that the dot is to be formed, wherein an image is formed according to an arrangement distribution of the dot.

Abstract: Disclosed are methods of halftoning images having multiple color planes using error diffusion techniques, and incorporating both error information from the previously-processed color planes of a pixel, and error information from a previously process pixel of yet-to-be processed color planes.

Abstract: A method of adjusting a TRC of an image is provided. The method involves receiving an image at an input resolution, resampling the image to a processing resolution if the imput resolution and the processing resolution are not same, processing the image using rank-ordered error diffusion, and resampling the processed image to a desired output resolution for the image if the processing resolution and the output resolution are not same.

Abstract: In image processing carried out by means of repeated execution of process set which includes N unit processes (where N is an integer equal to 3 or greater), prior to execution of the process groups, the N unit processes are assigned to a number M (where M is an integer equal to 2 or greater, but less than N) of processing modules for executing the unit processes. First, on the basis of execution results of unit processes included in the process group executed immediately prior, there is estimated an estimated load of unit processes of each class in the next process group. Then, on the basis of the estimated load, the N unit processes are assigned to the processing modules. During this process, a selected unit process which is one of the unit processes not yet assigned to a processing module, is assigned to one of the processing modules.

Abstract: An image processing method, apparatus, and program as well as a printer, a print instructing terminal, and an image processing system, capable of reducing or preventing deterioration of the image quality and achieving binarization at high speeds is provided. An image processing method, by which a multi-grayscale image is divided into two regions. These regions are synthesized after error diffusion processing is applied to each region. Before the original image is divided into two regions, errors of respective pixels on a dividing line are diffused to these two regions. It is thus possible to obtain substantially the same processing result as in a case where the error diffusion processing is applied continuously across the entire original image. Hence, it is thus possible to reduce or eliminate stripes or the like in the joined portion that deteriorate the image quality when the divided regions are synthesized after the error diffusion processing, which enables a high-quality image to be obtained.

Abstract: A computer serving as an image processing device produces pixel groups by assembling a plurality of adjacent pixels among the plurality of pixels forming the image data, and determines the pixel group tone value for each pixel group. Number data corresponding to the pixel tone values of the pixel groups is then obtained based on a predetermined correspondence. At that time, tone errors occurring during the conversion of the pixel group tone value to number data are diffused to the surrounding pixel groups so as to be reflected in the calculation of the pixel group tone values. The computer outputs the resulting number data to a printer. The printer, which serves as an image generating device, determines the position of the pixels by which the dots are formed in the pixel groups based on the number data that has been obtained, and drives a printing head to form dots in those positions.

Abstract: An ink saving and tone correction printing technique using error diffusion (EDF) includes receiving a first pixel value vi,j and comparing the first pixel value vi,j with a threshold value to produce a second pixel value bi,j and a reference value pi,j. When the first pixel value vi,j is less than a threshold value, not outputting the second pixel value bi,j and the reference value pi,j is the area of actual non-blank region within a pixel region. When the first pixel value vi,j is greater than the threshold value, outputting the second pixel value bi,j for printing on the pixel region, and the reference value pi,j is the area of actually increased non-blank region within the pixel region and the adjacent pixel regions in which a processing prior to printing has been conducted to decide whether or not to print.

Abstract: A method is provided of reproducing continuous tone pixel colors of a color image having many pixels based on Kueppers' device states, wherein the Kueppers' device states of a printing device are the printed pixel colors that are allowed based on Kueppers' color separation and halftoning. The method includes selecting a Kueppers' device state in the proximity of a continuous tone pixel color to be reproduced from the printing device's set of Kueppers' device states, and printing the Kueppers' device state. An error is diffused between the continuous pixel color and the selected Kueppers' device state to one or more pixels in the neighborhood.

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

Abstract: A macro-pixel used in an image rendering process for forming an image using a matrix of macro-pixels. The macro-pixel comprises a plurality of rectilinear parallel rows. All rows extend across the matrix in the same direction and each one of the rows is capable of at least partially adopting at least one of a color state and an off state. The on state includes the presence of color while the off state includes the absence of color. The on state comprises non-key and/or key colors. The non-key colors can be cyan, magenta, yellow, and/or any other color while the key color is normally black. The macro-pixel also includes columns formed by micro-pixels which may be turned on in a predetermined order. The predetermined order permits maximum distance between rows used for key colors and rows used for non-key colors.

Abstract: An image processing circuit includes: a plurality of counters that extract image blocks each of which includes a predetermined number of pixels from input image data, count a number of pixels having a predetermined value for each of the image blocks, calculate a pixel value for each of the extracted image blocks, and output a plurality of bit streams each of which represents the counted number for a respective image block, the number of the plurality of counters being larger than a bit length defined for a single writing process with the memory divided by the bit length of a value calculated for an image block; a converter that converts the bit streams output from the plurality of counters, by adjusting a bit length of the bit streams for writing in the memory, and outputs the converted bit streams; and a synthesizer that synthesizes the plurality of bit streams output from the converter to generate a bit stream having the bit length defined for a single writing process with the memory, and outputs the genera