Abstract: An image processing apparatus includes an integer-part converting unit configured to convert multi-level image data into integer image data by referring to a first conversion table, a threshold setting unit configured to generate matrix data for performing area coverage modulation by referring to the multi-level image data, a decimal-part converting unit configured to convert the multi-level image data into decimal image data by referring to a second conversion table, a level reducing unit configured to reduce levels of the decimal image data by using a threshold generated in the threshold setting unit, an adding unit configured to add the integer image data to the level-reduced decimal image data and outputting a result of addition as gamma conversion image data, and an image processing unit configured to perform image processing on the gamma conversion image data.

Abstract: Dot patterns formed by two different half-tone processes of the plurality of tone processes for each color of CMYK and formed with/without the presence and absence of transparent toner overlap are created and test patches obtained by collecting the dot patterns are printed. The printed test patches are read to generate image data, and tone correction arithmetic is performed on the basis of the image data. Concentration in the case of the presence of transparent toner in a different half-tone process is predicted based on the dot patterns with the transparent toner overlap in the test patches and concentration in the case of the absence of transparent toner in a different half-tone process is predicted based on the dot patterns without the transparent toner overlap in the test patches. The tone correction arithmetic is performed based on the predicted values.

Abstract: A printing apparatus is provided with a halftone unit performing a halftone process in which a possibility of dot formation is determined for each pixel based on a dot occurrence rate of the pixel constituting image data, and a printing unit forming dots on a recording medium based on the possibility of dot formation. The halftone unit predicts the occurrence of dot overlap in which a plurality of dots overlaps on the printing medium and performs the halftone process based on an evaluation index according to the dot overlap.

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

Abstract: An image processing apparatus including: a determining processing section which binarizes a pixel value of a target pixel using a threshold; a calculation section which calculates feedback values by multiplying binarized pixel values of adjacent processed pixels by a feedback coefficient; a addition section which adds the feedback values to the pixel value of the target pixel before binarization; a diffusion section which diffuses a difference between the binarized pixel value and the unadded pixel value as an error to adjacent unprocessed pixels; and a subtraction section which subtracts the error from the unadded pixel value of the target pixel, wherein when all pixel values of processed pixels are 0 and an output value of the target pixel is a maximum value, it is determined that the target pixel is an isolated point and an output value of an adjacent pixel is set to a forced output value excluding 0.

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

Abstract: An image glossiness controller has a main component color specifying unit that identifies a prescribed component color and output identification information thereof. A change in amplitude of a convexoconcavity of a toner layer of the prescribed component color is greatest among those of the other component colors when each of the component color toner is formed and fixed alone. Three or more halftone dot signal generators convert clear toner image information into three or more binary clear toner image signals corresponding to three or more component colors per component color pixel using multiple halftone dot characteristics, respectively. Each of the multiple halftone dot characteristics generating three or more binary clear toner image signals has a reversed phase from that generating three or more binary component color image signals.

Abstract: An image processing apparatus is configured to process multivalued image data corresponding to a unit area of a recording medium so as to form an image on the unit area with a plurality of relative movements between a recording head and the recording medium. The apparatus has a selecting unit for selecting either a first processing mode to segment the multivalued image data into a plurality of multivalued image data corresponding to the plurality of relative movements, and then quantize each of the plurality of multivalued image data, or a second processing mode to quantize the multivalued image data into quantized image data, and then segment the quantized image data into a plurality of quantized image data corresponding to the plurality of relative movements. The selecting unit may select either the first processing mode or the second processing mode based on the number of relative movements to the unit area.

Abstract: When recording is performed in a pixel region by M (M is an integer equal to or larger than 2) passes with N (N is an integer equal to or larger than 2) recording element groups, density variation due to a deviation between recording positions of dots that are recorded by different passes is suppressed while a load of data processing is decreased. First, multivalued image data (24-1 to 24-2) corresponding to the M passes is generated from input image data, and the multivalued image data corresponding to the M passes is quantized to generate quantized data (26-1 to 26-2) corresponding to the M passes. Then, the quantized data corresponding to the M passes is divided into quantized data being complements of each other and corresponding to the N recording element groups. Accordingly, the quantized data (28-1 to 28-4) corresponding to the M passes for the N recording element groups is obtained.

Abstract: An image reading apparatus that optically reads a document includes: multiple line sensors provided approximately parallel to each other and each having light-receiving elements arranged in line form, each line sensor capturing respective line-shaped regions spanning in the main scanning direction of the document in respective color components; a movement unit that causes the positional relationship between the document and the multiple line sensors to move relative to the sub scanning direction that is orthogonal to the main scanning direction; a color skew adjustment unit that adjusts positional skew in the sub scanning direction in scan data of each of the color components captured by the multiple line sensors in synchronization with the movement caused by the movement unit, in accordance with an offset amount based on the distance between each of the multiple line sensors.

Abstract: The image processing apparatus executes quantization processing of second multi-valued image data that corresponds to a second relative movement of a plurality of relative movements based on first multi-valued image data that corresponds to a first relative movement of the plurality of relative movements, and executes quantization processing of the first multi-valued image data based on the second multi-valued image data. This makes it possible to output a high-quality image having excellent robustness and reduced graininess by controlling the overlap rate of dots that are printed by the first relative movement and the dots that are printed by the second relative movement.

Abstract: An image forming apparatus having a recording head with a plurality of printing elements comprising: a first quantization unit that performs a first quantization process on input image data to calculate N-level data by using a screen parameter corresponding to a screen condition of a target device; a conversion unit that converts the N-level data to M-level data (M>N); a configuring unit that configures printing density for each of the printing elements for each scan, using the M-level data; a second quantization unit that performs a second quantization process on the printing density for the scan of interest, using constraining information for the scan of interest; and a generating unit that generates the constraining information for the scan of interest, from the printing density configured for the preceding scan and the result of the second quantization process for the preceding scan.

Abstract: A plurality of color data respectively undergo quantization processing, and a logical multiplication of the plurality of quantized color data is calculated. A product of the plurality of color data is calculated. A first low frequency component is extracted from the logical multiplication, and a second low frequency component is extracted from the product. The first low frequency component is subtracted from each of the plurality of color data, and the second low frequency component is added to the subtraction results to generate a plurality of corrected color data. The plurality of corrected color data respectively undergo the quantization processing.

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: Systems and methods are described that facilitate reducing a number of patches used in characterizing a color halftone printer via a binary color printer model. A binary printer model involves printing of a fundamental set of color binary patterns that encompass all possible halftone outputs. A k-center clustering technique is employed to automatically find and eliminate redundancies in the initial set of binary color patterns. Once the number of patches is reduced to an acceptable number, a multiplicative reflectance model is applied that better approximates the physical process and therefore improves accuracy.

Abstract: A region for quantization having a value lower than the value B is assumed as having little influence by Bk data on the pixels in this region. Thus, in order to prioritize the optimization of the granularity at the start of the input of GY data, the LUT having a combination of GY and gy as an input as an input is used to perform separation quantization. On the other hand, since a region having a value equal to or higher than the value B requires the use of Bk data, the LUT having only a combination of Bk and GY as an input as an input is used to perform quantization. As a result, the number of types of pieces of ink data referencing the table can be 2, thus suppressing an increase in the table size.

Abstract: A printing method, and an image forming apparatus and image forming system to perform the method, the method including performing a multi-bit halftoning of a pixel of image data if the pixel is to be printed with a dark developer, performing a single-bit halftoning of the pixel if the pixel is to be printed with a light developer, and printing the halftoned image data.

Abstract: A scan line profile characteristic representing the distortion of a scan line is detected. Dot image data undergoes the screen process using a dither matrix. At this time, the quantization process is done by shifting a dither matrix element in the sub-scanning direction opposite to the direction of the scan line changing process at a scan line changing point in the scan line changing process in accordance with the profile characteristic. The image data after the screen process undergoes the scan line changing process, and the interpolation process smooths the scan line changing point.

Abstract: Halftoning apparatus and method that may generate and employ average values and shifts are described herein. The apparatus may include an unpacker to determine shifts and average values for a plurality of input pixel values, each pair of average value and shift being associated with a corresponding pair of the input pixel values. The apparatus may further include a halftone core coupled to the unpacker to receive the shifts and the average values from the unpacker and to generate pairs of output pixel values based at least in part on the received shifts and average values, wherein the output pixel values are for generating pixels of an image.

Abstract: The present invention provides an image-processing apparatus, including: a corrected value calculating unit configured to calculate corrected values by adding error values diffused from a pixel neighboring a pixel currently being processed respectively to a plurality of input values corresponding to the pixel currently being processed; a total value calculating unit configured to calculate a total value of all corrected values; a quantizing unit configured to quantize the total value; a distributing unit configured to calculate a plurality of output values corresponding to the plurality of input values by distributing the quantized value according to a ratio between each of the corrected values and the total value; and an adding unit configured to calculate respective difference values between the plurality of output values and the plurality of corrected values, and to add the calculated difference values to corrected values.

Abstract: An image processing apparatus includes a storage unit storing an image and a processing unit performing image processing in each segment of the stored image to obtain a value of each pixel in a predetermined order using calculation results for peripheral pixels processed. At least one segment is a quadrangular area. Two sides of the quadrangular area extend from a first vertex of two opposite vertices of the area toward two of subsequent pixels after a first pixel at the first vertex so that the area includes the subsequent pixels whose values are obtained using a calculation result for the first pixel. The other two sides extend from a second vertex of the two vertices toward two of previous pixels before a second pixel at the second vertex so that the area includes the previous pixels for which a value of the second pixel is calculated using calculation results.

Abstract: An image processing apparatus controls a formation of dots in a recording element configured to perform scanning on a sheet-like recording medium to form dots of different colors on a surface of the recording medium. The image processing apparatus makes a constraint according to cyan and magenta constraint information applied to a same scanning operation stronger than a constraint according to cyan and magenta constraint information applied to mutually adjacent scanning operations.

Abstract: An image forming apparatus comprising an exposure device for exposing an image bearing member to light in accordance with monochromatic image data provided by color separation of inputted multi-color image data to form an electrostatic latent image; a control device for calculating an exposure amount of each pixel of the monochromatic image data to expose the image bearing member with the calculated exposure amount; wherein the control device includes a monochromatic correcting device for calculating a correction amount in accordance with a pixel value of a pixel around a target pixel of the monochromatic image data to correct an exposure amount of the target pixel on the basis of the calculated amount; wherein the control device includes a multi-color correcting device for providing a coefficient for correction of the exposure amount on the basis of the multi-color image data; wherein the monochromatic correcting device controls the exposure amount using the coefficient and the correction amount provided by

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: Systems and methods for generating a dynamic re-configuration with a DFE imager and caching modules to optimize RIP performance by analyzing pages within the job that collect page with job heuristics and statistics. Enabling the functionality to assess the information, thereby re-configuring a digital printer's imager and caching module dynamically during the job RIP to achieve improved overall RIP performance. Accordingly, a system collects and assesses job statistics across multiple jobs to enable optimum performance over time.

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: A printing apparatus is adapted to perform printing of image data corresponding to a plurality of pixels representing a predetermined image. The printing apparatus includes a halftone processing section including a comparison section and an error diffusion section. The comparison section is configured to compare, for at least one of the pixels, a related grayscale value relating to a data grayscale value of the input image data with a corresponding one of a plurality of thresholds included in a dither mask. The error diffusion section is configured to generate dot data for indicating the presence or absence of formation of a dot in each of the pixels according to an error diffusion method, on the basis of the data grayscale values of the input image data, and to control the easiness of the dot formation according to the error diffusion method, on the basis of a comparison result of the comparison section.

Abstract: Disclosed is a method for scanning and processing an image using the error diffusion screening technology, comprising: (1) scanning each pixel Mi of an nth line in an original image one by one and then storing a scanning result of the pixel Mi to an ith storage location; and (2) processing the stored result of the pixel Mi by using error diffusion and scanning pixels of an n+1th line in the original image until all pixels of the nth line have been processed and all pixels in the n+1th line have been scanned and stored, wherein once processing for the pixel Mi is completed, a scanning result of a pixel of the n+1th line is stored to the ith storage location previously occupied by the pixel Mi. Based on the method, the capacity for storing is only required to be able to store the data of one line in an image in the scanning direction, which saves the storage for bidirectional scanning. The method can optimize the hardware used to implement error diffusion and improve the operating efficiency.

Abstract: An image processing apparatus that is capable of determining a document size with high accuracy, even when a device for detecting the document size is not placed therein and an input operation of the document size by a user is eliminated is provided. A page background determining section extracts candidates for page backgrounds from input document image data and determines the number of page background types. A white pixel counting section counts the number of white pixels from input document image data. A document size determining section determines the document size of the input document image data, based on the number of page background types determined by the page background determining section, a page background density value which is the lowest density value in one or a plurality of page background areas determined to be page backgrounds, and the number of white pixels extracted by the white pixel counting section.

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: Disclosed are FIFO type methods, systems and apparatus for electronically registering image data relative to a raster or other marking device. According to an exemplary method, a FIFO type data queuing configuration is provided, where the length of data memory segments associated with the FIFO are selected to correspond to the number of raster lines from the most upstream point of the physical raster to the point where the given pixel column intersects the physical raster.

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: The value of a diffusing error for an interest pixel is added to image data of the interest pixel, and is calculated from error data occurred in quantization of pixels adjacent to the interest pixel. The image data, to which the value of the diffusing error is added, is quantized using a quantization threshold. Error data of the interest pixel is calculated from the result of the quantization and the image data to which the value of the diffusing error is added. Pixels which are adjacent to the interest pixel and have quantization results corresponding to the image data of the interest pixel are detected, and information between pixels is calculated based on differences between the image data and quantization results of adjacent pixels which fall within ranges corresponding to the detected adjacent pixels. The quantization threshold for the interest pixel is set based on the information between pixels.

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

Abstract: A printing apparatus performs printing on a print medium. The printing apparatus includes: a dot data generator that performs a halftone process on image data, wherein the print image is formed by mutually combining print pixels belonging to each of a plurality of pixel position groups for which a physical difference is assumed at a formation of dots by the print image generator, in a common print area, and the halftone process is configured to determine the status of dot formation on each of the print pixels on an assumption of the physical difference.

Abstract: In a halftone image after halftone processing, significant dot values within a reference window that encompasses a pixel of interest are accumulated, and by referring to a conversion table based on the accumulated values, a multilevel pixel value that corresponds to that pixel of interest is restored. At this time, the size of the reference window is determined such that a product of a bit depth in the halftone processing and the number of pixels within the reference window becomes a minimum value that exceeds the number of tones in a multilevel image after restoration.

Abstract: Since a less-than-one-pixel-basis correction and a one-pixel-basis correction are constantly performed on an image after halftoning, unevenness in density disadvantageously occur depending on a halftoning method. According to the halftoning method, whether the less-than-one-pixel-basis correction is performed on a continuous tone image or the one-pixel-basis correction is performed on a halftone image is switched. The one-pixel-basis correction is constantly performed on the halftone image.

Abstract: A large-capacity multiplexing system assuring image quality and robustness is provided. An image-processing apparatus multiplexing additional information on image information includes a first multiplexing unit that is configured to perform pseudo-halftone processing so that the image information is changed into a first quantization level of multi-level gradation and that is configured to multiplex first information of the additional information at the pseudo-halftone-processing time, and a second multiplexing unit that is configured to perform the pseudo-halftone processing so that the first quantization level subjected to the pseudo-halftone processing by the first multiplexing unit is changed into a second quantization level of gradation lower than the multi-level gradation and that is configured to multiplex second information of the additional information at the pseudo-halftone-processing time.

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: An image processing apparatus according to this invention performs the first halftone processing for input image data having the first number of gradations, generating halftone image data having the second number of gradations smaller than the first number of gradations. The image processing apparatus evaluates a pixel value difference between input image data and halftone image data, and calculates quantization error data representing a quantization error generated in the halftone image data owing to the first halftone processing. Then, the image processing apparatus performs the second halftone processing for the calculated quantization error data, generating correction data having the second number of gradations for correcting the quantization error generated by the first halftone processing. The image processing apparatus corrects the halftone image data using the correction 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 for controlling an image processing apparatus includes obtaining image data from a detachable memory unit, estimating whether the obtained image data is image data read by a scanner, and in a case where it is estimated that the obtained image data is image data read by the scanner, performing control not to execute predetermined screen processing on the image data.

Abstract: A mechanism for providing edge enhancement or attenuation in a vector error diffusion process includes warping a marking decision color space as a function of at least one pixel value of a target pixel. The warping changes the membership of sets of error modified pixel values associated particular sets of marking. The warping is controlled by a function of pixel values of a target pixel from an input image. Therefore, the warping is constant for uniform portions of the image. Since pixel values change at edges or where colors change, a mechanism is provided for the presence of edges to influence the vector error diffusion process. Selection of the function by which the marking decision color space is warped provides a means for controlling the aggressiveness of the edge enhancement or attenuation. Equivalent processing includes warping or adjusting error modified pixel values according to corresponding functions.

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: This invention is directed to efficiently compressing data used in an image process for an unprocessed line adjacent to a process line in an image data process for each line, and reducing the memory band. To accomplish this, processed image data is compressed, and it is determined whether the process direction of image data of the next line is the first direction or the second direction opposite to the first direction. The data organization of the compressed image data is changed in accordance with the determination result. A memory stores the compressed image data whose data organization has been changed. The compressed image data stored in the memory is read out and decompressed. An image process is performed using the decompressed image data and image data of a line adjacent to the line of the processed image data.

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.