Abstract: A method and apparatus for performing color plane adjustment are provided. In one embodiment, an apparatus comprises a set of inputs for receiving a first input value and a second input value in a color space. The apparatus also comprises a color plane adjustment component operative to adjust the first input value and the second input value by amounts that depend on a distance of the first input value and second input value, respectively, from a value of neutral gray in the color space. The apparatus further comprises a set of outputs for outputting the adjusted first and second values. A related method and computer program are disclosed. Other embodiments are disclosed, and each of the embodiments can be used alone or together in combination.

Abstract: An image processing method is used to converting a color within a first color reproduction range that is a device-independent color space into a color within a second color reproduction range that is a color reproduction range of an output device. The image processing method includes defining, within the first color reproduction range, a third color reproduction range of a color that is estimated to be input; defining, within the second color reproduction range, a fourth color reproduction range that is smaller than the second color reproduction range; and, in performing the color conversion, compressing a color within the third color reproduction range into a color within the fourth color reproduction range and compressing a color within the first color reproduction range and outside the third color reproduction range into a color within the second color reproduction range and outside the fourth color reproduction range.

Abstract: An object of an input print job is discriminated, and color conversion processing is applied to the object of the print job based on the discrimination result and information which is set in correspondence with the print job and is used to designate color conversion processing. When the object is a transparent object, the color conversion processing is executed on a rendering color space, and when the object is a gradation object, the color conversion processing is executed on a device color space.

Abstract: Systems and methods, including computer software products, for processing gray colors in a conversion between color spaces involve identifying a non-pure gray color value in a color space that represents a substantially gray color. The methods further include converting the non-pure gray color value to a corresponding pure gray color value in the color space. The methods also include determining a first difference vector between the non-pure gray color value and the corresponding pure gray color value. The methods further include determining a distance between the corresponding pure gray color value and a selected color value. The corresponding pure gray color value represents a nearest pure gray color value to the selected color value. The methods also includes determining a correction factor based on the first difference vector and the distance and applying the correction factor to the selected color value to produce a corrected color value.

Abstract: Embodiments of a method performed by an image capture device are provided. The method includes performing a calibration operation on a photosensor array of the image capture device using a background surface with a substantially uniform grey color and performing a scan operation to capture a scanned image from a medium using the background surface.

Abstract: An image forming device that carries out color reproduction using plural of color materials having: a setting unit setting a color material curbing mode that curbs an amount of color material; and a color information inputting unit that inputs input color information. The image forming device further has a converting unit that, when the color material curbing mode is set by the setting unit, converts the input color information inputted by the color information inputting unit into output color information in a color material curbing region, on the basis of correspondence relationships that are set in advance such that a region that is color-reproducible by the image forming device is kept within the color material curbing region that is narrowed such that an amount of the color material is curbed.

Abstract: An image processing method includes: inputting color image data obtained by capturing an image at a given imaging sensitivity level; and converting the color image data to a specific uniform color space determined in correspondence to the imaging sensitivity level.

Abstract: According to one embodiment, a gradation control apparatus comprises a coring module configured to change the coring amount of a video signal according to the degree of movement of the video signal, a smoothing module configured to perform a gradation smoothing process on the video signal, and a parameter controller configured to obtain a frame difference histogram as the degree of movement of the video signal and change an effect parameter for the gradation smoothing process according to the result of weighting the histogram.

Abstract: A high-quality monochrome photographic image is formed using a high-resolution color ink-jet recording apparatus. When a monochrome mode is selected, density signals are produced such that they include at least one density signal corresponding to a chromatic color material and a density signal corresponding to an achromatic color material and having a value greater than the value of the at least one density signal corresponding to the chromatic color material. A slight recorded color deviation that can occur when the achromatic color material is recorded on a recording medium is compensated for by adding a small amount of chromatic color material having a hue which cancels out the recorded color deviation. Thus, a high-quality gray scale image is obtained without having recorded color deviation or color transition.

Abstract: Automatically selected adjusters are described, including selecting an area of an image, determining a characteristic of the area, and selecting an adjuster of a set of adjusters based on the characteristic of the area.

Abstract: Systems and methods are provided for dynamically converting first color data to second color data using a look-up table, wherein the first color data is a subset of a first color space, and the second color data is a subset of a second color space. In some embodiments, at least one first color value is input in the first color data. At least one look-up table entry may be calculated for the at least one first color value in the first color data, if the look-up table entry has not been previously calculated. The at least one calculated look-up table entry may be stored. At least one value in the second color data, which corresponds to the at least one first color value, can be computed based on the at least one first color value and the stored value of the at least one look-up table entry.

Abstract: An input gradation converting circuit has a gradation conversion table in which M-bit intermediate gradation data are correlated with each of N-bit input gradation data, and is operable to convert each of the input gradation data into the M-bit intermediate gradation data by using the gradation conversion table and output the converted M-bit intermediate gradation data. A diffusion gradation converting circuit is operable to convert each of the intermediate gradation data outputted from the input gradation converting circuit into N-bit output gradation data and output the converted N-bit output gradation data. The diffusion gradation converting circuit acquires a uniform random number Rnd in the range of ?SFT/2 to SFT/2 and outputs [X+Rnd+0.5] as the output gradation data for each of the intermediate gradation data in which X obtained by dividing a value of the intermediate gradation data by 2M·N and a specified value SFT satisfy a conditional expression “SFT/2?[X]?2N?1?SFT/2” (where [ ] is a Gauss symbol).

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: Systems and methods for limiting total colorant in a color rendering system are disclosed. Implementation of the present invention provides for transformation of a specified colorant in which the sum of the colorant components exceeds a total area coverage (TAC) limit to create a second or resultant colorant in which the sum of the colorant components is within the limit. Using a bijective transformation, colorant sampling and other manipulations can be performed using a nominal hypercube space and the results can be compressed from the nominal space back to the actual colorant-limited space, simplifying manipulation of the colorant-limited polytope space. The unlimited colorant hypercube may be divided into simplexes. For each simplex, intersection points may be found between the TAC limit and the edges of the simplex. A barycentric interpolation technique may then be used to map the unlimited simplex onto a corresponding simplex within the colorant-limited polytope.

Abstract: Methods and systems in an image processing device for controlling colors that are located external to a gamut are disclosed. A plurality of color values can be automatically provided as input to said image processing device, wherein said image processing device is under a control of a particular dimensional order, typically a three-dimensional order, but alternatively can be a two-dimensional order. Next, an operation can be performed dynamically determining which color value among the plurality of color values has attained a gamut limit. Thereafter, the particular dimensional order can be automatically reduced, thereby providing improved control for colors that are located external to said gamut. The plurality of color values analyzed is generally associated with three colors—cyan, magenta, and yellow.

Abstract: An image data conversion apparatus for embedding a second image into image data corresponding to a first image, comprising an embedded image acquisition unit that acquires a second image for embedding in the first image, an embedment area acquisition unit that receives a location of an embedment area where the second image may be embedded in the first image, an ink set memory unit that stores a first and second set of inks and associated quantities, wherein the second set of inks and may be substituted for the first set of inks, and an ink amount data conversion unit that converts the image data into converted ink quantity data that corresponds to the image data such that the second image embedded in the first image can be observed by making a differentiation between portions of the first image where the first and second set of ink are used.

Abstract: What is disclosed is a novel system and method for reducing process color banding due to printhead non-uniformities in a direct marking device. In one example, a first measurement of a printhead spatial non-uniformity is obtained along a first line in a color space which produces a spatial uniformity when a target primary color is printed alone. A first spatial tone reproduction curve is generated. A second measurement of the printhead spatial non-uniformity is obtained along a second line in color space in a coverage area of a process color which maximally changes a halftone structure of the target primary color. A second spatial TRC is generated. The first and second spatial TRCs are combined using a weighted average which balances the primary and process colors. A modified spatial TRC is generated. The printhead is adjusted at a location of the target primary color according to the modified spatial TRC.

Abstract: A profile generator determines differences between the standard spectral reflectances of a color chart printed under standard density conditions and the spectral reflectances of a color chart printed while the density of one of the colors C, M, Y, K is changed, and the densities of the other colors are secured to standard densities. When density variations are established, the profile generator generates a print predicting profile using spectral reflectances produced by adding the standard spectral reflectances and the difference with respect to the color whose density has changed. The colors of a print produced when the density of a desired color is changed are predicted with high accuracy using the print predicting profile.

Abstract: A color transformation method which accounts for colorant interactions includes establishing a plurality of tone reproduction curves (TRCs), for one or more of the color separations forming a digital image. Each TRC accounts for colorant interactions between a primary colorant with which the first color separation is to be rendered and at least one secondary colorant with which at least a second of the plurality of color separations is to be rendered. The TRCs include input values and their corresponding modified input values. In a given TRC, the input values of the second and optionally other color separations are fixed. For a pixel of the digital image having a given input values for the first and second color separation one or more of the TRCs are selected which bound the fixed input value for the second color separation and a modified input value is determined therefrom.

Abstract: Document processing systems and methods are presented for transforming color image data from an input color space to output color space using space filling interpolation to mitigate loss of color information at the corners of color gamuts. An initial interpolation of the input color space pixel values for each pixel is performed to compute initial output color space pixel values, and these are converted into luminance-chrominance color space pixel values. An adjustment value ? is then computed according to the luminance-chrominance color space pixel values, and final output color space pixel values are computed according to the initial output color space pixel values and the adjustment value ?.

Abstract: Systems and methods, including computer software products, for processing gray colors in a conversion between color spaces involve identifying a non-pure gray color value in a color space that represents a substantially gray color. The methods further include converting the non-pure gray color value to a corresponding pure gray color value in the color space. The methods also include determining a first difference vector between the non-pure gray color value and the corresponding pure gray color value. The methods further include determining a distance between the corresponding pure gray color value and a selected color value. The corresponding pure gray color value represents a nearest pure gray color value to the selected color value. The methods also includes determining a correction factor based on the first difference vector and the distance and applying the correction factor to the selected color value to produce a corrected color value.

Abstract: When text is taken in with a scanner, the reflection of the light from a sheet of paper, etc. causes a tinge on the sheet of paper. The tinge around each letter is printed as minute dots, and the outlines of printed letters are blurred and the clearness or distinctness of the letters are decreased. When printing text taken in through a scanner unit 30, by reducing (or reducing to zero) the ratios of occurrence of small dots in a gradient range “n” or “m” of the data for printing (CMYK signals) generated from image data (RGB signals), or converting such ratios of occurrence of small dots into the ratios of occurrence of large dots based on the weight ratio, the blur of each letter that may be caused by the small dots can be reduced, and the clearness and distinctness of each letter can be improved.

Abstract: The present invention is to provide an image processing system and the method thereof capable of maintaining gradient characteristics near a black point of an output image, when performing color matching in a color printer, even if a source profile has a lower minimum lightness value of output color gamut. In the present invention, when a condition is matched by comparing the minimum lightness points of the source profile and output color gamut, a correction color conversion table is generated by correcting the minimum lightness point of the output color gamut to a correction target value set in advance. Color conversion is performed for an input image using the correction color conversion table.

Abstract: A second printing control unit is provided. If the setting information is the information of setting for avoiding the use of Cl ink (uncolored ink), the second printing control unit refers to the same color conversion table as is used by a first printing control unit. Thereby the second printing control unit color-converts input image data into image data comprising gradation data corresponding to at least the amounts of colored inks in C, M, Y, R, V, and K consumed. The second printing control unit can carry out such control as to cause a printer (printing device) to use only the C, M, Y, R, V, and K colored ink and print a print image, using the image data.

Abstract: Systems and methods, including computer software products, for processing gray colors in a conversion between color spaces involve identifying a lookup table used to convert a color value from a first color space to a second color space. The method includes identifying a pure gray color value from a first plurality of color values, determining a corresponding pure gray color value in the second color space substantially equivalent to the pure gray color value from the first plurality, and replacing a corresponding non-pure gray color value with the corresponding pure gray color value. The method includes identifying near gray color values in the second plurality of color values that are located in relatively close proximity in the lookup table to the corresponding pure gray color value in the second color space. The method also includes modifying the lookup table by replacing the near gray color values using a smoothing function.

Abstract: An image forming apparatus including: an outputting section to output a chart which has a gradation pattern in a low-density area, the gradation pattern including patches, each of the patches having a density; a reading section to read-in the density of each of the patches; a calculating section to calculate, based on the density, an adjusting value to conduct a gamma correction; and an output adjusting section to conduct an adjustment of an output in the low-density area based on the calculated adjusting value.

Abstract: A color converter has a setting section, a determining section, and a converting section. The setting section sets the ratio between plural color rendering intents. The determining section determines a color conversion function for converting a first image signal in a first color space into a second image signal in a second color space different from the first color space, based on the ratio between the color rendering intents. The converting section converts the first image signal into the second image signal based on the color conversion function determined by the determining section.

Abstract: A spectral reflectance, corresponding to multiple quantities of coloring materials, is obtained, and a target spectral reflectance, corresponding to data of a color of interest, calculated based on the spectral reflectance. The target spectral reflectance is calculated in a manner that makes the spectral reflectance change contiguously, across an interval of multiple colors that are reproduced by the quantities of coloring materials in question. A decision of the quantities of coloring materials in question is thus made that corresponds to the target spectral reflectance.

Abstract: A method of converting a color image into a monochromatic image, includes converting the color image into a color space representing brightness values and attribute values of pixels constituting the color image, converting the color image into the monochromatic image based on the brightness values of the pixels, and modifying brightness values of pixels of the monochromatic image based on eigenvalues corresponding to the attribute values of the pixels of the color image.

Abstract: An output color is calculated from a fundamental stimulus value and a spectral support coefficient which indicate an input color using a calculation unit for calculating an output color corresponding to the input fundamental stimulus value and the input spectral support coefficient using a table whose inputs are a fundamental stimulus value and a spectral support coefficient. The interval of grid points of the table are uneven regarding the spectral support coefficient, and the interval in the vicinity whose relevant spectral support coefficient is zero is small as compared with the interval in the vicinity whose spectral support coefficient has a great absolute value.

Abstract: An image processing method for performing color conversion among a plurality of image forming apparatuses, includes the steps of: a) producing a plurality of color profiles provided for performing color conversion on input image information within a same color space or through different color spaces; and b) selecting one of the plurality of color profiles whereby color in an image formed by one of the plurality of image forming apparatuses may be approximately equal to color of an image formed by another of the plurality of image forming apparatuses.

Abstract: A color conversion table for converting M color signals of an input system into N color signals of an output system is disclosed. The color conversion table is prepared by and obtained based on a calculation target point corrected by moving a position of the maximum gradation of each fundamental color of the output system to a position of the maximum gradation of the fundamental color of the input system and on calculation target points corrected for gradations other then the maximum gradation of each fundamental color by moving positions of the gradations of the fundamental color in output system to the positions of the gradations of the fundamental color in the input system.

Abstract: The present invention relates to a color adjustment apparatus and a method thereof. The color adjustment apparatus according to the present invention includes a calculation unit and an adjustment unit. The calculation unit receives an input color signal, and divides the input color signal into color groups and performs a calculation operation thereon to generate at least two calculation signals. The adjustment unit receives the calculation signals and the input color signal, and adjusts at least one of contrast group and complement group of the input color signal according to at least two of the calculation signals and a predetermined color value to generate an output color signal for a video-display apparatus. Accordingly, viewers can enjoy better visual experience.

Abstract: An image processing apparatus of the present invention comprising (a) a first signal processing circuit for applying gamma correction to an n-bit (n: a natural number) digital signal inputted as a video signal and for converting the n-bit digital signal into an m-bit (m>n, m: a natural number) digital signal, and (b) a second signal processing circuit for adding a noise signal, which is used for pseudo contour reduction, into the m-bit digital signal from the first signal processing circuit and for outputting a Q-bit (Q: a natural number) digital signal, which is obtained from rounding off a less significant (m?Q) bit (Q?n) from the m-bit digital signal, to a display section.

Abstract: An image processing apparatus for converting inputted image data to image data in accordance with characteristics of an image forming unit, including: a first gradation correction unit which performs a gradation correction processing of the inputted image data in accordance with the characteristics of the image forming unit; a total toner amount control unit which performs a total toner amount control processing of the image data which has undergone at least the gradation correction processing executed by the first gradation correction unit; and a second gradation correction unit which performs a gradation correction processing in accordance with the characteristics of the image forming unit with respect to the image data which has undergone at least the total toner amount control processing executed by the total toner amount control unit.

Abstract: An apparatus for adjusting specific color attributes is provided. Wherein, the color space transforming unit receives a color input signal with R, G and B color attributes, and transforms it into a color middle signal with separated luminance (Y) and chrominance color attributes (Cb and Cr). The color controlling unit computes the hue of the color input signal to generate a hue signal and generates a hue signal, a saturation signal and an intensity fine-tune signal according to the hue signal, and computes the color input signal to generate an adjustment parameter and generates an adjusted saturation signal and an adjusted intensity fine-tune signal from the saturation signal and the intensity fine-tune signal according to the adjustment parameter. The color adjusting unit adjusts the color middle signal to output a color output signal according to the hue signal, the adjusted saturation signal and the adjusted intensity fine-tune signal.

Abstract: The present invention relates to a tone-conversion device for converting a tone of an image having an achromatic signal and a chromatic signal, and it includes the following components: a signal extracting unit defining an achromatic signal of a first pixel or a second pixel from plural pixels as an achromatic signal value, the second pixel being in an immediate neighborhood; a neighborhood processing unit generating a local signal of the first pixel according to the achromatic signal and the chromatic signal of a third pixel contained in the neighborhood area which is larger than the second pixel; a gain determining unit determining a conversion gain for the first pixel according to the achromatic signal value and the local signal; and a tone conversion unit performing tone conversion by multiplying the signal component of the first pixel by the conversion gain.

Abstract: An image processing apparatus configured to generate image data for forming an image using a plurality of color materials of similar colors and of different densities includes a gradation changing unit configured to conduct a gradation changing process for changing gradation of C, M, Y, and K signals of an image and a color separation unit configured to conduct a color separation process for separating color component data for a dark color material into color component data for a dark color material and color component data for a light color material. The gradation changing unit is configured to conduct the gradation changing process before the color separation unit conducts the color separation process.

Abstract: An image reading apparatus which is capable of preventing images read from a double-sided original from suffering an in-surface color irregularity on each of images read from the respective opposite sides of a double-sided original and a color difference between the front and reverse. A CCD line sensor reads a front-side original image. An image processing ASIC calculates shading correction data for performing shading correction on original image data read from the original image by the CCD line sensor, based on read luminance values obtained by the CCD line sensor by reading a plurality of halftone gradation patches thereon on a correction chart. The shading correction data calculated by the image processing ASIC is corrected based on read luminance values associated, respectively, with at least two of the gradation patches.

Abstract: An image signal processing apparatus includes the following elements. A control unit determines a gradation correction characteristic representing a conversion characteristic for correcting brightness of an input frame. A separation unit separates the determined gradation correction characteristic into a representative gradation correction value representing an amount of correction for a representative value of a main subject and a remaining gradation correction characteristic obtained by removing the representative gradation correction value from the gradation correction characteristic. A gain processing unit uniformly applies the separated representative gradation correction value to the frame as a gain. A noise reduction processing unit performs noise reduction processing on the frame to which the representative gradation correction value is applied.

Abstract: In a method and system for processing a photographic image having lightness values, L*, representing one of the colorimetric values of an original scene, the photographic image is transformed. The transformed image has a gamma as a function of CIE 1976 L*, which includes a dark region having a rising slope, a light region having a falling slope, and a plateau region having a slope constantly within 5 percent of a maximum value in said plateau region. The rising slope is at least twice as large as the absolute value of the falling slope. The plateau region is between 10 L* and 30 L* wide. Gamma is a derivative of visually perceived reproduced CIE 1976 L* versus scene CIE 1976 L*. Gamma has a maximum slope between 1.5 and 2.0.

Abstract: An image forming apparatus includes an image forming unit adapted to form images of a plurality of colors in a manner in which a predetermined pattern of a predetermined color is registered thereon and superimpose those images to form a color image, a controller configured to control the image forming unit so as to form a patch image of each color for density detection, and a detector configured to detect the density of each of the patch images. The controller controls the image forming unit so as to superimpose the predetermined pattern of the predetermined color upon the patch image of a predetermined color and not to superimpose the predetermined pattern of the predetermined color upon the patch images of the other colors.

Abstract: A one-dimensional LUT has been incapable of color matching. A three-dimensional LUT has been incapable of ensuring a color conversion accuracy enough to reproduce fine changes in color tone on a monochrome image. It has been impossible to suppress a storage capacity for a color conversion table by ensuring the accuracy. There is provided a color conversion table which has a plurality of pieces of reference color image data making correspondence between color data for a first image device and color data for a second image device and comprises a specified total information amount. The color conversion table is used to distribute the reference color image data over a prescribed area in a specified color space. Color data information for each reference color image data is increased more than a specified amount within a limit of the specified total information amount. Further, a color conversion table is created using an original table which highly accurately defines colors in part of the color conversion table.

Abstract: An image processing device includes an image generating unit configured to generate image data expressed a single hue from color image data, which include at least a first area to be filled with a first color based on first hue component data and a second area to be filled with a second color based on second hue component data, the first and second areas defining a boundary line by line contact or overlap therebetween, a density determining unit that determines a first density and a second density in the single-hue image data based on the first hue component data and second hue component data, respectively, a comparing unit that compares the first density with the second density, and a boundary generating unit that generates the boundary line with the single hue of a third density different from the first and second densities based on the comparison result by the comparing unit.

Abstract: A luminance nonuniformity adjustment module for eliminating luminance nonuniformities in light emitting elements determines a luminance correction coefficient for each light-emitting element through a test print. The luminance nonuniformity adjustment module comprises a provisional luminance correction coefficient calculation unit, an improper coloring degree calculation unit and a luminance correction coefficient determination unit. The provisional luminance correction coefficient calculation unit calculates a provisional luminance correction coefficient by comparing a measured density value for a grayscale chart and a predetermined target density value. The improper coloring degree calculation unit calculates an improper coloring degree, which is the degree of improper coloring that occurs when other colors are expressed when developing a specific color, from the measured density values for the grayscale chart and an unbalanced chart in which the gray balance has been altered.

Abstract: An image forming engine has color shifting amount storage units C, M, Y, and K (black) which store actual shifting amounts relative to ideal scan directions on image carriers C, M, Y, and K in image forming units C, M, Y, and K. Color shifting correction amount arithmetic units calculate color shifting correction amounts for respective color components to base on the stored color shifting amounts. Color shifting correction units C, M, Y, and K perform color shifting correction by converting coordinates upon reading out image data from bitmap memories C, M, Y, and K on the basis of the calculated color shifting correction amounts, and then perform tone correction. Data after tone correction undergo halftone processing by halftone processors. C, M, Y, and K to suppress moire. PWM processors C, M, Y, and K generate PWM signals for scanning, and output them to exposure units C, M, Y, and K of the respective image forming units.

Abstract: Embodiments of the present invention comprise systems, methods and devices for digital image contrast enhancement.

Abstract: Embodiments of the present invention comprise systems, methods and devices for digital image contrast enhancement.

Abstract: Saturation to white and fading of subjects' faces are prevented when performing density correction on digital images. An average signal value, obtained from a photographic image, is compared against a predetermined reference value, to judge whether correction is to be administered to brighten or darken the photographic image. A corrected image constituted by corrected signal values, which are obtained by correcting the pixel signal values of the photographic image with a predetermined correction amount, is generated only in cases that it is judged that correction to brighten the photographic image is to be administered. At this time, if the brightness represented by signal values of pixels of the photographic image are greater than or equal to a predetermined brightness, the correction amount is gradually reduced as the signal values become brighter.

Abstract: A color image processing apparatus includes: a minimum value selection unit that selects a minimum value of an input gray level values; a first calculation unit that calculates a generation amount of black; a second calculation unit that calculates an UCR amount which is a value relevant to the minimum value; a third calculation unit that outputs a correction coefficient value which is a value relevant to the minimum value; a subtraction unit that subtracts the UCR amount from each of the input gray level values to generate output; a multiplication unit that multiply the output of the subtraction unit by the correction coefficient value; a significant bit selection unit that selects a significant bit of a multiplication result; and a gray level correction unit that makes a gray level correction to the generation amount of black and the output of the multiplication unit.