Abstract: An image processing system comprises a first input unit for inputting an image signal, a second input unit for inputting a character or code signal, a binarizing unit for binarizing the image signal, including a unit for gray level processing the image signal, a discrimination unit for discriminating the presence or absence of a gray level in the image signal, and an output unit for outputting the image signal when the discrimination unit discriminates the absence of the gray level or the character or code signal as a digital image signal without processing the signal by the gray level processing unit.

Abstract: Device independent color signals in color coordinates of the calorimetric system are computed using the color signals Ci, Mi, Yi, Ki in first CMYK coordinates. A maximum quantity of black maxKi of the color signals Ci, Mi, Yi, Ki is computed by using the color signals Ci, Mi, Yi, Ki and the device independent color signals. A black ratio g of the color signals Ci, Mi, Yi, Ki is computed using the maximum black quantity maxKi and the color signal Ki. A maximum quantity of black that can be obtained without changing the device independent color signals is computed using the device independent color signals. The color signal Ko in second CMYK coordinates is determined by the maximum black quantity and the black ratio, and the color signals Co, Mo, Yo, Ko in the CMYK coordinates are determined by using the device independent color signals and the color signal Ko.

Abstract: A color mapping scheme is provided which enables a K-only black point while minimizing interpolator image artifacts. Specifically, a system and method of reducing image artifacts for a color imaging device include implementing a color map so that no C, M or Y color value that is used in defining the black point is produced, except at the black point. The system and method further include implementing a halftone ramp so that: (i) a halftone pattern is selected to provide no rendering for any C, M or Y color value that is used in defining the black point, and (ii) a halftone pattern is selected to provide a full rendering for any K color value that is used in defining the black point. The color map is also implemented so that no C, M or Y color value that is used in defining the black point is obtained as a result of interpolation, except for at the black point.

Abstract: A method and apparatus for printing a digital color images wherein the application of both colored inks and black ink to a common location is prevented to minimize ink usage, and to provide a more uniform distribution of black and colored pixels. Input pixel data is received at a first depth in terms of `c` bits per pixel, wherein `c` is an integer, for at least three color separations of a digital color image. Pixel data at the first depth of `c` bits per pixel is derived for a fourth separation of the digital color image based upon the pixel data of the three color separations. Error diffusion is performed on the pixel data of the fourth separation to redefine the pixel data at a second depth of `d` bits per pixel, where `d` is an integer and `d`<`c`.

Abstract: The system, method, and program of this invention is capable of taking as input a three dimensional colorant (e.g., CMY, L*a*b*) and determining an equivalent combination of colors made up of four or more colorants that are used by a given printer. A plurality of patches are printed having predetermined known combinations of varying percentages of three primary colors (e.g., CMY). Another set of patches are printed having predetermined varying percentages of a fourth color (e.g., black). The L*a*b* of these patches are measured. An inversion program is used to determine equivalent CMY component percentage values for the varying percentages of the fourth component based upon similar actually measured L*a*b* values. These determined CMY component percentage values and the known percentages of CMY are used to substitute the fourth colorant (K) for each of the original CMY combinations, known as fourth colorant substitution or black substitution.

Abstract: In a digital full color copying machine, image signals of red, green and blue are converted to a value signal, and histograms of the value signal for chromatic dots and achromatic dots respectively are generated. Then, a document type, such as a color standard document, a color photograph document, a color standard document having a colored background, a black-and-white standard document, or a black-and-white photograph document, is determined automatically based on the histograms. Background level of a copy is controlled automatically at an appropriate level both for a color document and for a black-and-white document having a white background according to the document type by gradation correction of the value signal. Thus, background processing is performed irrespective of a color document or a black-and-white document.

Abstract: This invention relates to an image processing apparatus. A black data generator of the image processing apparatus is operated such that a calculator solves the equation (1) using a maximum value, max(C,M,Y), detected by a maximum value detector, a minimum value, min(C,M,Y), detected by a minimum value detector, and a coefficient .beta. as parameters to output a black weight indicia .alpha. for black data:.alpha.-1-{max(C,M,Y)-min(C,M,Y)}/.beta. (1)A multiplier solves the equation (2) to output a value K for the black data:K=.alpha..multidot.min(C,M,Y) (2)Then, a character UCR converter, a photography UCR converter, and a halftone dot UCR converter output an output value BK for the black data corresponding to the value K as address data.

Abstract: A color correction unit for natural images, graphics and characters performs color correction of enlarging regions corresponding to primary colors (R (red), G (green) and B (blue)) and secondary colors (C, M and Y) while maintaining gray balance for R0, G0 and B0 raster image data representing an input object image, to generate C1, M1, Y1 and K1 multivalue density data. A binary-coding processing unit performs binary-coding processing of the C1, M1, Y1 and K1 multivalue density data to generate C2, M2, Y2 and K2 binary density data, and transfers the generated density data to a printer using a centroparallel interface or the like.

Abstract: When an image from a scanner or an external apparatus is to be printed out, in order to achieve both high color reproducibility and high gray reproducibility, a black signal is extracted from an input color image signal, the ratio of the extracted black signal to the color image signal is changed in accordance with an input instruction, and an output operation is performed in accordance with the extracted black signal and the color image signal. When a color image signal is formed by scanning an image, a black signal is extracted from the color image signal, a high-frequency component of the extracted black signal is removed, and an output operation is performed in accordance with the black signal, from which the high-frequency component is removed, and with the color image signal.

Abstract: An image processing apparatus and method are adapted to prevent a decline in image quality while reducing the number of bits in a discrimination signal stored in memory. The apparatus includes an image compressing device for encoding image data in prescribed block units and then storing the encoded data in a memory, after which the stored image data is decoded and outputted. A black-character discriminating unit discriminates a plurality of attributes of the image data, and a black-character compressing device encodes the plural results of discrimination in conformity with the image processing. The plurality of codes are divided into blocks of different sizes in such a manner that resolution is reduced, and the codes are stored in memory. Thereafter, the stored codes are decompressed and sent to a masking UCR circuit and to a spatial filter. On the basis of the codes sent, the masking UCR circuit and spatial filter apply image processing to the image data outputted from the image compressing device.

Abstract: A method is described for printing a colorant controlled neutral black object in a bitmap-based digital color printing system. The method is useful in systems where the black colorant is not sufficiently opaque to hide non-neutral combinations of non-black colorants mixed into the black color. Black colors in a color printing system can be composed either of black colorant only or of black plus non-black colorants such as cyan, magenta, and yellow. If the non-black colorants are not mixed in nearly equal quantities, they will add hue to the black color. A sufficiently opaque black colorant can hide this objectionable non-black hue. However, in cases where the black colorant is not opaque enough, it is important to use equal or nearly equal combinations of cyan, magenta, and yellow so that little net hue will be introduced into the black color. Equally important in some printing systems is the ability to control the amount of total colorant used in forming a process black color.

Abstract: A color image transmission apparatus designed for suitable color image processing in accordance with characteristics of a transmitting terminal has a processor for processing input color image data, and a controller for controlling the processor according to a protocol for communication with the transmitting terminal by using non-standard functions on a session layer in the protocol.

Abstract: The invention is directed to providing a saturation compensation technique for color printing that compensates for the over or under reduction of colorant levels that can result from gray component replacement (GCR) or under color removal (UCR) techniques. To solve the problems associated with the prior art GCR/UCR systems, embodiments of the invention implement a saturation compensation technique such that an overreduction of colorant levels is compensated for by increasing the color components (e.g., C, M and Y color components) of a color model accordingly. The saturation level that has been reduced to below a threshold TAC value can be increased to define richer looking, denser images. Embodiments of the invention determine the amount of the increase that is used to achieve a level of saturation that does not exceed the threshold TAC value. Alternatively, if there is an insufficient reduction of colorant levels such that the combined colorant levels (e.g.

Abstract: A color-image reader reads a recorded color image from a recording medium, and has an image sensor for sensing the color image as at least a first and second regular series of monochromatic image signals during a regular reading operation. A first optimal exposure period is determined regarding the first regular series of image signals, and a second optimal exposure period is determined regarding the second regular series of image signals. A first set of color-correction parameters is determined based on a first provisional series of image signals, sensed from the color image by the image sensor over the first optimal exposure period. A second set of color-correction parameters is determined based on a second provisional series of image signals, sensed from the color image by the image sensor over the second optimal exposure period. A color balance is performed among the first and second regular series of image signals by using the first and second sets of color-correction parameters.

Abstract: In an image forming apparatus, a black edge of a document image is emphasized, and the black edge is detected by deciding an edge from the lightness data and by deciding a black color from the chroma data. The data of cyan, magenta and yellow of a pixel at a black edge are replaced with minima of data of cyan, magenta and yellow of pixels in a prescribed region around the pixel. In order to prevent erroneous decision of a black edge, if a number of isolated pixels is larger than a threshold level, a decision as a pixel at a black edge is invalidated. Automatic exposure can be performed on a color document for correcting a background of the document obtained in a prescan. The background level of the document is determined only on pixels decided to be black. When color balance is adjusted on one of the data of cyan, magenta, yellow and black, the density is kept constant.

Abstract: A system, method, and program of the invention determine a unique combination of four colorants (C'M'Y'K') of a given printer that is equivalent to an externally defined four colorant combination (CMYK) by having the same color values (e.g., L*a*b* values). L*a*b* values associated with each three component combination (CMY) with the fourth component value (K) equal to zero of the externally defined four colorant combination (CMYK) are used in an inversion/interpolation program The printer also prints out a matrix of predetermined varying combinations of the three colorants of the printer (CMY)p with the fourth colorant K equal to zero. L*a*b* values are measured for each patched. These values and the corresponding three colorant combination values are inputted into the inversion/interpolation program.

Abstract: An image processing system is constructed of an input device for inputting color image data which does not include color components corresponding to specific colors' a storing media for storing a table for making the color image data which does not include the color components corresponding to the specific colors correspond to output image data constructed of color components corresponding to the plurality of recording materials including the specific colors' and a developing unit for developing the input color image data into output image data constructed of the color components corresponding to the plurality of recording materials including the specific colors by using the table. The developing unit executes the developing process by using an interpolating process according to the kinds of color components corresponding to the recording materials.

Abstract: A method for undercolor removal (UCR) from a multi-color image represented by N color planes of non-black pixel image color values and replacement of removed undercolor by black values, includes the following steps. A corrected black color plane is obtained by replacing initial maximum black color values with black color values that are a Min function between the initial black color values and N-1 logically corresponding non-black pixel image color values. Page strip portions of the corrected black color plane are then revised so that each pixel black color value thereof is converted to a UCR value by deriving the Min function with logically corresponding, Nth color plane non-black pixel image color values. Next, logically corresponding UCR values for each page strip are subtracted from Nth color plane non-black pixel image color values and each page strip from the Nth color plane is passed to a print engine for rendering.

Abstract: An image processing apparatus which converts a color region in an input color image into predetermined images corresponding to colors. The apparatus has a discriminator for discriminating the colors in the input color image, a converter for converting the color regions in the color image into the predetermined images corresponding to the colors discriminated by the discriminator, and a generator for generating the predetermined images and character images representing the colors corresponding to the predetermined images.

Abstract: Hue, lightness, and saturation signals are obtained from an input signal, and hue direction intensity signals with respect to respective unit colors are determined using color corrective intensity functions for respective hues which have been established based on measured values. These hue direction intensity signals are multiplied into corrected intensity signals with respect to the respective colors, which are multiplied by desired correction coefficients. Resulting product signals for the respective unit colors are added into corrected signals with respect to given color signals.

Abstract: A color image forming apparatus having a function for duplicating an image in two desired colors. A color of an image of an original document is read into color elements of a red (R), a green (G), and a blue (B) color, represented by corresponding image signals R, G, and B, respectively. The image processing unit distinguishes between a first case that the read color is a chromatic color and a second case that the read color is an achromatic color. When the color is distinguished as a chromatic color, the image processing unit converts the color into one of two predetermined colors, each defined by color elements C, M, Y, and K corresponding to image signals C, M, Y, and K, respectively. When the color is distinguished as an achromatic color, the image processing unit converts the color into the other one of the two predetermined colors.

Abstract: This is a method for adjusting output device profiles for four-color devices such as offset presses. The user of this invention starts by selecting a base profile. This base profile produces satisfactory color but does not have the desired amount of Gray Component Replacement (GCR). The user of this invention makes use of this invention to adjust the GCR of the output profile until it is at some desired level. The invention then produces a new output profile which produces the same color as the base profile but which has the desired degree of GCR.

Abstract: In recording a received image in an image communication apparatus, there is discriminated whether the received image is to be recorded as a color image or as a monochromatic image, then determined, according to the result of the discrimination, which of plural recording members is to be supplied, also the mutually different plural recording members are selectively supplied according to the determination, and the received image is recorded on thus supplied recording member. In this manner it is rendered possible to preferentially select an optimum recording member for monochromatic image recording and another for color image recording, thereby improving the image quality in case of color image recording and reducing the running cost in case of monochromatic image recording.

Abstract: An image having suitable color-tone and density is formed on a recording medium so that a full-color image of an excellent color-tone depending on a OHP can be projected, wherein a CCD separates colors of an original image to read it for converting into a RGB digital signal by an A/D conversion circuit, the process corresponding to a required image signal forming condition is executed by image process means for the digital signal to generate an image signal for outputting it to an LD driver, and a full-color image forming apparatus for forming a color image on a recording medium utilizing plural kinds of color materials based on the image signal comprises the image processing means for executing a gradation conversion process for the signals of C, M and Y in a LUT 1 circuit and executing a different gradation conversion process for a black signal Bk in a LUT 2 circuit different from a LUT 1 circuit.

Abstract: A test image 40 for determining a gamma value has a plurality of first gradation patterns 20 and a plurality of second gradation patterns 30. The patterns 20 and 30 are arranged alternately in a vertical direction. In each pattern 20, a relative brightness linearly increases from left to right. In each pattern 30, a relative brightness linearly decreases from left to right.

Abstract: During a black-and-white image reading mode, for each picture element, outputs from at least two of the light receiving elements of the R, G, and B light receiving elements are added together into color sum data. Whether the picture element presents black or white is determined based on the sum data.

Abstract: Color space models are developed using designed experiments of pigment and binder ratios of a plurality known paint formulations for correlating color coordinates in a three-dimensional color space and paint constituents. Capabilities of the paints are determined by limits placed upon the constituents. Each color space model is used to return respective constituent apportionments for achieving predetermined color coordinates. Constituent apportionments within the respective limits correspond to paint formulations within the color space capability of the corresponding known paint formulation. When all such respective constituent apportionments are within the respective limits for each known paint formulation, the predetermined color coordinates are achievable and within a common color space capability of the known paint formulations.

Abstract: A system for converting original RGB color signals to CMY signals includes the step of separating color signals from the original image into low-frequency and high-frequency components. The low-frequency components are converted to CMY signals via a look-up table reflective of a non-linear algorithm, while the high-frequency components are converted to CMY signals according to linear algorithms. The technique avoids color distortion caused by high-frequency noise, such as from halftone screens, in the original image.

Abstract: A color facsimile apparatus for color-recording color image data received by facsimile communication onto a predetermined recording sheet. When a facsimile receiving operation is performed under a predetermined condition, the color facsimile apparatus sends a protocol signal to the sending facsimile apparatus, the protocol indicating that the receiving capability of the color facsimile apparatus is for receiving monochrome image data. Also disclosed is an image communication apparatus for color-printing color image data received by image data communication onto a predetermined recording sheet. When reception of image data is performed under a predetermined condition, the received color image data are converted to monochrome image data on which predetermined processing is performed.

Abstract: A method and system for determining an equal amount of a plurality of color densities to be removed in rendering a multicolor image using a black toner and the plurality of colored toners. The rendering of the multicolor image is executed with a multicolored digital inputs according to undercolor removal techniques. The includes providing a black toner coverage bit count and a total colored toner coverage bit from a plurality of colored toners (often cyan, magenta and yellow) to be used in rendering the multicolored image. The black toner and colored toner coverage estimations are summed; if this sum exceeds a predetermined maximum total toner density level, an equal amount R of toner to be removed from each colored toner separation is determined by subtracting the predetermined maximum from the sum of the black and colored toner estimations, and then dividing the result by the number of colored toner used to produce gray (again, usually 3-cyan, magenta and yellow).

Abstract: There is provided an image processing apparatus constructed by an input device for inputting image data constructed by a plurality of color components, a restriction processing unit for executing a restricting process for restricting so as not to exceed a predetermined value for the image data constructed by the plurality of color components so that a quantity of each recording material which is used in an image recording unit doesn't exceed a predetermined quantity and an output device for outputting the image data subjected to the restricting process to the image recording unit, wherein the restriction processing unit processes on the basis of the predetermined value according to a feature of the input image data.

Abstract: The present invention relates to an image processing apparatus and a method of forming an image by separating color information into two or more color information items. The boundary of images is compensated, the images being the images formed by an analog recording system for forming an image on a recording medium by removing a predetermined color component from an original document image and a digital recording system for forming an image on said recording medium by extracting a predetermined color component from said original document image. Therefore, if a slight positional deviation takes place between images formed by the analog recording system and the digital recording system, a want of color information can be prevented. Therefore, the deviation can be satisfactorily compensated so that an original image can be correctly reproduced.

Abstract: In color graphics printing, incompatible inks, such as true black and color inks, tend to bleed across color field boundaries. Moreover, in four-color systems, there is a discontinuity in the physical color gamut, as distinguished from the logical color gamut, associated with the redundant color. A method is disclosed for alleviating both problems by adjusting image data prior to dithering. The method slightly shifts the logical color indicated in the image data so as to avoid the discontinuity that arises with neutral colors. Preferably, in a four-color printing system, yellow is depleted in the image data, so that after dithering, more dots of blue ink are printed in a given area than would be printed otherwise. For each pixel, the amount of correction is inversely related to the color saturation. The presence of blue ink dots within the substantially black field reduces bleed along the field edges.

Abstract: An image processing apparatus includes a first input unit which scans an original image and generates a first image signal, and a second input unit which inputs a second image signal from an external apparatus. An edition unit performs an edition by combining the first and second image signals, and a color gamut mapping device performs a color gamut mapping on an input image signal. An image forming device forms a color image according to the color gamut mapped image signal, wherein the edition is executed by the edition unit before the color gamut mapping is performed by the color gamut mapping device.

Abstract: A computer product for controlling a color-reproduction process employing N colorants, where N is greater than 3, the computer program product comprises: a computer readable storage medium having a computer program stored thereon for performing the steps of: defining a first transformation from a N-dimensional colorant-signal space associated with the color-reproduction process to a 3-dimensional colorimetric space such that each combination of N colorant signals is mapped to a visual color that would be produced by the process in response to that combination of signals; defining a second transformation for mapping from a 3-dimensional parameter space into the N-dimensional colorant-signal space for defining a particular 3-dimensional subspace of the N dimensional colorant-signal space for ultimately restricting the permitted combinations of the N colorant signals; combining the first and second transformations for defining a third transformation for transforming data directly from the 3-dimensional parameter

Abstract: A digital image of a document having chromatic and achromatic colors is read, and an edge of a black character is discriminated. Further, an outside area and an inside area of the edge are detected. Edge emphasis is performed on an inside area of the edge for data of achromatic colors. On the other hand, data of chromatic colors in an inside area of the edge is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel. Data of chromatic colors and of achromatic colors in the outside area is substituted with a minimum data of the pixel under interest and pixels surrounding the pixel.

Abstract: A bitmap-based digital color printing method and system is described which automatically detects when a black object is commanded to be printed, and changes the Bit Block Transfer (BitBlt) method so that the resultant composition of the black color at each point in the bitmap is responsive to the amount of non-black colorants already existing in the background color at that position on the page. For many printing systems the resulting prints exhibit fewer visual defects. Single-color black objects printed on top of a color field are printed as process black responsive to the background color. Therefore, they exhibit a greater density and gloss and show fewer problems caused by the misregistration of separations or other printer defects, such as white fringes around the black objects. They also avoid problems caused by excessive ink coverage differences between foreground black and background color.

Abstract: A bitmap-based digital color printing method and system is described which automatically detects when a black object is to be printed and changes the Bit Block Transfer (BitBlt) method so that the black color becomes a mixture of black plus the background colorants, limited by an allowed maximum non-black value for each separation. More specifically, the process determines, for each non-black separation, a maximum allowable amount to be used in black printing, reads the existing background color bits, and clips them if necessary to the allowed maximum before mixing them into the black color. The result will be a limitation on the total colorant amount of the black area, which improves some printer defects caused by too much colorant. The clipping can be accomplished at the bit level during the read-modify-write process if both the maximum and actual colors are represented with the same monotonic halftone dot specification, and are ANDed together to form the clipped bits.

Abstract: In reproducing an input RGB (red, green, and blue) color defined by particular tristimulus values by CMYK (cyan, magenta, yellow, and black) ink, color samples having a plurality of colors at controlled amounts of CMY (cyan, magenta, and yellow) with respect to a plurality of different amounts of K (black) ink are measured to be used as an original CMYK color reproduction zone. The original CMYK color reproduction zone is divided into individual CMYK color reproduction zones for each respective amount of the K ink. The individual CMYK color reproduction zones are memorized. All of the individual CMYK color reproduction zones are searched in response to the input RGB color defined by the particular tristimulus values to obtain at least one set of the amounts of the CMYK ink corresponding to the input RGB color. When a plurality of sets of the amounts of the CMYK ink are obtained, there sets are memorized as memorized sets of the amounts of the CMYK ink.

Abstract: An image processor is provided which emphasis-processes an image to be copied with attention to the detection of black edges so that clear color copy outputs are obtained. R, G and B data read out from an original by a scanner are converted into C, M and Y complementary color data by a complementary color reversing circuit. The complementary color data are transmitted to a black edge processing circuit and to a black edge detecting circuit. The black edge detecting circuit detects the inside or the outside of a black edge, and in accordance therewith, the black edge processing circuit, for example, changes the coefficient of a spatial filter. The output of the black edge processing circuit is outputted to a printer through a black generating circuit, a tone correcting circuit and a half tone processing circuit.

Abstract: Described is a method and a device for converting a color signal consisting of a plurality of chromatic color components into another color signal consisting of the plurality of chromatic color components and an achromatic color component. Firstly, an achromatic value is obtained, and then an under color addition is executed to obtain a chromatic value for each of the plurality of chromatic color components. Then, whether the chromatic values for the plurality of chromatic color components should be replaced with predetermined values is examined. If it is determined that the chromatic values for the plurality of chromatic color components should be replaced with predetermined values, the chromatic values are replaced with the predetermined values, and the another color signal consisting of the chromatic color components having the chromatic values and the achromatic color component having the achromatic value is output as the converted signal.

Abstract: Three-dimensional LUTs produce a lightness signal L* from input color signals C, M and Y. The three-dimensional LUTs are respectively provided for four divisional sections of an input color signal K. A three-dimensional LUT switching device judges to what section a current value of the input color signal K belongs. A selector selects one of the LUTs in accordance with a judgment result. Similar processing is performed for chromaticity signals a* and b*. According to another aspect of the invention, three-dimensional LUT color converters produce color signals L.sub.2 *, a.sub.2 * and b.sub.2 * based on only input color signals C, M and Y. A position in the L*a*b* space of the color signals L.sub.2 *, a.sub.2 * and b.sub.2 * has a deviation from a position of color signals L.sub.1 *, a.sub.1 * and b.sub.1 * to be output actually. Based on an input color signal K, a one-dimensional LUT produces a lightness signal L.sub.3 *, which corresponds to the deviation.

Abstract: An image forming apparatus which varies the blending ratio by which color-seperated image signals are blended together to form a monochromatic image. The apparatus inputs a plurality of image signals which have been color-separated, and synthesizes the plurality of image signals by blending to form a monochromatic image. A density regulating mechanism regulates the density of the monochromatic image to a predetermined density level, and the apparatus varies the blending ratio of the synthesized plurality of image signals based on the predetermined density level.

Abstract: A system of transmitting and receiving image data comprising a number of pixel data, such as color copying machine or the like, comprises producing image control data regarding the image data to be transmitted on a transmission side; transmitting pixel data of n colors for a period of time when the pixel data of (n+m) colors (n and m are positive integers) can be sequentially transmitted and transmitting the image control data for a period of time when the pixel data of n colors is not transmitted in the period of time when the pixel data of (n+m) colors can be transmitted; producing the pixel data of (n+m) colors on the basis of the pixel data of n colors on a reception side; and executing an image process to the pixel data of n colors or the pixel data of (n+m) colors on the basis of the image control data.

Abstract: With the present invention, an inputted color image is separated to image signals for three colors of Red, Green and Blue, determination is made as to whether a remarked pixel is for a specified color or not according to the image signals for the separated three colors, brightness data for the inputted color image is detected, determination is made as to whether a remarked pixel is for a white color or a black color depending on the detected brightness data, a pixel determined as for a specified color is converted to a specified color, and a pixel determined as not for a specified color is converted to a white color or a black color according to a result of determination as to whether the remarked pixel is for a white color or a black color, so that a separation area for a specified color can clearly be defined.

Abstract: Density data for reproducing an image using the four colors yellow, magenta, cyan and black is based on image data pertaining to chroma, luminosity and hue. The density ratio of two color components, from the three colors yellow, magenta and cyan, is first determined for a given hue. This ratio is then maintained constant while the color value for desired chroma and luminosity is determined. Finally, the density value for black is determined to reproduce a desired color. If the desired color lies outside a reproducible color gamut, a substitute color is chosen which has the same luminosity and hue as the desired color, and the maximum reproducible chroma within the gamut.

Abstract: The CiMiYi signals of input CiMiYiKi signals are converted into CoMoYo signals of CoMoYoKo signals by using three-dimensional LUT color converting devices. The Ki signal of the input CiMiYiKi signals is subjected to gradation conversion to obtain the Ko signal of the CoMoYoKo signals by using a one-dimensional LUT.

Abstract: An image processing apparatus for converting a color image into an image of an N (N=2, 3, . . . ) number of colors, i.e., black and other colors, is disclosed. In the image processing apparatus, a gray-component extracting unit extracts a gray component signal from input color image signals, and produces remaining-color-component signals. A black signal generating unit generates a black signal by using the gray component signal and the remaining-color-component signals. A color signal generating unit generates a color signal by using the remaining-color-component signals.

Abstract: A color image is by an optical scanner for conversion into three primary color data corresponding to the respective densities of the three primary colors. An edge detector detects a pixel of an edge based on the three primary color data. A pixel color judging device judges a color of a target pixel based on the three primary color data of the target pixel and its adjacent pixels. Based on edge detection results of the edge detector and pixel color judgment results of the pixel color judging device, detected is a pixel of a black edge. Judgement conditions for the pixel color judgement are established based upon characteristics that depend upon the order of arrangement of color filters in a scanner.

Abstract: An image processing apparatus includes an input device for image data, a discriminating device for discriminating a type of an image represented by the image data, a setting device for setting a discrimination standard of the discriminating device, and a display for displaying a condition of the setting device.