Color converter

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to a color conversion device that inputs a color image signal, converts it into color image data for image formation, and outputs it. More specifically, the input color image outside the color reproduction range (gamut) of the image formation device is input. The present invention relates to a color conversion device for outputting substantially the same color.

【0002】

[Conventional technology]

Conventionally, a memory map is known as a color conversion device that performs color correction of a color image signal or the like. As reference technical documents related to the color conversion device using this memory map, for example, first, "Signal interpolation method in memory device" disclosed in Japanese Patent Publication No. 58-16180, and second, JP-A-5. There are "interpolation method and color correction method" disclosed in Japanese Patent Application Laid-Open No. 75848, and thirdly, "color conversion device" disclosed in Japanese Patent Application Laid-Open No. 5-284346.

【0003】

In the first method described above, a unit cube, which is a basic solid in a three-dimensional color signal space, is set in the interpolation process, the unit cube is divided into a plurality of tetrahedrons, and the points to be corrected are eventually corrected. It is determined whether the tetrahedron is the tetrahedron, and correction calculation is performed from the output signals at each vertex of the discriminated tetrahedron.

【0004】

Further, in the second method, the XYZ space is divided into a plurality of triangular prisms, and one triangular prism containing the given X, Y, Z coordinates is selected from the plurality of triangular prisms, and the selected triangular prism is selected. It interpolates the output value set in the triangular prism.

【0005】

Further, in the third device, one cube or rectangular parallelepiped in the three-dimensional color space is divided into regions of powers of 2, and color conversion is performed.

【0006】

[Problems to be Solved by the Invention]

However, in the conventional color conversion device and its method as shown above, when the input color space is compressed to the color reproduction range of the image forming device, the input outside the color reproduction range of the image forming device is received. The color output from the image forming apparatus is far from the input color, that is, there is a problem in color reproducibility at the input outside the color reproduction range.

【0007】

In addition to the above, there are the following problems. That is, first, if the input color space is subdivided and the number of grid points is increased, the processing time for calculating the output value on the grid points becomes enormous. If is distorted, high-precision color conversion cannot be performed by reducing the number of divisions in the input color space. Third, when compressing the input color space into the color reproduction space of the image forming apparatus, the compression conditions can be freely adapted. Fourth, the entire color space near and outside the outermost color reproduction area cannot be compressed, and fifth, the optimum entire color space corresponding to the input color image cannot be compressed. There was a problem that it took a long time to calculate the output value on the unused grid points, and sixth, the user could not set it accurately while monitoring the actual output color.

【0008】

The present invention has been made in view of the above, and it is possible to output as much as possible color even for an input outside the color reproduction range of the image forming apparatus, and the input color space is subdivided into a grid. The first purpose is to efficiently calculate the output value on the grid points even when many points are taken.

【0009】

Further, the present invention enables the output of the same color as possible even for an input outside the color reproduction range of the image forming apparatus, and when the color reproduction area shape of the image forming apparatus is distorted, the input color space The second purpose is to realize highly accurate color conversion even when the number of divisions is small.

【0010】

Further, the present invention enables the output of as much equivalent color as possible even for an input outside the color reproduction range of the image forming apparatus, and when the input color space is compressed into the color reproduction space of the image forming apparatus, the present invention is used. The third purpose is to make it possible to accurately change the compression parameters such as the compression direction and the compression ratio each time.

【0011】

Further, the present invention enables the output of the same color as possible even for the input outside the color reproduction range of the image forming apparatus, and in addition to the compression near and outside the outermost part of the color reproduction area, the compression of the entire color space. The fourth purpose is to make it possible to set the rate and so on.

【0012】

Further, the present invention makes it possible to output as much as possible color even for an input outside the color reproduction range of the image forming apparatus, and efficiently compresses the entire optimum color space corresponding to the input color image. The fifth purpose is to make it possible.

【0013】

Further, the present invention makes it possible to output as much as possible color even for an input outside the color reproduction range of the image forming apparatus, and the user can accurately compress the input color space while observing the actual output color. The sixth purpose is to make it configurable.

【0014】

[Means for solving problems]

In order to achieve the above object, in the color conversion device according to claim 1, the output value of the color image forming device in an arbitrary three-dimensional input color space is divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating the grid point output values set for the grid points on the color space, it is determined whether or not the grid points are included in the color reproduction range of the color image formation difference. Then, in the first case where the grid points are within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and in the second case where the grid points are outside the color reproduction range. In addition, a calculation means for calculating grid point output values by simulating inputs outside the color reproduction range of the color image forming apparatus and in the vicinity thereof so as to correspond to the input / output relationship of the color image forming apparatus is provided. Is.

【0015】

Further, in the color conversion device according to claim 2, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, it is determined whether or not the grid point is included in the color reproduction range of the color image forming apparatus, and the grid point is the said. In the first case of being within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and in the second case where the lattice point is outside the color reproduction range, it is on the lattice point. Using the output value as a variable and using the input / output data of the color image forming apparatus for inputs outside and near the color reproduction range of the color image forming apparatus, so that the reproduction error (color difference) of the entire color conversion result is minimized. It is provided with a calculation means for calculating the grid point output value by varying the output value on the grid point as a variable.

【0016】

Further, in the color conversion device according to claim 3, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. The second storage means for storing a plurality of patterns of output values on lattice points outside the color reproduction range of the image forming apparatus and the lattice points on the three-dimensional input color space are the color reproduction area of the color image forming apparatus. In the first case where the grid points are within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and the grid points are the colors. In the second case, which is outside the reproduction range, the inputs outside the color reproduction range of the color image forming apparatus and its vicinity are simulated so as to correspond to the input / output relationship of the color image forming apparatus, and the grid point output values are set respectively. A calculation means for calculating is provided, and any pattern stored in the second storage means and grid point information stored in the first storage means are read out, and the grid points calculated by the calculation means are read. Color conversion is performed based on the output value.

【0017】

Further, in the color conversion device according to claim 4, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. The second storage means for storing a plurality of patterns of output values on lattice points outside the color reproduction range of the image forming apparatus and the lattice points on the three-dimensional input color space are the color reproduction area of the color image forming apparatus. In the first case where the grid points are within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and the grid points are the colors. In the second case, which is outside the reproduction range, the output value on the grid point is used as a variable, and the input outside the color reproduction range of the color image forming apparatus and its vicinity is used as the input / output data of the color image forming apparatus as a whole. The second storage is provided with a calculation means for calculating each grid point output value by varying the output value on the grid point as a variable so that the reproduction error (color difference) of the color conversion result is minimized. Any pattern stored in the means and the grid point information stored in the first storage means are read out, and color conversion is executed based on the grid point output value calculated by the calculation means. ..

【0018】

Further, in the color conversion device according to claim 5, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. A second storage means for temporarily storing output values on lattice points outside the color reproduction range and partly within the color reproduction range of the image forming apparatus, and a desired lattice point from the lattice points belonging to the color reproduction area. The selection means for selecting and selecting the processing method for the lattice points, the third storage means for storing the processing information selected by the selection means, and the lattice point information selected by the selection means are stored in the first. Read from the storage means of 3, determine whether or not it is included in the color reproduction region of the color image forming apparatus, and in the first case where the lattice points are within the color reproduction region, the actual color image forming apparatus. In the second case where the input / output relationship is simulated and the grid points are outside the color reproduction range, the input outside the color reproduction range of the color image forming apparatus and its vicinity is input to the input / output of the color image forming apparatus. The first storage means and the second storage means are provided with a calculation means for calculating each grid point output value by simulating so as to correspond to the relationship and storing the grid point output value in the second storage means. The stored grid point information is read out, and color conversion is executed based on the grid point output value calculated by the calculation means.

【0019】

Further, in the color conversion device according to claim 6, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. A second storage means for temporarily storing output values on lattice points outside the color reproduction range and partly within the color reproduction range of the image forming apparatus, and a desired lattice point from the lattice points belonging to the color reproduction area. The selection means for selecting and selecting the processing method for the lattice points, the third storage means for storing the processing information selected by the selection means, and the lattice point information selected by the selection means are stored in the first. Read from the storage means of 3, determine whether or not it is included in the color reproduction region of the color image forming apparatus, and in the first case where the lattice points are within the color reproduction region, the actual color image forming apparatus. In the second case where the input / output relationship is simulated and the grid point is outside the color reproduction range, the output value on the grid point is used as a variable, and the color image forming apparatus is outside the color reproduction range or in the vicinity thereof. Using the input / output data of the color image forming apparatus as the input, the output value on the grid point as a variable is changed so that the reproduction error (color difference) of the entire color conversion result is minimized, and the grid point output is performed. It is provided with a calculation means for calculating each value, reads out the grid point information stored in the first storage means and the second storage means, and colors based on the grid point output value calculated by the calculation means. It is the one that performs the conversion.

【0020】

Further, in the color conversion device according to claim 7, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. A second storage means for temporarily storing output values on lattice points outside the color reproduction range and partly within the color reproduction range of the image forming apparatus, and processing information of the lattice points within the color reproduction range of the color image forming apparatus are temporarily stored. A plurality of third storage means for temporarily storing the information of the input color image signal, a fourth storage means for temporarily storing the information of the input color image signal, and a plurality of image data stored in the fourth storage means. Detects which region of the input color space divided into regions, counts the number of pixels for each region to create a color map, and compares the color map with the color reproduction region of the color image forming apparatus. Among the grid points outside the color reproduction range, the grid points required to output the input image are selected, the grid points are stored in the third storage means, and the grid points are the color image forming apparatus. In the first case where the grid points are within the color reproduction region, the actual input / output relationship in the color image forming apparatus is simulated, and the grid is determined. In the second case where the points are outside the color reproduction range, the grid points are simulated so that the inputs outside the color reproduction range of the color image forming apparatus and its vicinity correspond to the input / output relationship of the color image forming apparatus. A calculation means for calculating each output value and storing the output value in the second storage means is provided, and the grid point information stored in the first storage means and the second storage means is read out and the calculation is performed. The color conversion is executed based on the grid point output value calculated by the means.

【0021】

Further, in the color conversion device according to claim 8, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. A second storage means for temporarily storing output values on lattice points outside the color reproduction range and partly within the color reproduction range of the image forming apparatus, and processing information of the lattice points within the color reproduction range of the color image forming apparatus are temporarily stored. A plurality of third storage means for temporarily storing the information of the input color image signal, a fourth storage means for temporarily storing the information of the input color image signal, and a plurality of image data stored in the fourth storage means. Detects which region of the input color space divided into regions, counts the number of pixels for each region to create a color map, and compares the color map with the color reproduction region of the color image forming apparatus. Among the grid points outside the color reproduction range, the grid points required to output the input image are selected, the grid points are stored in the third storage means, and the grid points are the color image forming apparatus. In the first case where the grid points are within the color reproduction region, the actual input / output relationship in the color image forming apparatus is simulated, and the grid is determined. In the second case where the points are outside the color reproduction range, the output value of the grid points is used as a variable, and the input / output data outside the color reproduction range of the color image forming apparatus and its vicinity is used as the input / output data of the color image forming apparatus. The first storage means is provided with a calculation means for calculating the grid points as variables and storing them in the second storage means so that the reproduction error (color difference) of the entire color conversion result is minimized. The grid point information stored in the means and the second storage means is read out, and color conversion is executed based on the grid point output value calculated by the calculation means.

【0022】

Further, in the color conversion device according to claim 9, the output value of the color image forming device in an arbitrary three-dimensional input color space is converted into lattice points on the three-dimensional input color space divided into three-dimensional figures. In a color conversion device that executes color conversion by interpolating a set grid point output value, a first storage means for storing grid point information belonging to the color reproduction range of the color image forming device and the color. A second storage means for temporarily storing output values on lattice points outside the color reproduction range and partly within the color reproduction range of the image forming apparatus, and processing information of the lattice points within the color reproduction range of the color image forming apparatus are temporarily stored. A third storage means for storing colors, a fourth storage means for storing color patch data for color selection, and colors outside and near the color reproduction range of the color image forming apparatus are displayed and color selection is performed. The color patch in which the display selection means for the purpose and the colors corresponding to the colors outside and near the color reproduction range of the color image forming apparatus output to the display selection means are stored in the fourth storage means is the color. It is output to an image forming apparatus, a desired color patch is selected, the selection information is stored in the third storage means, the selected desired grid point is calculated, and the grid point is the color image. It is determined whether or not it is included in the color reproduction range of the forming device, and in the first case where the lattice point is within the color reproduction range, the actual input / output relationship in the color image forming device is simulated. In the second case where the grid point is outside the color reproduction range, the output value on the grid point is used as a variable, and the input outside the color reproduction range of the color image forming apparatus and its vicinity is input / output of the color image forming apparatus. Using the data, the output value on the grid point as a variable is varied so that the reproduction error (color difference) of the entire color conversion result is minimized, and the grid point output value is calculated for each, and this is the first. It is provided with a calculation means to be stored in the second storage means, reads out the grid point information stored in the first storage means and the second storage means, and is based on the grid point output value calculated by the calculation means. It performs color conversion.

【0023】

[Action]

The color conversion device (claim 1) of the present invention uses a simulator constructed by measuring the actual input / output color patches for only the lattice points belonging to the color reproduction range of the image forming device, and uses L * a * b * data. Is converted to the ink control amount CMY that forms a color image. For grid points that belong outside the color reproduction range of the image forming device, use a simulator in which the CMY value corresponding to the color that the image forming device cannot output is used to generate L * a * b * data. Converts to the ink control amount CMY that forms a color image. As a result, output colors of substantially the same color can be obtained for inputs outside the color reproduction range of the image forming apparatus. In addition, even when the input color space is subdivided and many grid points are taken, a huge amount of calculation for calculating the output value on the grid points is eliminated, and the processing time is shortened.

【0024】

Further, the color conversion device (claim 2) of the present invention uses a simulator constructed by measuring the actual input / output color patches for only the lattice points belonging to the color reproduction range of the image forming device, and L * a * b. * Convert data to CMY, an ink control amount that forms a color image. For grid points that belong outside the color reproduction range of the image forming device, the input / output data artificially created so that the input outside the color reproduction range of the image forming device corresponds to the output of the image forming device is used, and the entire color is used. The lattice point output value set as a variable parameter is changed so that the reproduction error (color difference) of the conversion result is minimized, and the L * a * b * data is converted into the ink control amount CMY that forms a color image. As a result, output colors of substantially the same color can be obtained for inputs outside the color reproduction range of the image forming apparatus. Further, when the shape of the color reproduction area of the image forming apparatus is distorted, high-precision color conversion is realized even when the number of divisions of the input color space is small.

【0025】

Further, the color conversion device (claim 3) of the present invention is the first as a storage area (fixed area) in which the grid point information (grid point output value) of the grid points included in the color reproduction region of the image forming device does not change. The grid point information (grid point output value) of the grid points outside the color reproduction range of the image forming apparatus is stored in the storage means of the second storage means as a storage area (variable area) that can be reset or selected. It is stored, and the grid point information stored in these first storage means and the second storage means is read out, and the processing of the first invention, that is, the simulation is performed according to the inside and outside of the reproduction range of the grid points. By executing the color conversion process based on the grid point output value, an output color of substantially the same color can be obtained even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, parameters such as the compression direction and the compression rate can be freely changed.

【0026】

Further, the color conversion device (claim 4) of the present invention is the first as a storage area (fixed area) in which the grid point information (grid point output value) of the grid points included in the color reproduction region of the image forming device does not fluctuate. The grid point information (grid point output value) of the grid points outside the color reproduction range of the image forming apparatus is stored in the storage means of the second storage means as a storage area (variable area) that can be reset or selected. It is stored, and the grid point information stored in these first storage means and the second storage means is read out, and the processing of the second invention, that is, the simulation is performed according to the inside and outside of the reproduction range of the grid points. By executing the color conversion process based on the grid point output value, an output color of substantially the same color can be obtained even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, parameters such as the compression direction and the compression rate can be freely changed.

【0027】

Further, the color conversion device (claim 5) of the present invention selects a desired grid point from the grid points in the color reproduction range treated as fixed data by the user. Then, the output values of the grid points outside the color reproduction range and the selected grid points within the color reproduction range can be set each time, and the processing of the first invention, that is, the simulation according to the inside and outside of the reproduction range of the grid points. The value obtained by executing the color conversion process based on the grid point output value obtained is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out without duplication, and the color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of substantially the same color can be obtained even for inputs outside the region. In addition, it is possible to compress not only the vicinity of the outermost outline of the color reproduction range and the outside but also the entire color space, and the degree thereof can be selected by the user.

【0028】

Further, the color conversion device (claim 6) of the present invention selects a desired grid point from the grid points in the color reproduction range treated as fixed data by the user. Then, the output values of the grid points outside the color reproduction range and the selected grid points within the color reproduction range can be set each time, and the processing of the second invention, that is, the simulation according to the inside and outside of the reproduction range of the grid points. The value obtained by executing the color conversion process based on the grid point output value obtained is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out so as not to be duplicated, and the color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of substantially the same color can be obtained even for inputs outside the region. In addition, not only the compression near the outermost outline of the color reproduction area and the outside but also the compression of the entire color space is made possible, and the degree thereof can be selected by the user.

【0029】

Further, the color conversion device (claim 7) of the present invention stores the input color image signal data in the fourth storage means, and the calculation means is the input color in which the data is divided into a plurality of areas. A color map is created by detecting which area of the space it belongs to and counting the number of pixels for each area. In addition, the calculation means compares this color map with the color reproduction range of the image forming apparatus, selects the lattice points required to output the input image among the lattice points outside the color reproduction range, and selects this as the third grid point. It is stored in the storage means of. Further, the calculation means selects a divided space inside the space (in the radiation axis direction) where the input image data is distributed outside the color reproduction range, and stores this in the third storage means. Then, the output value on the grid point stored in the third storage means is based on the processing of the first invention, that is, the grid point output value obtained by simulating according to the inside and outside of the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out without duplication, and the color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of substantially the same color can be obtained even for inputs outside the region. It also enables the optimum compression of the entire color space corresponding to the input color image. Furthermore, since the output value on the unused grid points is not calculated, the overall processing time is shortened.

【0030】

Further, the color conversion device (claim 8) of the present invention stores the input color image signal data in the fourth storage means, and the calculation means is the input color in which the data is divided into a plurality of areas. A color map is created by detecting which area of the space it belongs to and counting the number of pixels for each area. In addition, the calculation means compares this color map with the color reproduction range of the image forming apparatus, selects the lattice points required to output the input image among the lattice points outside the color reproduction range, and selects this as the third grid point. It is stored in the storage means of. Further, the calculation means selects a divided space inside the space (in the radiation axis direction) where the input image data is distributed outside the color reproduction range, and stores this in the third storage means. Then, the output value on the grid point stored in the third storage means is based on the processing of the second invention, that is, the grid point output value obtained by simulating according to the inside and outside of the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out without duplication, and the color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of substantially the same color can be obtained even for inputs outside the region. It also enables the optimum compression of the entire color space corresponding to the input color image. Furthermore, since the output value on the unused grid points is not calculated, the overall processing time is shortened.

【0031】

Further, in the color conversion device (claim 9) of the present invention, the user selects a desired grid point from the grid points in the color reproduction range, and stores this in the third storage means. For the selected grid points, a grid point output value is calculated by the process of claim 2, and the value is stored in the second storage means. In addition, the colors corresponding to the colors outside and near the color reproduction range of the image forming apparatus output to the display selection means are output by the image forming apparatus using the color patch data stored in the fourth storage means. The user selects the patch. Since the Lab value of the selected patch color is fixed, the user's favorite output color of the image forming device corresponding to the input outside and near the color reproduction range of the image forming device is determined. Then, the information stored in the first storage means and the second storage means is read out, and the color conversion is executed based on the grid point output value. As a result, an output color of substantially the same color can be obtained even for an input outside the color reproduction range of the image forming apparatus. In addition, the user can freely set the compression of the input color space while actually checking the color by himself / herself.

【0032】

[Example]

(Example of Color Conversion Processing) Hereinafter, examples of the color conversion apparatus according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing an example in which a three-dimensional figure which is an input color space (XYZ space) is divided into three-dimensional blocks of the same type as a concept of the color conversion process according to the present invention. As shown in Fig. 1, the XYZ space, which is an arbitrary input color space, is divided into three-dimensional figures of the same type (in this embodiment, it is a cube). Furthermore, when finding the value of the output P at each of the input X, Y, Z coordinates, select the cube containing the input X, Y, Z coordinates, and on the eight vertices of the selected cube. The output value at the output P is obtained by linear interpolation based on the output value (a known value obtained by a predetermined method).

【0033】

Here, when converting to color image data for image formation in the above, X, Y, Z correspond to the input X, Y, Z signals of CIE XYZ (CIE 1931 standard colorimetric system). In the case of a three-color printer, the output P corresponds to the Y (yellow), M (magenta), and C (cyan) signals that control the amount of ink.

【0034】

Next, a specific example of the color conversion process will be described in the order of [Example 1] and [Example 2].

【0035】

[Example 1] This Example 1 realizes the first invention, which will be described in detail below. (Configuration of Example 1) First, the hardware configuration for realizing this embodiment will be described. FIG. 2 is a block diagram showing a schematic configuration of the color conversion apparatus according to the first and second embodiments. In the figure, the CPU 201 as a calculation means for collectively executing the control processing of the entire apparatus and the input color space. It is composed of a ROM 202 that stores the output value on the grid point in the above and an interpolation processing unit 203 that interpolates the grid point output value.

【0036】

Further, the interpolation processing unit 203 is used for RAM 204, in which the grid point information stored in ROM 202 is loaded at the time of execution, and for Y, which generates Y, M, and C signals by referring to the grid point information of RAM 204 from the input signal. It is composed of a processing unit 205, a processing unit 206 for M, and a processing unit 207 for C.

【0037】

(Processing operation of Example 1) Next, the color conversion device configured as described above executes the following processing. The grid point information is stored in the ROM 202, and the CPU 201 loads (data transfer) the grid point information into the RAM 204 of the interpolation processing unit 203 at the time of execution. Further, referring to the grid point information on the RAM 204, the processing unit 205 for C, the processing unit 206 for M, and the processing unit 207 for Y execute interpolation operations, respectively. That is, the C processing unit 205, the M processing unit 206, and the Y processing unit 207 output C signals, M signals, and Y signals that control the amount of ink in the printer.

【0038】

FIG. 3 is a flowchart showing the processing up to the grid point calculation (color conversion table) according to the first embodiment. When this process is started, first, the division range of each axis is determined in the input color space of each axis formed by 3 orthogonal axes (XYZ), and 2ⁿDivided into individual regions as shown in Figure 1 (2n + 1)³Create a number of representative grid points (S301). Next, the LAB value is calculated by performing the XYZ / LAB conversion of the representative lattice points using the conversion formula of the uniform color space shown in (1) below (S302).

【0039】

That is, the XYZ / LAB conversion formula used in step S302 is the uniform color space (L).^*a^*b b^*The three-dimensional coordinates that make up the color space) are the coordinates (brightness index) corresponding to the brightness (brightness) and the two-dimensional Cartesian coordinates that simultaneously consider the two attributes of hue and saturation, and are given by the following equation.

【0040】

L^*= 116 (Y / Y₀)^1/3-16 a^*= 500 [(X / X₀)^1/3-(Y / Y₀)^1/3] b b^*= 200 [(Y / Y₀)^1/3-(Z / Z₀)^1/3] (1) 【0041】

Subsequently, after the above processing, it is determined whether or not the representative grid points are included in the color reproduction region of the image forming apparatus, that is, whether or not the grid points are within the color reproduction region (S303). In such a case, L is used for internal / external judgment in the color reproduction range.^*a^*b b^*Quantumize the color space in the direction of brightness, hue, and saturation, and CMY L^*a^*b b^*Using a simulator (described later), create the outermost data of the color gamut (gamut) of the image forming apparatus in each quantization space, and use this.

【0042】

In step S303 above, when it is determined that the representative grid points are within the color reproduction range of the image forming apparatus, a simulator is constructed in which the actual input / output relationship in the image forming apparatus is constructed based on the measured values of the actual input / output color patch. The output color at each grid point is calculated directly by using and simulating (S304). That is, here, L^*a^*b b^*The color space data is converted into an ink control amount CMY that forms a color image.

【0043】

The simulation in the above process is CMY L in this example.^*a^*b b^*And L^*a^*b b^* A neural network trained by a CMY simulator is used. The printer simulator in this embodiment is specifically constructed as follows. That is, actually, multiple sets of four output color patches (single color and mixed color of CMY) of the image forming apparatus are output, and these are measured with a colorimeter to create multiple sets of CMY value-color measurement value pair data. Furthermore, this is learned in the forward direction of CMY input L * a * b * output and in the reverse direction of L * a * b * input CMY output.

【0044】

On the other hand, in step S303, when it is determined that the representative grid points are out of the color reproduction range of the image forming apparatus, the image is imaged using a simulator constructed by virtually defining the CMY value corresponding to the color that the image forming apparatus cannot output. The output at each grid point is calculated directly by simulating the fictitious input / output relationship in the forming device (S305). That is, in step S305, the L of the representative grid points determined to be outside the color reproduction range of the image forming apparatus.^*a^*b b^*Converts the data to the ink control amount CMY that forms the color image.

【0045】

In addition, the simulator used in step S305 uses different learning data for construction from step S304. That is, L in this case^*a^*b b^* The CMY simulator is an artificially created pair of CMY values (L that cannot be actually output by the image forming device).^*a^*b b^*Create multiple sets of CMY corresponding to (L) in the opposite direction (L)^*a^*b b^*I am learning about input CMY output).

【0046】

Next, if the output values of all the grid points are determined in step S304 or step S305, the calculated grid point output values are filed (S306), stored in ROM 202, and this process is terminated. ..

【0047】

(Effect of Example 1) Therefore, by the processing of Example 1 above, it is possible to output as much as possible color even for an input outside the color reproduction range of the image forming apparatus, and the input color space is finely divided and a grid is used. Even if the number of points is increased, it is not necessary to perform a huge amount of calculation to calculate the output value on the grid points, and the processing time can be shortened.

【0048】

[Example 2] This Example 2 realizes the second invention, which will be described in detail below. (Processing operation of Example 2) Next, the color conversion processing according to Example 2 will be described using the color conversion device shown in FIG. FIG. 4 is a flowchart showing the processing up to the grid point calculation (color conversion table) according to the second embodiment. When this process is started, first, the division range of each axis is determined in the input color space of each axis formed by 3 orthogonal axes (XYZ), and 2ⁿDivided into individual regions as shown in Figure 1 (2n + 1)³Create a number of representative grid points (S401). Next, the LAB value is calculated by performing the XYZ / LAB conversion of the representative lattice points using the above-mentioned uniform color space conversion formula (1) (S402).

【0049】

Subsequently, after the above processing, it is determined whether or not the representative grid points are included in the color reproduction region of the image forming apparatus, that is, whether or not the grid points are within the color reproduction region (S403). In such a case, L is used for internal / external judgment in the color reproduction range.^*a^*b b^*Quantumize the color space in the direction of brightness, hue, and saturation, and CMY L^*a^*b b^*Using a simulator (described later), create the outermost data of the color gamut (gamut) of the image forming apparatus in each quantization space, and use this.

【0050】

If it is determined in step S403 above that it is within the color reproduction range of the image forming device, the actual input / output relationship in the image forming device is simulated using a simulator constructed based on the measured values of the actual input / output patch. The output color at each grid point is calculated directly by (S404). That is, here, L^*a^*b b^*The color space data is converted into an ink control amount CMY that forms a color image.

【0051】

The simulation in the above process is CMY L in this example.^*a^*b b^*And L^*a^*b b^* A neural network trained by a CMY simulator is used. The printer simulator in this embodiment is specifically constructed as follows. That is, actually, multiple sets of four output color patches (single color and mixed color of CMY) of the image forming apparatus are output, and these are measured with a colorimeter to create multiple sets of CMY value-color measurement value pair data. Furthermore, this is learned in the forward direction of CMY input L * a * b * output and in the reverse direction of L * a * b * input CMY output.

【0052】

On the other hand, if it is determined in step S403 that it is outside the color reproduction range of the image forming apparatus, the output value of the representative grid point determined to be outside the color reproduction range of the image forming apparatus is set as a variable (S405), and in step S406. Transition.

【0053】

Subsequently, when the processing of step S404 or step S405 is executed, the input / output data artificially created so that the input outside the color reproduction range of the image forming apparatus corresponds to the output of the apparatus is used, and the grid point output as a variable is used. The value is calculated by changing it so that the reproduction error (color difference) of the color conversion result is minimized (S406). Further, when the output values of all the grid points are determined in the above, the calculated grid point output values are filed (S407), stored in ROM202, and this process is terminated.

【0054】

Here, the process in step S406 will be described in more detail. FIG. 5 is a block diagram showing a calculation method of the grid point output value outside the color reproduction range of the image forming apparatus. In the figure, 501 is a color conversion parameter determination unit that converts XYZ data to CMY data based on parameters for color conversion, and 502 is a CMY L * a * b * that converts CMY data to L'a'b'. It is a conversion simulator.

【0055】

In the above configuration, the output values are determined as shown in Fig. 5 for the N XYZ values outside the color reproduction range of the image forming device and near the outermost part of the color reproduction area, and for the grid points within the color reproduction range of the image forming device. The color conversion parameter determination unit 501 is used to convert to CMY, and the CMY L * a * b * conversion simulator 502 is used to convert this to L'a'b'.

【0056】

Therefore, the color difference error between this L'a'b'and the Lab value (artificially made to correspond) within the color reproduction range of the image forming apparatus corresponding to the input is minimized for all N images. In step S403, the output value of the representative lattice point of the color conversion parameter determination unit 501 determined to be outside the color reproduction range of the image forming apparatus is changed and determined.

【0057】

(Effect of Example 2) Therefore, by the processing of Example 2 above, it is possible to output as much as possible color even for an input outside the color reproduction range of the image forming apparatus, and the shape of the color reproduction range of the image forming apparatus. If is distorted, color conversion can be performed with high accuracy even if the number of divisions in the input color space is small. In addition, even if there is a considerable contradiction in the input / output data of the image forming apparatus created intentionally, it does not diverge when calculating the grid point output value.

【0058】

Next, based on the processes described in [Example 1] and [Example 2] above, color conversion devices using different hardware configurations are described in [Example 3], [Example 4], and [Example 2]. 5], [Example 6], and [Example 7] will be described in this order.

【0059】

[Example 3] This Example 3 realizes the third invention, which will be described in detail below. (Structure of Example 3) FIG. 6 is a block diagram showing a schematic configuration of the color conversion device according to the third embodiment. ROM 602 as the first storage means for storing the output value on the grid point in the input color space, the interpolation processing unit 603 for interpolating the grid point output value, and the grid point outside the color reproduction gamut (gamut). It is composed of a ROM group 608 as a second storage means including ROMs 609 to 611 for storing the output value of.

【0060】

Further, the interpolation processing unit 603 refers to the RAM 604 in which the grid point information stored in the ROM 602 and the ROM group 608 is loaded at the time of execution, and the Y, M, C signals by referring to the grid point information of the RAM 604 from the input signal, respectively. It is composed of a processing unit 605 for Y, a processing unit 606 for M, and a processing unit 607 for C to be generated.

【0061】

(Processing Operation of Example 3) The operation of the color conversion device configured as described above will be described. The output values on the grid points within the color gamut of the image forming apparatus in the input color space are stored in ROM 602, and ROM 609, 610, and 611 of ROM group 608, respectively, are on the grid points outside the color gamut. Save the output value. That is, a plurality of output value patterns are prepared in the ROM group 608. At execution time, the CPU 601 selects the grid point output value outside the color reproduction range of any one of the ROM groups 608 together with the information of the ROM 602, and loads (data transfers) it into the RAM 604 of the interpolation processing unit 603. Further, the output value in the output P is linearly interpolated by the interpolation processing unit 603 based on the grid point output value obtained in the above-mentioned Example 1 or Example 2. As a result, the C processing unit 605, the M processing unit 606, and the Y processing unit 607 output C signals, M signals, and Y signals that control the amount of ink in the printer.

【0062】

(Effect of Example 3) Therefore, by the configuration of Example 3 and its processing, it is possible to output substantially the same color even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, the compression conditions such as the compression direction and the compression rate can be freely changed each time.

【0063】

[Example 4] This Example 4 realizes the fourth invention, which will be described in detail below. (Structure of Example 4) FIG. 7 is a block diagram showing a schematic configuration of the color conversion apparatus according to the fourth embodiment. ROM 702 as the first storage means for storing the output value on the grid point in the input color space, the interpolation processing unit 703 for interpolating the grid point output value, and the grid point outside the color reproduction gamut (gamut). It is composed of RAM708 as a second storage means for temporarily storing the output value.

【0064】

Further, the interpolation processing unit 703 generates Y, M, and C signals by referring to the grid point information of RAM 704 from the input signal and RAM 704 in which the grid point information stored in ROM 702 and RAM 708 is loaded at the time of execution. It is composed of a processing unit 705 for Y, a processing unit 706 for M, and a processing unit 707 for C.

【0065】

(Processing Operation of Example 4) The operation of the color conversion device configured as described above will be described. The CPU 701 obtains the grid point output value by the method of [Example 1] or [Example 2] described above, and temporarily stores it in the RAM 708. Then, it is loaded (data transferred) into the RAM 704 of the interpolation processing unit 703, and the output value in the output P is linearly interpolated by the interpolation processing unit 703 based on these grid point output values. As a result, the C processing unit 705, the M processing unit 706, and the Y processing unit 707 output C signals, M signals, and Y signals that control the amount of ink in the printer. Therefore, in this embodiment, the output value on the grid points outside the color reproduction range can be set in RAM708 each time.

【0066】

(Effect of Example 4) Therefore, by the configuration of Example 4 and its processing, it is possible to output as much equivalent color as possible even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, the compression conditions such as the compression direction and the compression rate can be freely changed each time.

【0067】

[Example 5] This Example 5 realizes the fourth and sixth inventions, which will be described in detail below. (Structure of Example 5) FIG. 8 is a block diagram showing a schematic configuration of the color conversion device according to the fifth embodiment. ROM802 as a second storage means that stores the output values on the grid points in the input color space, the interpolation processing unit 803 that interpolates the grid point output values, and color reproduction outside the color reproduction range (gamut) and some colors. RAM808 as a second storage means for temporarily storing the output values on the grid points in the region, and the processing information of the grid points in the color reproduction region of the image forming apparatus are temporarily stored. It is composed of RAM809 as a third storage means for this purpose and a selection unit 810 as a selection means for selecting a method of processing grid points for grid points belonging to the color reproduction range.

【0068】

Further, the interpolation processing unit 803 refers to the RAM 804 in which the grid point information stored in the ROM 802, RAM 808, and RAM 809 is loaded at the time of execution, and the Y, M, C signals by referring to the grid point information of the RAM 804 from the input signal. It is composed of Y processing unit 805, M processing unit 806, and C processing unit 807, respectively.

【0069】

(Processing Operation of Example 5) The operation of the color conversion device configured as described above will be described. First, the user selects a desired grid point (basically, a grid point near the outermost outline of the color reproduction region) from the grid points in the color reproduction region treated as fixed data in the fourth embodiment. This selected grid point information is temporarily stored in RAM809. Further, this grid point information is also treated as a grid point outside the color reproduction range in Example 4. That is, the output values of the grid points outside the color reproduction range and the selected grid points within the color reproduction range can be set each time, and the grid points are set by the CPU 801 based on the processing of the above-mentioned Example 1 or Example 2. Calculate the output value and temporarily store the result in RAM808.

【0070】

Next, when the CPU 801 executes the color correction process, it refers to the grid point information stored in the RAM 809 and loads it into the RAM 804 so that the grid point output value data in the color reproduction range does not overlap. That is, the grid points outside the color reproduction range of the image forming apparatus and the grid points selected within the color reproduction range are set each time in the same manner as the grid points outside the color reproduction range in Example 4, and are further carried out by the CPU 801. It is calculated by the processing of Example 1 and Example 2, and the result is temporarily stored in RAM808. After that, this stored information is loaded into RAM804 together with the information of ROM802, and the output value at the output P is linearly interpolated by the interpolation processing unit 803 based on the grid point output value.

【0071】

(Effect of Example 5) Therefore, by the configuration of Example 5 and its processing, it is possible to output as much equivalent color as possible even for an input outside the color reproduction range of the image forming apparatus. Furthermore, not only the compression near the outermost part of the color reproduction area and the outside but also the entire color space can be compressed. In addition, the degree can be determined by the user.

【0072】

[Example 6] This Example 6 realizes the seventh and eighth inventions, which will be described in detail below. (Structure of Example 6) FIG. 9 is a block diagram showing a schematic configuration of the color conversion device according to the sixth embodiment. ROM 902 as the first storage means for storing the output value on the grid point in the input color space, the interpolation processing unit 903 for interpolating the grid point output value, and color reproduction outside the color reproduction range (gamut) and part of the color reproduction. RAM908 as a second storage means for temporarily storing the output values on the grid points in the region, and the processing information of the grid points in and outside the color reproduction region of the image forming apparatus are temporarily stored. It is composed of RAM909 as a third storage means for storing and RAM910 as a fourth storage means for temporarily storing the input color image data.

【0073】

Further, the interpolation processing unit 903 refers to the RAM 904 in which the grid point information stored in the ROM 902, RAM 908, RAM 909, and RAM 910 is loaded at the time of execution, and the grid point information of the RAM 904 from the input signal, and Y, M, C. It is composed of a Y processing unit 905, an M processing unit 906, and a C processing unit 907 that generate signals, respectively.

【0074】

(Processing Operation of Example 6) The operation of the color conversion device configured as described above will be described. First, the input color image data is written to the RAM 910. The CPU 901 determines which area of the input color space divided into a plurality of areas the color image data stored in the RAM 910 belongs to, and further counts the number of pixels for each area. This creates a color map.

【0075】

Furthermore, the CPU901 compares the created color map with the color reproduction area of the image forming apparatus, selects the necessary lattice points for outputting the input image among the lattice points outside the color reproduction area, and converts this into the RAM909. Remember. Further, since the CPU901 uses a uniform color space such as L * a * b * as the input space in this embodiment, it is a divided space inside the space (radial axis direction) in which the input image data is distributed outside the color reproduction range. The grid points of, that is, the grid points in the color reproduction range treated as fixed data in Example 4 are selected.

【0076】

After that, the above-selected grid point information is also temporarily stored in RAM909. The output values on the grid points (some grid points inside and outside the color reproduction range) stored in the RAM 909 are calculated by the CPU 901 in the processes of Examples 1 and 2, and are stored in the RAM 908.

【0077】

Next, when the CPU 901 executes the color correction process, it refers to the grid point information stored in the RAM 909 and loads it into the RAM 904 so that the grid point output value data in the color reproduction range does not overlap. That is, only the grid points outside the color reproduction range of the image forming apparatus and the grid points selected within the color reproduction range are calculated by the CPU901 in the processes of Examples 1 and 2, and the results are temporarily stored in RAM908. Will be done. After that, it is loaded into RAM904 together with the information of ROM902, and the output value at output P is obtained by linear interpolation by the interpolation processing unit 903 based on the grid point output value.

【0078】

(Effect of Example 6) Therefore, by the configuration of Example 6 and its processing, it is possible to output as much as possible color to the input outside the color reproduction range of the image forming apparatus, and the input color image can be obtained. It is possible to perform compression of the entire corresponding optimum color space. Moreover, since the output value on the unused grid points is not calculated, the processing time can be shortened.

【0079】

[Example 7] This Example 7 realizes the ninth invention, which will be described in detail below. (Structure of Example 7) FIG. 10 is a block diagram showing a schematic configuration of the color conversion device according to the seventh embodiment. ROM 1002 as the first storage means for storing the output values on the grid points in the input color space, the interpolation processing unit 1003 for interpolating the grid point output values, and color reproduction outside the color reproduction gamut (gamut) and part of the colors. RAM1008 as a second storage means for temporarily storing the output value on the grid points in the region, and processing information of the grid points in the color reproduction region of the image forming apparatus are temporarily stored. RAM1009 as a third storage means for color selection, ROM1010 as a fourth storage means for storing patch creation data used for color selection, and CRT (or control panel) as a display selection means used for color selection. ) Consists of 1011. The 1012 is an image forming apparatus.

【0080】

Further, the interpolation processing unit 1003 refers to RAM1004 in which the grid point information stored in ROM1002, RAM1008, RAM1009, and RAM1010 is loaded at the time of execution, and Y, M, C by referring to the grid point information of RAM1004 from the input signal. It is composed of a Y processing unit 1005, an M processing unit 1006, and a C processing unit 1007, which generate signals, respectively.

【0081】

(Processing Operation of Example 7) The operation of the color conversion device configured as described above will be described. This operation is basically the same as that of the fifth embodiment described above. First, the user selects a desired grid point (basically, a grid point near the outermost outline of the color reproduction region) from the grid points in the color reproduction region. This selected information is stored in RAM1009. Furthermore, the selected grid points are calculated by the CPU 1001 as shown below and stored in the RAM 1008.

【0082】

That is, as the grid points in the above, as described in Example 2, input / output data intentionally created so that the input outside and near the color reproduction range of the image forming apparatus corresponds to the output of the image forming apparatus is used. It is calculated by changing the grid point output value set as a variable so that the reproduction error (color difference) of the entire color conversion result is minimized.

【0083】

In addition, when calculating the grid points, it is necessary to create Lab values (artificially corresponded) within the color reproduction range of the image forming apparatus corresponding to the input in FIG. In this embodiment, the color output to the CRT (or control panel) 1011 (outside the color reproduction range of the image forming apparatus and its vicinity) in order to create paired data of the Lab value (Fig. 5) within the input-color reproduction range. The color corresponding to (color) is selected by the user from the patches (created with the data of ROM 1010) output by the image forming apparatus 1012.

【0084】

As described above, since the Lab value of the selected patch color is fixed, the output color of the image forming device, which is the user's preference, is determined in response to the input outside the color reproduction range of the image forming device and its vicinity. To. After that, as shown in Fig. 5, the output value of the representative grid points is changed and determined so that the total color difference error is minimized for all N pieces. The sample color (color output to CRT1011) is arbitrarily selected by CPU1001 according to the information of RAM1009 as needed.

【0085】

The output value calculated by the above processing is temporarily stored in RAM1008. This stored output value is loaded into RAM1004 together with the information of ROM1002. Then, the interpolation processing unit 1003 obtains the output value at the output P by linear interpolation based on this load information, that is, the grid point output value.

【0086】

(Effect of Example 7) Therefore, by the configuration of Example 7 and its processing, it is possible to output the same color as possible even for an input outside the color reproduction range of the image forming apparatus, and the user can output the same color by himself / herself. You can freely decide the compression of the input color space while actually checking the desired color.

【0087】

[Effect of the invention]

As described above, according to the color conversion device (claim 1) according to the present invention, a simulator constructed with actual measurement values of input / output color patches is provided only for lattice points belonging to the color reproduction range of the image forming device. Using, L * a * b * data is converted into the ink control amount CMY that forms a color image. For grid points that belong outside the color reproduction range of the image forming device, use a simulator in which the CMY value corresponding to the color that the image forming device cannot output is used to generate L * a * b * data. Converts to the ink control amount CMY that forms a color image. Therefore, it is possible to obtain an output color of substantially the same color for an input outside the color reproduction range of the image forming apparatus. Further, even when the input color space is subdivided and a large number of grid points are taken, a huge amount of calculation for calculating the output value on the grid points can be eliminated, and the processing time can be shortened.

【0088】

Further, according to the color conversion device (claim 2) according to the present invention, only the lattice points belonging to the color reproduction range of the image forming device are L * using a simulator constructed with the measured values of the actual input / output color patches. Converts a * b * data to the ink control amount CMY that forms a color image. For grid points that belong outside the color reproduction range of the image forming device, the input / output data artificially created so that the input outside the color reproduction range of the image forming device corresponds to the output of the image forming device is used, and the entire color is used. The lattice point output value set as a variable parameter is changed so that the reproduction error (color difference) of the conversion result is minimized, and the L * a * b * data is converted into the ink control amount CMY that forms a color image. Therefore, it is possible to obtain an output color of substantially the same color for an input outside the color reproduction range of the image forming apparatus. Further, when the shape of the color reproduction region of the image forming apparatus is distorted, high-precision color conversion can be realized even when the number of divisions of the input color space is small.

【0089】

Further, according to the color conversion device (claim 3) according to the present invention, the grid point information (grid point output value) of the grid points included in the color reproduction region of the image forming apparatus is set as a storage area (fixed area) that does not fluctuate. The grid point information (grid point output value) of the grid points outside the color reproduction range of the image forming apparatus is stored in the first storage means of the second storage area (fluctuation area) that can be reset or selected. It is stored in a storage means, and the grid point information stored in these first storage means and the second storage means is read out, and the processing of the first invention, that is, simulation according to the inside and outside of the reproduction range of the grid points. Since the color conversion process is executed based on the grid point output value obtained in the above procedure, it is possible to obtain an output color of substantially the same color even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, parameters such as the compression direction and the compression rate can be freely changed.

【0090】

Further, according to the color conversion device (claim 4) according to the present invention, the grid point information (grid point output value) of the grid points included in the color reproduction region of the image forming apparatus is set as a storage area (fixed area) that does not fluctuate. The grid point information (grid point output value) of the grid points outside the color reproduction range of the image forming apparatus is stored in the first storage means of the second storage area (fluctuation area) that can be reset or selected. It is stored in a storage means, and the grid point information stored in these first storage means and the second storage means is read out, and the processing of the second invention, that is, simulation according to the inside and outside of the reproduction range of the grid points. Since the color conversion process is executed based on the grid point output value obtained in the above procedure, it is possible to obtain an output color of substantially the same color even for an input outside the color reproduction range of the image forming apparatus. Further, when the input color space is compressed into the color reproduction space of the image forming apparatus, parameters such as the compression direction and the compression rate can be freely changed.

【0091】

Further, according to the color conversion device (claim 5) according to the present invention, the user selects a desired grid point from the grid points in the color reproduction range treated as fixed data. Then, the output values of the grid points outside the color reproduction range and the selected grid points within the color reproduction range can be set each time, and the processing of the first invention, that is, the simulation according to the inside and outside of the reproduction range of the grid points. The value obtained by executing the color conversion process based on the grid point output value obtained is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out so as not to be duplicated, and the color conversion processing is executed. It is possible to obtain an output color of substantially the same color for the input of. Moreover, not only the compression near the outermost part of the color reproduction area and the outside but also the compression of the entire color space is realized, and the degree can be selected by the user.

【0092】

Further, according to the color conversion device (claim 6) according to the present invention, the user selects a desired grid point from the grid points in the color reproduction range treated as fixed data. Then, the output values of the grid points outside the color reproduction range and the selected grid points within the color reproduction range can be set each time, and the processing of the second invention, that is, the simulation according to the inside and outside of the reproduction range of the grid points. The value obtained by executing the color conversion process based on the grid point output value obtained is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out so as not to be duplicated, and the color conversion processing is executed, so that the color conversion processing is performed outside the color reproduction region of the image forming apparatus. It is possible to obtain an output color of substantially the same color for the input of. Moreover, not only the compression near the outermost part of the color reproduction area and the outside but also the compression of the entire color space can be realized, and the degree can be selected by the user.

【0093】

Further, according to the color conversion device (claim 7) according to the present invention, the input color image signal data is stored in the fourth storage means, and the calculation means divides the data into a plurality of areas. It detects which region of the input color space it belongs to, counts the number of pixels in each region, and creates a color map. In addition, the calculation means compares this color map with the color reproduction range of the image forming apparatus, selects the lattice points required to output the input image among the lattice points outside the color reproduction range, and selects this as the third grid point. It is stored in the storage means of. Further, the calculation means selects a divided space inside the space (in the radiation axis direction) where the input image data is distributed outside the color reproduction range, and stores this in the third storage means. Then, the output value on the grid point stored in the third storage means is based on the processing of the first invention, that is, the grid point output value obtained by simulating according to the inside and outside of the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out so as not to be duplicated, and the color conversion processing is executed, so that the color conversion processing is performed outside the color reproduction region of the image forming apparatus. It is possible to obtain an output color of substantially the same color for the input of. In addition, it is possible to realize the optimum compression of the entire color space corresponding to the input color image. Furthermore, since the output value on the unused grid points is not calculated, the overall processing time can be shortened.

【0094】

Further, according to the color conversion device (claim 8) according to the present invention, the input color image signal data is stored in the fourth storage means, and the calculation means divides the data into a plurality of areas. It detects which region of the input color space it belongs to, counts the number of pixels in each region, and creates a color map. In addition, the calculation means compares this color map with the color reproduction range of the image forming apparatus, selects the lattice points required to output the input image among the lattice points outside the color reproduction range, and selects this as the third grid point. It is stored in the storage means of. Further, the calculation means selects a divided space inside the space (in the radiation axis direction) where the input image data is distributed outside the color reproduction range, and stores this in the third storage means. Then, the output value on the grid point stored in the third storage means is based on the processing of the second invention, that is, the grid point output value obtained by simulating according to the inside and outside of the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction region is read out so as not to be duplicated, and the color conversion processing is executed, so that the color conversion processing is performed outside the color reproduction region of the image forming apparatus. It is possible to obtain an output color of substantially the same color for the input of. In addition, it is possible to realize the optimum compression of the entire color space corresponding to the input color image. Furthermore, since the output value on the unused grid points is not calculated, the overall processing time can be shortened.

【0095】

Further, according to the color conversion device (claim 9) according to the present invention, the user selects a desired grid point from the grid points in the color reproduction range, and stores this in the third storage means. For the selected grid points, a grid point output value is calculated by the process of claim 2, and the value is stored in the second storage means. In addition, the colors corresponding to the colors outside and near the color reproduction range of the image forming apparatus output to the display selection means are output by the image forming apparatus using the color patch data stored in the fourth storage means. The user selects the patch. Since the Lab value of the selected patch color is fixed, the user's favorite output color of the image forming apparatus corresponding to the input outside and near the color reproduction range of the image forming apparatus is determined. Then, the information stored in the first storage means and the second storage means is read out, and the color conversion is executed based on the grid point output value. Therefore, it is possible to obtain an output color of substantially the same color even for an input outside the color reproduction range of the image forming apparatus. In addition, the user can freely set the compression of the input color space while actually checking the color by himself / herself.

[Simple explanation of drawings]

[Figure 1]

It is explanatory drawing which shows the example which divided the 3D figure which is an input color space (XYZ space) into 3D blocks of the same type as the concept of the color conversion processing which concerns on this invention.

[Figure 2]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 1 and Example 2.

[Fig. 3]

It is a flowchart which shows the process up to the grid point calculation (color conversion table) which concerns on Example 1. FIG.

[Fig. 4]

It is a flowchart which shows the process up to the grid point calculation (color conversion table) which concerns on Example 2.

[Fig. 5]

It is a block diagram which shows the calculation method of the grid point output value outside the color reproduction region of the image forming apparatus which concerns on this Example.

[Fig. 6]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 3. FIG.

[Fig. 7]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 4. FIG.

[Fig. 8]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 5.

[Fig. 9]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 6.

[Fig. 10]

It is a block diagram which shows the schematic structure of the color conversion apparatus which concerns on Example 7.

[Explanation of symbols]

201,601,701,801,901,1001 CPU 608 ROM group 708,808,809,908,909,910,1008 RAM 810 selection 1010 ROM 1011 CRT 1012 Image forming device