JPH08228296A - Color conversion device - Google Patents

Abstract

(57) [Abstract] [Purpose] When the output of the same color is possible as much as possible even when the input is out of the color reproduction range of the image forming apparatus, and the input color space is subdivided to obtain a large number of grid points. However, the output value on the grid point is calculated efficiently. [Structure] In the first case where a grid point on the three-dimensional input color space is within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and the grid point is outside the color reproduction range. In the second case, a CPU 201 for simulating inputs outside the color reproduction area of the color image forming apparatus and in the vicinity thereof so as to correspond to input / output relationships of the color image forming apparatus, and calculating grid point output values, respectively. To do.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color conversion device for inputting a color image signal, converting it into color image data for image formation, and outputting it. ) A color conversion device for outputting an external input color image in substantially the same color.

[0002]

2. Description of the Related Art Conventionally, there has been known a color conversion device using a memory map as a color conversion device for performing color correction of a color image signal. As a reference technical document related to a color conversion device using this memory map, for example, first, Japanese Patent Publication No.
"Signal interpolation method in memory device" disclosed in JP-A-8-16180, and "Interpolation method and color correction method" disclosed in JP-A-5-75848.
Thirdly, there is a "color conversion device" disclosed in Japanese Patent Laid-Open No. 5-284346.

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

In the second method, XYZ
The space is divided into a plurality of triangular prisms, and one triangular prism including a given X, Y, Z coordinate is selected from the plurality of triangular prisms,
The output value set in the selected triangular prism is interpolated.

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

[0006]

However, in the conventional color conversion apparatus and the method therefor as described above, when the input color space is compressed into the color reproduction range of the image forming apparatus, the image forming apparatus is used. When the input is out of the color reproduction range, the color output from the image forming apparatus is far from the input color, that is, there is a problem in the color reproducibility in the input outside the color reproduction range.

In addition to the above, there are the following problems. That is, firstly, 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 huge. Secondly, the color gamut shape of the image forming apparatus is increased. If the input color space is distorted, high-accuracy color conversion cannot be performed if the number of divisions of the input color space is reduced. Can not be changed, 4th
In the vicinity of the outermost color gamut and outside, it is not possible to compress the entire color space. Fifth, the optimum color space corresponding to the input color image is not compressed and the output value on the grid point that is not used. Takes a long time to calculate
In addition, there was a problem that the user could not set accurately while monitoring the actual output color.

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

Further, according to the present invention, it is possible to output the same color as much as possible even when the input is out of the color reproduction range of the image forming apparatus, and when the shape of the color reproduction area of the image forming apparatus is distorted, the input is performed. A second object is to realize highly accurate color conversion even when the number of color space divisions is small.

Further, according to the present invention, it is possible to output the same color as much as possible even for an input outside the color reproduction range of the image forming apparatus, and to compress the input color space into the color reproduction space of the image forming apparatus. A third object is to make it possible to change the compression parameters such as the compression direction and the compression rate as needed.

Further, according to the present invention, it is possible to output the same color as much as possible even if the input is out of the color reproduction range of the image forming apparatus. The fourth is to be able to set the overall compression ratio, etc.
The purpose of.

Further, according to the present invention, it is possible to output the same color as much as possible even when the input is out of the color reproduction range of the image forming apparatus, and to compress the entire optimum color space corresponding to the input color image. A fifth object is to efficiently enable the above.

Further, according to the present invention, it is possible to output the same color as much as possible even when the input is out of the color reproduction range of the image forming apparatus, and the user can compress the input color space to check the actual output color. The sixth purpose is to enable accurate setting.

[0014]

In order to achieve the above object, in a color conversion apparatus according to claim 1, the output value of a color image forming apparatus in an arbitrary three-dimensional input color space is converted into a three-dimensional figure. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points in the three-dimensional input color space divided into two, color reproduction in which the grid points are different in color image formation In the first case where the grid point is within the color reproduction area, it is simulated whether the grid point is included in the color gamut. In the second case, which is outside the color reproduction range, simulation is performed so that inputs outside the color reproduction range of the color image forming apparatus and in the vicinity thereof are made to correspond to the input / output relationship of the color image forming apparatus,
It is provided with calculating means for calculating the respective grid point output values.

Further, in the color conversion apparatus according to the second aspect, the output value of the color image forming apparatus in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that performs color conversion by interpolating grid point output values set at grid points, it is determined whether the grid points are included in the color reproduction range of the color image forming apparatus, and the grid is output. In the first case where the point is within the color gamut, the actual input / output relationship in the color image forming apparatus is simulated, and in the second case where the grid point is outside the color gamut, the grid is used. The output value on the point is used as a variable, and the input outside the color reproduction area of the color image forming apparatus and its vicinity is used by using the input / output data of the color image forming apparatus, and the reproduction error (color difference) of the entire color conversion result is minimized. So that By varying the output value on the lattice points was, those having a calculating means for calculating the lattice point output value respectively.

Further, in the color conversion device according to the third aspect, the output value of the color image forming device in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that performs color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. Second storage means for storing a plurality of patterns of output values on grid points outside the color reproduction range of the color image forming apparatus; and grid points on the three-dimensional input color space of the color image forming apparatus. It is determined whether or not it is included in the color reproduction area, and when the grid point is in the color reproduction area, the first input / output relationship in the color image forming apparatus is simulated to obtain the grid point. Outside the color gamut In the second case, a calculation for simulating the input outside the color reproduction area of the color image forming apparatus and its vicinity so as to correspond to the input / output relationship of the color image forming apparatus, and calculating the grid point output values respectively Means for reading any one of the patterns stored in the second storage means and the grid point information stored in the first storage means, and using the grid point output value calculated by the calculation means as the grid point output value. Based on this, color conversion is executed.

Further, in the color conversion apparatus according to the fourth aspect, the output value of the color image forming apparatus in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. Second storage means for storing a plurality of patterns of output values on grid points outside the color reproduction area of the color image forming apparatus; and grid points on the three-dimensional input color space of the color image forming apparatus. It is determined whether or not it is included in the color reproduction area, and when the grid point is in the color reproduction area, a simulation of the actual input / output relationship in the color image forming apparatus is performed. Outside the color gamut In the second case, the output value on the grid point is used as a variable, and the input / output data of the color image forming apparatus is used as the input outside the color reproduction area of the color image forming apparatus and in the vicinity thereof. Reproduction error (color difference)
Such that the output value on the grid point that is a variable is calculated so as to minimize each of the grid point output values, and the grid point output value is calculated. The pattern and the grid point information stored in the first storage means are read out, and the color conversion is executed based on the grid point output value calculated by the calculation means.

Further, in the color conversion device according to the fifth aspect, the output value of the color image forming device in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. A second storage means for temporarily storing output values on grid points outside the color reproduction area of the color image forming apparatus and within a part of the color reproduction area; and a desired one of the selected grid points within the color reproduction area. Selection means for selecting a grid point and a processing method for the grid point, third storage means for storing the processing information selected by the selection means, and grid point information selected by the selection means The third note It is read from the means and it is judged whether or not it is included in the color reproduction area of the color image forming apparatus. In the first case where the grid points are within the color reproduction area, the actual input / output of the color image forming apparatus In a second case in which the relationship is simulated and the grid points are outside the color reproduction area, the input outside the color reproduction area of the color image forming apparatus and in the vicinity thereof corresponds to the input / output relationship of the color image forming apparatus. And calculating means for respectively calculating grid point output values and storing them in the second storage means, and storing the grid point output values in the first storage means and the second storage means. The grid point information that exists,
The color conversion is executed based on the grid point output values calculated by the calculating means.

Further, in the color conversion apparatus according to the sixth aspect, the output value of the color image forming apparatus in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. A second storage means for temporarily storing output values on grid points outside the color reproduction area of the color image forming apparatus and within a part of the color reproduction area; and a desired one of the selected grid points within the color reproduction area. Selection means for selecting a grid point and a processing method for the grid point, third storage means for storing the processing information selected by the selection means, and grid point information selected by the selection means The third note It is read from the means and it is determined whether or not it is included in the color reproduction area of the color image forming apparatus. In the first case where the grid points are within the color reproduction area, the actual input / output of the color image forming apparatus is performed. In a second case where the 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 input outside the color reproduction range of the color image forming apparatus and in the vicinity thereof is referred to as the above. Using the input / output data of the color image forming apparatus, the output values on the grid points, which are variables, are varied so that the reproduction error (color difference) of the overall color conversion result is minimized, and the grid point output values are changed. Calculation means for calculating, reading out the grid point information stored in the first storage means and the second storage means, and executing color conversion based on the grid point output value calculated by the calculation means. What to do A.

Further, in the color conversion device according to the seventh aspect, the output value of the color image forming device in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. Second storage means for temporarily storing output values on grid points outside the color reproduction area and part of the color reproduction area of the color image forming apparatus, and processing of grid points within the color reproduction area of the color image forming apparatus Third storage means for temporarily storing information, fourth storage means for temporarily storing information of the input color image signal,
From the image data stored in the fourth storage means, it is detected which region of the input color space divided into a plurality of regions belongs to, the number of pixels is counted for each region to create a color map, The color map is compared with the color gamut of the color image forming apparatus, and a grid point necessary for outputting the input image is selected from grid points outside the color gamut, and the grid point is stored in the third storage. And storing the color image in the color reproduction area of the color image forming apparatus, and in the first case where the grid point is within the color reproduction area, the color image formation is performed. In a second case where the actual input / output relationship in the apparatus is simulated and the grid point is outside the color reproduction area, the input outside the color reproduction area of the color image formation apparatus and in the vicinity thereof is input to the color image formation apparatus Corresponding to the input / output relation of And simulation so that,
And calculating means for respectively calculating grid point output values and storing the grid value output values in the second storage means, reading grid point information stored in the first storage means and the second storage means, Color conversion is executed based on the grid point output values calculated by the calculating means.

Further, in the color conversion apparatus according to the eighth aspect, the output value of the color image forming apparatus in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. Second storage means for temporarily storing output values on grid points outside the color reproduction area and part of the color reproduction area of the color image forming apparatus, and processing of grid points within the color reproduction area of the color image forming apparatus Third storage means for temporarily storing information, fourth storage means for temporarily storing information of the input color image signal,
From the image data stored in the fourth storage means, it is detected which region of the input color space divided into a plurality of regions belongs to, the number of pixels is counted for each region to create a color map, The color map is compared with the color gamut of the color image forming apparatus, and a grid point necessary for outputting the input image is selected from grid points outside the color gamut, and the grid point is stored in the third storage. And storing the color image in the color reproduction area of the color image forming apparatus, and in the first case where the grid point is within the color reproduction area, the color image formation is performed. Simulating the relationship of actual input and output in the device, in the second case where the grid point is outside the color reproduction range, the output value of the grid point is used as a variable,
Input and output outside the color reproduction range of the color image forming apparatus and in the vicinity thereof are performed using input and 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 the grid points in the second storage means so that the reproduction error (color difference) of the entire color conversion result is minimized. And the grid point information stored in the second storage means is read out, and the color conversion is executed based on the grid point output value calculated by the calculation means.

Further, in the color conversion apparatus according to the ninth aspect, the output value of the color image forming apparatus in an arbitrary three-dimensional input color space is divided into three-dimensional figures on the three-dimensional input color space. In a color conversion device that executes color conversion by interpolating grid point output values set at grid points, first storage means for storing grid point information belonging to the color reproduction area of the color image forming apparatus. Second storage means for temporarily storing output values on grid points outside the color reproduction area and part of the color reproduction area of the color image forming apparatus, and processing of grid points within the color reproduction area of the color image forming apparatus Third storage means for temporarily storing information, fourth storage means for storing color patch data for color selection, and color for displaying colors outside and near the color reproduction range of the color image forming apparatus. To make a choice And a color patch which is stored in the fourth storage means and which corresponds to colors outside and near the color reproduction range of the color image forming apparatus outputted to the display selection means. The desired color patch is output to the device, the desired color patch is selected, the selection information is stored in the third storage unit, the desired grid point selected is calculated, and the grid point is the color image forming apparatus. Is included in the color reproduction area, and when the grid point is in the color reproduction area in the first case, the actual input / output relationship in the color image forming apparatus is simulated, In the second case where the point is outside the color reproduction range,
The output values on the grid points are used as variables, and the input and output of the color image forming apparatus outside the color reproduction area and in the vicinity thereof are used, and the reproduction error (color difference) of the entire color conversion result is The output value on the grid point, which is a variable, is calculated so as to be the minimum, and each grid point output value is calculated, and the calculation means is stored in the second storage means. The storage unit and the second storage unit read the grid point information, and execute the color conversion based on the grid point output value calculated by the calculation unit.

[0023]

According to the color conversion apparatus of the present invention (claim 1), L * a * is used by using a simulator constructed by actual measured values of input / output color patches only for grid points belonging to the color reproduction range of the image forming apparatus. The b * data is converted into an ink control amount CMY that forms a color image. For grid points outside the color gamut of the image forming apparatus, L * a * b * data is obtained using a simulator in which CMY values corresponding to colors that the image forming apparatus cannot output grid point output values are virtually set. The ink control amount CMY for forming a color image is converted. As a result, an output color that is substantially the same as the input color outside the color reproduction range of the image forming apparatus can be obtained. Further, even when the input color space is subdivided and the number of grid points is increased, a huge amount of calculation for calculating the output value on the grid points is eliminated and the processing time is shortened.

A color conversion device of the present invention (claim 2)
Uses L * a * b * data as an ink control amount CMY for forming a color image, using a simulator constructed with actual measured values of input and output color patches only for grid points belonging to the color reproduction range of the image forming apparatus. Convert. For grid points outside the color gamut of the image forming apparatus, input / output data that is artificially created so that the input outside the color gamut of the image forming apparatus corresponds to the output of the image forming apparatus is used. The L * a * b * data is converted into an ink control amount CMY that forms a color image by varying the grid point output value set as a variable parameter so that the reproduction error (color difference) of the conversion result is minimized. As a result, an output color that is substantially the same as the input color outside the color reproduction range of the image forming apparatus can be obtained. Further, when the shape of the color gamut of the image forming apparatus is distorted, highly accurate color conversion is realized even if the number of divisions of the input color space is small.

A color conversion device of the present invention (claim 3)
Stores the grid point information (grid point output value) of grid points included in the color reproduction area of the image forming apparatus in the first storage means as a storage area (fixed area) that does not change, and reproduces the color of the image forming apparatus. The grid point information (grid point output value) of grid points outside the area is stored in the second storage means as a storage area (fluctuation area) that can be reset or selected, and the first storage means and the first storage means are stored. The grid point information stored in the second storage unit is read out, and the color conversion processing is executed based on the grid point output values obtained by the simulation according to the processing of the first invention, that is, the inside or outside of the reproduction area of the grid points. By doing so, output colors of substantially the same color can be obtained even for inputs 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.

A color conversion device of the present invention (claim 4)
Stores the grid point information (grid point output value) of grid points included in the color reproduction area of the image forming apparatus in the first storage means as a storage area (fixed area) that does not change, and reproduces the color of the image forming apparatus. The grid point information (grid point output value) of grid points outside the area is stored in the second storage means as a storage area (fluctuation area) that can be reset or selected, and the first storage means and the first storage means are stored. The grid point information stored in the second storage means is read out, and the color conversion processing is executed based on the processing of the second invention described above, that is, based on the grid point output values obtained by simulation according to the inside and outside of the reproduction range of the grid points. By doing so, output colors of substantially the same color can be obtained even for inputs 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.

Further, the color conversion device of the present invention (claim 5)
The user selects a desired grid point from the grid points in the color reproduction area that were treated as fixed data. And
The output values of the grid points outside the color gamut and the selected grid points within the color gamut can be set each time, and the processing according to the first aspect of the invention is performed, that is, the simulation is performed according to whether the grid points are inside or outside the gamut. The value obtained by executing the color conversion process based on the grid point output value is stored in the second storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read so as not to overlap, and color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of approximately the same color can be obtained for inputs outside the range. Further, not only the compression of the outermost part of the color reproduction area and the outside, but also the compression of the entire color space is possible, and the degree can be selected by the user.

A color conversion device of the present invention (claim 6)
The user selects a desired grid point from the grid points in the color reproduction area that were treated as fixed data. And
Output values of grid points outside the color gamut and selected grid points within the color gamut can be set each time, and the processing of the second invention is performed, that is, the simulation is performed according to whether the grid points are inside or outside the gamut. The value obtained by executing the color conversion process based on the grid point output value is stored in the second storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read so as not to overlap, and color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of approximately the same color can be obtained for inputs outside the range. Further, not only the compression of the outermost part of the color reproduction area and the outside, but also the compression of the entire color space is possible, and the degree can be selected by the user.

A color conversion device of the present invention (claim 7)
Stores the input color image signal data in the fourth storage means, and the calculation means detects which area of the input color space divided into a plurality of areas, A color map is created by counting the number of pixels for each. Further, the calculation means compares the color map with the color reproduction area of the image forming apparatus, selects a grid point necessary for outputting the input image among grid points outside the color reproduction area, and selects the grid point from the third color map. It is stored in the storage means. Further, the calculation means selects a divided space inside the space where the input image data is distributed outside the color reproduction area (radial axis direction), 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 grid point output value obtained by the process of the first invention, that is, the simulation inside or outside the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read so as not to overlap, and color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of approximately the same color can be obtained for inputs outside the range. In addition, it is possible to compress the entire optimum color space corresponding to the input color image. Furthermore, since the output values on the unused grid points are not calculated, the overall processing time is shortened.

A color conversion device according to the present invention (claim 8)
Stores the input color image signal data in the fourth storage means, and the calculation means detects which area of the input color space divided into a plurality of areas, A color map is created by counting the number of pixels for each. Further, the calculation means compares the color map with the color reproduction area of the image forming apparatus, selects a grid point necessary for outputting the input image among grid points outside the color reproduction area, and selects the grid point from the third color map. It is stored in the storage means. Further, the calculation means selects a divided space inside the space where the input image data is distributed outside the color reproduction area (radial axis direction), 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 grid point output value obtained by the process of the second invention, that is, the simulation based on the inside or 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, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read so as not to overlap, and color conversion processing is executed to reproduce the color of the image forming apparatus. Output colors of approximately the same color can be obtained for inputs outside the range. In addition, it is possible to compress the entire optimum color space corresponding to the input color image. Furthermore, since the output values on the unused grid points are not calculated, the overall processing time is shortened.

A color conversion device of the present invention (claim 9)
The user selects a desired grid point from the grid points in the color reproduction area and stores it in the third storage means. The grid point output value of the selected grid point is calculated by the process of claim 2, and the value is stored in the second storage means. Further, the colors corresponding to the colors outside and near the color reproduction range of the image forming apparatus, which are output to the display selecting means, are output by the image forming apparatus using the color patch data stored in the fourth storage means. User selects patch. Since the Lab value of the color of the selected patch has been determined, the output color of the user's preference of the image forming apparatus corresponding to the input outside the color reproduction range of the image forming apparatus and in the vicinity thereof is determined. Then, the information stored in the first storage means and the second storage means is read out, and color conversion is executed based on the grid point output values. As a result, output colors of substantially the same color can be obtained even for inputs 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 colors.

[0032]

【Example】

(Example of Color Conversion Processing) Hereinafter, an embodiment 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 solid figure that is an input color space (XYZ space) is divided into solid blocks of the same type as the concept of the color conversion processing according to the present invention. As shown in FIG. 1, an XYZ space, which is an arbitrary input color space, is added to a solid figure of the same type (in this embodiment,
It should be a cube). Furthermore, the input X,
When obtaining the value of the output P at each of the Y and Z coordinates, select the cube containing the input X, Y and Z coordinates,
The output value at the output P is obtained by linear interpolation based on the output values (known values obtained by a predetermined method) on the eight vertexes of the selected cube.

Here, in the case of conversion into color image data for image formation in the above, X, Y and Z are CIEXY.
Z (CIE 1931 standard color
This corresponds to the input X, Y, Z signals of the image system). Also, the output P is a three-color printer,
Y (yellow), M (magenta), which controls the ink amount,
This corresponds to the C (cyan) signal.

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

[Embodiment 1] This embodiment 1 realizes the first invention and will be described in detail below. (Structure of Embodiment 1) First, a hardware structure for realizing this embodiment will be described. FIG. 2 is a block diagram showing a schematic configuration of a color conversion apparatus according to the first and second embodiments. In the figure, a CPU 201 as a calculation unit that executes control processing for the entire apparatus and an input color space ROM 202 storing output values on grid points in
And an interpolation processing unit 203 for interpolating the grid point output value.

Further, the interpolation processing unit 203, at the time of execution, R
A RAM 204 into which the grid point information stored in the OM 202 is loaded, and a Y processing unit 205 and a M processing unit 206 that respectively generate Y, M, and C signals by referring to the grid point information of the RAM 204 from the input signal. It is composed of a C processing unit 207.

(Processing Operation of Embodiment 1) Next, the color conversion device configured as described above executes the following processing. The grid point information is accumulated in the ROM 202, and the CPU 201
Is the RAM 2 of the interpolation processing unit 203 at the time of execution.
Load (data transfer) to 04. Furthermore, the RAM 20
With reference to the grid point information on 4, the C processing unit 205, the M processing unit 206, and the Y processing unit 207 respectively execute interpolation calculations. 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 ink amount of the printer.

FIG. 3 is a flow chart showing the processing up to the calculation of the grid points (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 the three orthogonal axes (XYZ), and divided into 2 ⁿ areas and shown in FIG. Like (2n +
1) ^Three representative grid points are created (S301). Then, using the conversion formula of the uniform color space shown in (1) below, XYZ / LAB conversion of the representative grid point is performed to calculate the LAB value (S302).

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

L ^* = 116 (Y / Y ₀ ) ¹ / 3−16 a ^* = 500 [(X / X ₀ ) ¹ / 3− (Y / Y ₀ ) ^1/3 ] b ^* = 200 [(Y / Y ₀ ) ¹ / ^3- (Z / Z ₀ ) ^1/3 ] (1)

Subsequently, after the above processing, it is determined whether the representative grid points are included in the color reproduction area of the image forming apparatus, that is, whether the grid points are within the color reproduction area (S303). In such a case, L ^* a ^* b ^* is used for the inside / outside judgment in the color reproduction range ^.
Quantize the color space in the direction of luminance, hue, and saturation, and CMY → L
^{Using an *} a ^* b ^* simulator (described later), data that is the outermost contour of the gamut of the image forming apparatus is created in each quantization space and used.

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

In the present embodiment, the simulation in the above process is CMY → L ^* a ^* b ^* and L ^*.
a ^* b ^* → A neural network trained by a CMY simulator is used. The printer simulator in this embodiment is specifically constructed as follows. That is, a plurality of sets of four output color patches (a single color of CMY and mixed colors) of the image forming apparatus are actually output,
This is measured by a colorimeter to create a plurality of pairs of CMY value-colorimetric value pair data. In addition, input this into CMY → L * a *
The forward direction of b * output and the backward direction of L * a * b * input → CMY output are learned.

On the other hand, if it is determined in step S303 that the representative grid point is outside the color reproduction range of the image forming apparatus, the CMY corresponding to the color that the image forming apparatus cannot output.
An output at each grid point is directly calculated by simulating a fictitious input / output relationship in the image forming apparatus using a simulator constructed by virtually setting values (S305). That is, in step S305, L ^* a of the representative grid point determined to be outside the color reproduction range of the image forming apparatus.
^* b ^* Ink control amount CM that forms a color image with data
Convert to Y.

The stains used in step S305
The simulator is the same as the learning data for construction in step S304.
Different data are used. That is, L in this case
^*a ^*b^*→ The CMY simulator was created artificially
Paired data of CMY values (can be actually output by image forming device
Not L^*a^*b^*CMY corresponding to is virtually determined)
Create multiple sets of^*a^*b^*Input → CMY output
Power) is being learned.

Next, when the output values of all grid points are determined in step S304 or step S305, the calculated grid point output values are filed (S30
6) Then, this is stored in the ROM 202, and this processing ends.

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

[Embodiment 2] This embodiment 2 realizes the second invention and will be described in detail below. (Processing Operation of Second Embodiment) Next, a color conversion process according to the second embodiment will be described using the color conversion device shown in FIG.
FIG. 4 is a diagram illustrating a grid point calculation (color conversion table) according to the second embodiment.
It is a flow chart which shows processing up to. When this process is started, first, the division range of each axis is determined in the input color space of each axis formed by three orthogonal axes (XYZ), and divided into 2 ⁿ areas, which are shown in FIG. Such (2n + 1) ³ representative grid points are created (S401). Then, using the conversion formula (1) of the uniform color space described above, XYZ of the representative grid point
/ LAB conversion is performed to calculate a LAB value (S40
2).

Subsequently, after the above processing, it is determined whether the representative grid point is included in the color reproduction area of the image forming apparatus, that is, whether the grid point is within the color reproduction area (S403). In such a case, L ^* a ^* b ^* is used for the inside / outside judgment in the color reproduction range ^.
Quantize the color space in the direction of luminance, hue, and saturation, and CMY → L
^{Using an *} a ^* b ^* simulator (described later), data that is the outermost contour of the gamut of the image forming apparatus is created in each quantization space and used.

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

In the present embodiment, the simulation in the above processing is CMY → L ^* a ^* b ^* and L ^*.
a ^* b ^* → A neural network trained by a CMY simulator is used. The printer simulator in this embodiment is specifically constructed as follows. That is, a plurality of sets of four output color patches (a single color of CMY and mixed colors) of the image forming apparatus are actually output,
This is measured by a colorimeter to create a plurality of pairs of CMY value-colorimetric value pair data. In addition, input this into CMY → L * a *
The forward direction of b * output and the backward direction of L * a * b * input → CMY output are learned.

On the other hand, when it is determined in step S403 that the color reproduction range 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). The process moves to step S406.

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 as a variable. The grid point output 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) and stored in the ROM 20.
2 is stored, and this processing ends.

Here, the process in step S406 will be described in more detail. FIG. 5 is a block diagram showing a method of calculating output values of grid points 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 into CMY data based on parameters for color conversion, and 502 is L'a 'for CMY data.
It is a CMY → L * a * b * conversion simulator for converting into b ′.

In the above arrangement, the N XYZ values outside the color gamut of the image forming apparatus and near the outermost edge of the color gamut are
The grid points in the color reproduction area of the image forming apparatus are converted into CMY by the color conversion parameter determination unit 501 whose output values are determined as shown in FIG.
L'a 'by the L * a * b * conversion simulator 502
Convert to b '.

Therefore, the color difference error between this L'a'b 'and the Lab value (artificial correspondence) within the color reproduction range of the image forming apparatus corresponding to the input is minimized for all N pieces. First, the output value of the representative grid point of the color conversion parameter determination unit 501, which is determined to be outside the color reproduction range of the image forming apparatus in step S403, is changed and determined.

(Effect of Embodiment 2) Therefore, by the processing of Embodiment 2 described above, it is possible to output the same color as much as possible even for an input outside the color reproduction range of the image forming apparatus, and to reproduce the color of the image forming apparatus. When the shape of the gamut is distorted, color conversion can be performed with high accuracy even if the number of divisions of the input color space is small. Further, even if the input and output data of the image forming apparatus created artificially is considerably inconsistent, it does not diverge when the grid point output value is calculated.

Next, based on the processing described in the above [Embodiment 1] and [Embodiment 2], a color conversion apparatus using a hardware configuration different from this will be described in [Embodiment 3], [Embodiment 4], [Embodiment 5], [Embodiment 6], and [Embodiment 7] will be described in this order.

[Third Embodiment] The third embodiment realizes the third aspect of the present invention, which will be described in detail below. (Structure of Third Embodiment) FIG. 6 is a block diagram showing a schematic structure of a color conversion device according to the third embodiment. In the drawing, C as a calculation means for integrally executing control processing of the entire device is shown.
A PU 601 and a ROM 602 serving as a first storage unit that stores output values on grid points in the input color space.
And an interpolation processing unit 603 for interpolating the grid point output value, and ROM 609 to 611 for storing the output value on the grid point outside the color reproduction area (gamut) as a second storage means. It is composed of a ROM group 608.

Further, the interpolation processing unit 603 executes R
The RAM 604 into which the grid point information stored in the OM 602 and the ROM group 608 is loaded, and R from the input signal
A Y processing unit 605, an M processing unit 606, which generates Y, M, and C signals with reference to the grid point information of the AM 604, respectively.
It is composed of a C processing unit 607.

(Processing Operation of the Third Embodiment) The operation of the color conversion device configured as described above will be described. Output values on grid points in the color reproduction gamut of the image forming apparatus in the input color space are stored in the ROM 602, and the ROMs 609, 610,
The output value on the grid point outside the color reproduction range is stored in 611. That is, a plurality of output value patterns are prepared in the ROM group 608. CPU 601 executes RO during execution
Along with the information of M602, any one of the output values of the grid points outside the color gamut of the ROM group 608 is selected, and the interpolation processing unit 60 is selected.
No. 3 RAM 604 (data transfer). Further, the interpolation processing unit 60 calculates the output value at the output P based on the grid point output value obtained in the first or second embodiment.
Linear interpolation is performed by 3. As a result, the C processing unit 60
5, the M processing unit 606 and the Y processing unit 607 output C signals, M signals, and Y signals for controlling the ink amount of the printer.

(Effect of Third Embodiment) Therefore, with the configuration and the processing thereof according to the third embodiment, it is possible to output substantially the same color even when the input is 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.

[Fourth Embodiment] The fourth embodiment realizes the fourth aspect of the present invention, which will be described in detail below. (Structure of Fourth Embodiment) FIG. 7 is a block diagram showing a schematic structure of a color conversion device according to the fourth embodiment.
PU 701 and ROM 702 as first storage means for storing output values on grid points in the input color space
An interpolation processing unit 703 for interpolating the grid point output value, and a RAM 70 as a second storage unit for temporarily storing the output value on the grid point outside the color reproduction range (gamut).
And 8.

Further, the interpolation processing unit 703 executes R
The RAM 704 to which the grid point information stored in the OM 702 and the RAM 708 is loaded, and RA from the input signal
The Y processing unit 705, the M processing unit 706, and C for generating the Y, M, and C signals respectively with reference to the lattice point information of the M 704.
Processing unit 707.

(Processing Operation of the Fourth Embodiment) The operation of the color conversion device configured as described above will be described. CPU70
In No. 1, the grid point output value is obtained by the method of [Embodiment 1] or [Embodiment 2] described above and is temporarily stored in the RAM 708. Then, the RAM 704 of the interpolation processing unit 703
(Data transfer), and the output value at 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 the C signal, the M signal, and the Y signal for controlling the ink amount of the printer.
Therefore, in this embodiment, the output value on the grid point outside the color reproduction range can be set in the RAM 708 each time.

(Effects of Fourth Embodiment) Therefore, with the configuration and the processing thereof of the fourth embodiment, it is possible to output the same color as much as possible even when the input is outside the color reproduction range of the image forming apparatus. Furthermore, 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.

[Fifth Embodiment] The fifth embodiment realizes the fourth and sixth inventions, and will be described in detail below. (Structure of Fifth Embodiment) FIG. 8 is a block diagram showing a schematic structure of a color conversion device according to the fifth embodiment. In the drawing, C as a calculation means for integrally executing control processing of the entire device is shown.
A PU 801 and a ROM 802 serving as a second storage unit that stores output values on grid points in the input color space.
An interpolation processing unit 803 for interpolating grid point output values, and a second storage for temporarily storing output values on grid points outside the color gamut and within a partial color gamut. A RAM 808 as a means, a RAM 809 as a third storage means for temporarily storing processing information of a grid point in the color reproduction area of the image forming apparatus, and a grid point for a grid point belonging to the color reproduction area. The selection unit 810 is a selection unit for selecting a processing method.

Further, the interpolation processing unit 803 executes R
A RAM 804 loaded with grid point information stored in the OM 802, the RAM 808, and the RAM 809;
Referring to the grid point information of the RAM 804 from the input signal, Y,
It is composed of a Y processing unit 805, an M processing unit 806, and a C processing unit 807 that generate M and C signals, respectively.

(Processing Operation of the Fifth Embodiment) The operation of the color conversion device configured as described above will be described. First, the user selects a desired grid point (basically the grid point near the outermost contour of the color reproduction area) from the grid points in the color reproduction area that were treated as fixed data in the fourth embodiment. The selected grid point information is temporarily stored in the RAM 809. Furthermore, this grid point information is also treated as a grid point outside the color reproduction range in the fourth embodiment. That is, the output values of the grid points outside the color reproduction area and the selected grid points within the color reproduction area can be set each time, and the CPU 801 executes the grid point processing based on the processing of the first embodiment or the second embodiment. The output value is calculated, and the result is temporarily stored in the RAM 808.

Next, when executing the color correction processing, the CPU 801 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 area do not overlap. That is, the grid points outside the color reproduction area of the image forming apparatus and the grid points selected within the color reproduction area are set in the same manner as the grid points outside the color reproduction area in the fourth embodiment, and further, are executed by the CPU 801. Calculated by the processing of Example 1, Example 2, etc., and the result is R
It is temporarily stored in the AM 808. Thereafter, this stored information is loaded into the RAM 804 together with the information in the ROM 802, and the output value at the output P is linearly interpolated by the interpolation processing unit 803 based on the grid point output value.

(Effect of Fifth Embodiment) Therefore, with the configuration and the processing thereof of the fifth embodiment, it is possible to output the same color as much as possible even when the input is outside the color reproduction range of the image forming apparatus. Furthermore, not only the compression in the vicinity of the outermost edge of the color gamut and outside, but also the compression of the entire color space is possible. The degree can be determined by the user.

[Sixth Embodiment] This sixth embodiment realizes the seventh and eighth inventions, and will be described in detail below. (Structure of Sixth Embodiment) FIG. 9 is a block diagram showing the schematic structure of a color conversion device according to the sixth embodiment.
A PU 901 and a ROM 902 serving as a first storage unit that stores output values on grid points in the input color space.
An interpolation processing unit 903 for interpolating the grid point output value, and a second storage for temporarily storing the output value on the grid point outside the color gamut and within the partial color gamut. A RAM 908 as a means and RA as a third storage means for temporarily storing the processing information of the grid points inside and outside the color reproduction area of the image forming apparatus.
M909 and RAM91 as a fourth storage means for temporarily storing the input color image data
0.

Further, the interpolation processing unit 903 makes the R
OM902, RAM908, RAM909, and RA
R to which the grid point information stored in M910 is loaded
It is composed of an AM 904, a Y processing unit 905, an M processing unit 906, and a C processing unit 907 that respectively generate Y, M, and C signals from an input signal by referring to lattice point information of the RAM 904.

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

Further, the CPU 901 compares the created color map with the color gamut of the image forming apparatus, selects a grid point necessary for outputting the input image among grid points outside the color gamut, and Is stored in the RAM 909. Also, C
Since the PU 901 uses the uniform color space such as L * a * b * as the input space in this embodiment, the grid of the divided space inside the space where the input image data is distributed outside the color reproduction range (radiation axis direction). A point, that is, a grid point in the color reproduction area treated as fixed data in the fourth embodiment is selected.

Then, the selected grid point information is also RA.
It is temporarily stored in M909. The output values on the grid points (a part of the grid points inside and outside the color reproduction area) stored in the RAM 909 are calculated by the CPU 901 in the processes of the first and second embodiments and are stored in the RAM 908.

Next, when executing the color correction processing, the CPU 901 refers to the grid point information stored in the RAM 909 and loads the grid point output value data in the color reproduction area into the RAM 904 so that they do not overlap. That is, only the grid points outside the color reproduction area of the image forming apparatus and the grid points selected within the color reproduction area are calculated by the CPU 901 by the processing of the first and second embodiments, and the result is temporarily stored in the RAM 908. To be done. After that, RAM with the information of ROM902
The output value at the output P is obtained by linear interpolation in the interpolation processing unit 903 based on the grid point output value.

(Effect of Sixth Embodiment) Therefore, with the configuration and the processing thereof according to the sixth embodiment, it is possible to output the same color as much as possible even when the input is outside the color reproduction range of the image forming apparatus. It is possible to perform the optimum compression of the entire color space corresponding to the color image. Moreover, since the output values on the unused grid points are not calculated, the processing time can be shortened.

[Seventh Embodiment] This seventh embodiment realizes the ninth invention, which will be described in detail below. (Structure of Seventh Embodiment) FIG. 10 is a block diagram showing a schematic structure of a color conversion apparatus according to the seventh embodiment. In the figure, a CPU 1001 as a calculation means for integrally executing control processing of the entire apparatus, ROM 10 as first storage means for storing output values on grid points in the input color space
02, and an interpolation processing unit 1003 for interpolating the grid point output value
And a RAM 1008 as second storage means for temporarily storing output values on the grid points outside the color reproduction area (gamut) and within a part of the color reproduction area, and within the color reproduction area of the image forming apparatus. RAM 10 as a third storage means for temporarily storing the processing information of the lattice points in
09, a ROM 1010 as a fourth storage means for storing patch creation data used for color selection, and a CRT (or control panel) 1011 as a display selection means used for color selection. Further, 1012 is an image forming apparatus.

Further, the interpolation processing unit 1003 has a RAM 1004 to which grid point information stored in the ROM 1002, the RAM 1008, the RAM 1009, and the RAM 1010 is loaded at the time of execution, and the RAM 100 from the input signal.
It is composed of a Y processing unit 1005, an M processing unit 1006, and a C processing unit 1007 that respectively generate Y, M, and C signals with reference to the lattice point information of No. 4.

(Processing Operation of the Seventh Embodiment) 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 the grid point near the outermost edge of the color reproduction area) from the grid points in the color reproduction area. RA this selected information
It is stored in M1009. Further, the selected grid point is calculated by the CPU 1001 as shown below,
It is stored in the RAM 1008.

That is, the grid points in the above are input / output data artificially created so that the input outside the color reproduction area of the image forming apparatus and in the vicinity thereof correspond to the output of the image forming apparatus, as described in the second embodiment. Is calculated by changing the grid point output value set as a variable so that the reproduction error (color difference) of the overall color conversion result is minimized.

Further, when the grid points are calculated, the Lab within the color reproduction range of the image forming apparatus corresponding to the input in FIG.
It is necessary to create a value (corresponding artificially). In this embodiment, in order to create paired data of Lab values (FIG. 5) within the input-color reproduction range, colors output to the CRT (or control panel) 1011 (outside of the color reproduction range of the image forming apparatus and in the vicinity thereof). The user selects a color corresponding to the color of the color) from the patch (created by the data of the ROM 1010) output by the image forming apparatus 1012.

As described above, the color of the selected patch is La
Since the b value is fixed, the output color of the image forming apparatus, which is the user's preference, is determined according to the input outside the color reproduction range of the image forming apparatus and in the vicinity thereof. After that, as shown in FIG. 5, the output value of the representative grid point is changed and determined so that the overall color difference error is minimized for all N pieces. The color of the sample (the color output to the CRT 1011) is set by the CPU 1001 in the RAM 10 as necessary.
It is arbitrarily selected corresponding to the information of 09.

The output value calculated by the above process is R
It is temporarily stored in AM 1008. The stored output value is loaded into the RAM 1004 together with the information in the ROM 1002. Then, the interpolation processing unit 1003 outputs P based on this load information, that is, the grid point output value.
The output value at is obtained by linear interpolation.

(Effect of Seventh Embodiment) Therefore, with the configuration and the processing thereof of the seventh embodiment, it is possible to output the same color as much as possible even when the input is out of the color reproduction range of the image forming apparatus. Can freely decide the compression of the input color space while actually checking the desired color.

[0087]

As described above, according to the color conversion apparatus (Claim 1) of the present invention, the actual measured values of the input / output color patch only for the grid points belonging to the color reproduction range of the image forming apparatus. L * a * using the simulator built in
Ink control amount CMY for forming a color image from b * data
Convert to. For grid points outside the color gamut of the image forming apparatus, L * a * b * data is obtained using a simulator in which CMY values corresponding to colors that the image forming apparatus cannot output grid point output values are virtually set. The ink control amount CMY for forming a color image is converted. Therefore, it is possible to obtain an output color that is substantially equivalent to an input outside the color reproduction range of the image forming apparatus. Further, even when the input color space is subdivided and the number of grid points is increased, a huge amount of calculation for calculating the output value on the grid points is eliminated, and the processing time can be shortened.

Further, according to the color conversion apparatus (Claim 2) of the present invention, the simulator constructed by the measured values of the actual input / output color patch is used only for the grid points belonging to the color reproduction range of the image forming apparatus. , L * a * b * data is converted into an ink control amount CMY for forming a color image. For grid points outside the color gamut of the image forming apparatus, input / output data that is artificially created so that the input outside the color gamut of the image forming apparatus corresponds to the output of the image forming apparatus is used. The L * a * b * data is converted into an ink control amount CMY that forms a color image by varying the grid point output value set as a variable parameter so that the reproduction error (color difference) of the conversion result is minimized. Therefore, it is possible to obtain an output color that is substantially equivalent to an input outside the color reproduction range of the image forming apparatus. Further, when the shape of the color gamut of the image forming apparatus is distorted, highly accurate color conversion can be realized even if the number of divisions of the input color space is small.

According to the color conversion device of the present invention (claim 3), the grid point information (grid point output value) of the grid points included in the color reproduction area of the image forming apparatus does not change. Area), and the grid point information (grid point output value) of the grid points outside the color reproduction area of the image forming apparatus is set as a storage area (variable area) that can be reset or selected. The lattice point information stored in the second storage means is read out, and the grid point information stored in the first storage means and the second storage means is read out to perform the process of the first invention, that is, inside and outside the reproduction range of the grid points. Since the color conversion processing is executed based on the grid point output value obtained by simulation according to the above, 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.

Further, according to the color conversion apparatus of the present invention (claim 4), the grid point information (grid point output value) of grid points included in the color reproduction area of the image forming apparatus does not change (fixed area). Area), and the grid point information (grid point output value) of grid points outside the color reproduction area of the image forming apparatus is stored as a storage area (variable area) that can be reset or selected. The lattice point information stored in the second storage means is read out, and the grid point information stored in the first storage means and the second storage means is read out to perform the process of the second invention, that is, inside and outside the reproduction range of the grid points. Since the color conversion processing is executed based on the grid point output value obtained by simulation according to the above, 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.

Further, according to the color conversion device of the present invention (claim 5), the user selects a desired grid point from the grid points in the color reproduction area which are treated as fixed data. Then, the output values of the grid points outside the color reproduction area and the selected grid points within the color reproduction area can be set each time,
The value obtained by executing the color conversion process based on the grid point output value obtained by simulation according to the processing of the first invention, that is, the inside and outside of the reproduction range of the grid point
It is stored in the storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read out without overlapping and the color conversion processing is executed, so that it is outside the color reproduction area of the image forming apparatus. It is possible to obtain an output color having substantially the same color for the input of. Further, not only the compression of 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.

Further, according to the color conversion device of the present invention (claim 6), the user selects a desired grid point from the grid points in the color reproduction area which are treated as fixed data. Then, the output values of the grid points outside the color reproduction area and the selected grid points within the color reproduction area can be set each time,
The value obtained by performing the color conversion process based on the grid point output value obtained by simulation according to the process of the second invention, that is, the inside and outside of the reproduction range of the grid point
It is stored in the storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read out without overlapping and the color conversion processing is executed, so that it is outside the color reproduction area of the image forming apparatus. It is possible to obtain an output color having substantially the same color for the input of. Further, not only the compression in the outermost part of the color reproduction range and the outside, but also the compression of the entire color space can be realized, and the degree can be selected by the user.

According to the color conversion device of the present invention (claim 7), the input color image signal data is converted into the fourth color image signal data.
The calculation means detects which area of the input color space the data belongs to, and counts the number of pixels for each area to create a color map. To do. Further, the calculation means compares the color map with the color reproduction area of the image forming apparatus, selects a grid point necessary for outputting the input image among grid points outside the color reproduction area, and selects the grid point from the third color map. It is stored in the storage means. Further, the calculation means selects a divided space inside the space where the input image data is distributed outside the color reproduction area (radial axis direction), 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 grid point output value obtained by the process of the first invention, that is, the simulation inside or outside the reproduction range of the grid point. The value obtained by executing the color conversion process is stored in the second storage means. Next, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read out without overlapping and the color conversion processing is executed, so that it is outside the color reproduction area of the image forming apparatus. It is possible to obtain an output color having substantially the same color for the input of.
Further, it is possible to realize optimal compression of the entire color space corresponding to the input color image. Furthermore, since the output values on the unused grid points are not calculated, the overall processing time can be shortened.

According to the color conversion device (claim 8) of the present invention, the input color image signal data is converted into the fourth color image signal data.
The calculation means detects which area of the input color space the data belongs to, and counts the number of pixels for each area to create a color map. To do. Further, the calculation means compares the color map with the color reproduction area of the image forming apparatus, selects a grid point necessary for outputting the input image among grid points outside the color reproduction area, and selects the grid point from the third color map. It is stored in the storage means. Further, the calculation means selects a divided space inside the space where the input image data is distributed outside the color reproduction area (radial axis direction), 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 grid point output value obtained by the process of the second invention, that is, the simulation based on the inside or 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, by referring to the processing information stored in the third storage means, the grid point output value data in the color reproduction area is read out without overlapping and the color conversion processing is executed, so that it is outside the color reproduction area of the image forming apparatus. It is possible to obtain an output color having substantially the same color for the input of.
Further, it is possible to realize optimal compression of the entire color space corresponding to the input color image. Furthermore, since the output values on the unused grid points are not calculated, the overall processing time can be shortened.

According to the color conversion apparatus of the present invention (claim 9), the user selects a desired grid point from the grid points in the color reproduction area and stores it in the third storage means. Keep it. The grid point output value of the selected grid point is calculated by the process of claim 2, and the value is stored in the second storage means. Further, the colors corresponding to the colors outside and near the color reproduction range of the image forming apparatus, which are output to the display selecting means, are output by the image forming apparatus using the color patch data stored in the fourth storage means. User selects patch. Since the Lab value of the color of the selected patch has been determined, the output color of the user's preference of the image forming apparatus corresponding to the input outside the color reproduction range of the image forming apparatus and in the vicinity thereof is determined. Then, the information stored in the first storage means and the second storage means is read out, and color conversion is executed based on the grid point output values. Therefore, it is possible to obtain an output color that is substantially equal to the input color outside the color reproduction range of the image forming apparatus. Also, the user can freely set the compression of the input color space while actually confirming the color himself.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an example in which a solid figure which is an input color space (XYZ space) is divided into solid blocks of the same type as a concept of color conversion processing according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a color conversion device according to the first and second embodiments.

FIG. 3 is a grid point calculation (color conversion table) according to the first embodiment.
It is a flow chart which shows processing up to.

FIG. 4 is a grid point calculation (color conversion table) according to the second embodiment.
It is a flow chart which shows processing up to.

FIG. 5 is a block diagram showing a method of calculating output values of grid points outside the color reproduction range of the image forming apparatus according to the present embodiment.

FIG. 6 is a block diagram illustrating a schematic configuration of a color conversion device according to a third embodiment.

FIG. 7 is a block diagram illustrating a schematic configuration of a color conversion device according to a fourth embodiment.

FIG. 8 is a block diagram illustrating a schematic configuration of a color conversion device according to a fifth embodiment.

FIG. 9 is a block diagram illustrating a schematic configuration of a color conversion device according to a sixth embodiment.

FIG. 10 is a block diagram illustrating a schematic configuration of a color conversion device according to a seventh embodiment.

[Explanation of symbols]

201, 601, 701, 801, 901, 1001
CPU 608 ROM group 708, 808, 809, 908, 909, 910, 1
RAM 810 Selector 1010 ROM 1011 CRT 1012 Image forming apparatus

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroki Kuboen 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) Etsuro Morimoto 1-3-6 Nakamagome, Ota-ku, Tokyo Shares Company Ricoh

Claims (9)

[Claims] 1. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. Thus, in the color conversion device that executes color conversion, it is determined whether or not the grid point is included in the color reproduction area of the color image formation difference, and in the first case where the grid point is in the color reproduction area. Simulating the actual input / output relationship in the color image forming apparatus, and in the second case where the grid points are outside the color reproduction area, input outside the color reproduction area of the color image formation apparatus and in the vicinity thereof is performed. A color conversion device comprising a calculation means for calculating grid point output values by performing simulation so as to correspond to the input / output relationship of the color image forming device. 2. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. Thus, in the color conversion device that executes color conversion, it is determined whether or not the grid point is included in the color reproduction area of the color image forming apparatus, and in the first case where the grid point is within the color reproduction area. Simulating the actual input / output relationship in the color image forming apparatus, and 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 to form the color image. Outputs on the grid points, which are variables outside the color reproduction range of the apparatus and the vicinity thereof, are used as variables so that the reproduction error (color difference) of the entire color conversion result is minimized by using the input / output data of the color image forming apparatus. By changing the value, A color conversion device, comprising: a calculating unit that calculates each grid point output value. 3. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the grid outside the color reproduction area of the color image forming apparatus. Second storage means for storing a plurality of patterns of output values on the dots, and determining whether or not the grid points on the three-dimensional input color space are included in the color reproduction area of the color image forming apparatus, In the first case where the grid point is 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 point is outside the color reproduction range, Of the color image forming apparatus And a calculation unit that calculates grid point output values by simulating inputs outside the color reproduction range and in the vicinity thereof so as to correspond to the input / output relationship of the color image forming apparatus, and stores the values in the second storage unit. Any one of the stored patterns 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. Converter. 4. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming device, and the grid outside the color reproduction area of the color image forming device. Second storage means for storing a plurality of patterns of output values on points, and determining whether or not the grid points on the three-dimensional input color space are included in the color gamut 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 in the second case where the grid points are outside the color reproduction range, Change the output value on the grid point The input and output of the color image forming apparatus outside and in the vicinity of the color reproduction area of the color image forming apparatus are input and output using the color image forming apparatus. And calculating means for respectively calculating the grid point output value by varying the output value on the grid point, the pattern being stored in any one of the patterns stored in the second storage means and the first storage means. A color conversion device, characterized in that the stored grid point information is read and color conversion is executed based on the grid point output value calculated by the calculation means. 5. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion by the above, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the outside and a part of the color reproduction area of the color image forming apparatus The second storage means for temporarily storing the output value on the grid point in the color reproduction area, and the desired grid point from the grid points to which the color reproduction area belongs belong to the processing method of the grid point. Selection means for selection, third storage means for storing the processing information selected by the selection means, and grid point information selected by the selection means is read out from the third storage means to obtain the color image. Forming device Is included in the color reproduction range, and when the grid points are in the color reproduction range in the first case,
Simulating the actual input / output relationship in the color image forming apparatus, and in the second case where the grid points are outside the color reproduction area, the input outside the color reproduction area of the color image formation apparatus and in the vicinity thereof is A simulation is performed so as to correspond to the input / output relationship of the color image forming apparatus, the grid point output values are respectively calculated, and the calculation means is stored in the second storage means. A color conversion device, which reads out the grid point information stored in the second storage means and performs color conversion based on the grid point output value calculated by the calculation means. 6. An output value of a color image forming device in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion by the above, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the outside and a part of the color reproduction area of the color image forming apparatus The second storage means for temporarily storing the output value on the grid point in the color reproduction area, and the desired grid point from the grid points to which the color reproduction area belongs are selected, and a processing method for the grid point is described. Selection means to be selected, third storage means for storing the processing information selected by the selection means, grid point information selected by the selection means is read from the third storage means, and the color image is displayed. Forming device Is included in the color reproduction range, and when the grid points are in the color reproduction range in the first case,
Simulating the actual input / output relationship in the color image forming apparatus, and 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 color image forming apparatus is used. Input and output of the color image forming apparatus outside the color reproduction range and in the vicinity thereof are used so that the reproduction error (color difference) of the entire color conversion result is minimized.
Calculating means for respectively calculating output values on the grid points by varying output values on the grid points as variables.
The color conversion device which reads out the grid point information stored in the storage means and the second storage means, and executes color conversion based on the grid point output value calculated by the calculation means. 7. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion by the above, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the outside and a part of the color reproduction area of the color image forming apparatus Second storage means for temporarily storing the output values on the grid points within the color reproduction area, and third storage means for temporarily storing the processing information of the grid points within the color reproduction area of the color image forming apparatus. , Fourth storage means for temporarily storing information of the input color image signal, and which of the input color spaces divided into a plurality of areas from the image data stored in the fourth storage means Detect if it belongs to a region The number of pixels for each area is counted to create a color map, the color map is compared with the color reproduction area of the color image forming apparatus, and the input image is output in a grid point outside the color reproduction area. The necessary grid points are selected, the grid points are stored in the third storage means, and it is further determined whether or not the grid points are included in the color reproduction area of the color image forming apparatus. In the first case where is 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 point is outside the color reproduction range, the color image is reproduced. The input outside the color gamut of the forming apparatus and in the vicinity thereof is simulated so as to correspond to the input / output relationship of the color image forming apparatus, the grid point output values are calculated, and these are stored in the second storage means. Calculation means to Wherein the first
The color conversion device which reads out the grid point information stored in the storage means and the second storage means, and executes color conversion based on the grid point output value calculated by the calculation means. 8. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set at a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion by the above, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the outside and a part of the color reproduction area of the color image forming apparatus Second storage means for temporarily storing the output values on the grid points within the color reproduction area, and third storage means for temporarily storing the processing information of the grid points within the color reproduction area of the color image forming apparatus. , Fourth storage means for temporarily storing information of the input color image signal, and which of the input color spaces divided into a plurality of areas from the image data stored in the fourth storage means Detect if it belongs to a region The number of pixels for each area is counted to create a color map, the color map is compared with the color reproduction area of the color image forming apparatus, and the input image is output in a grid point outside the color reproduction area. The necessary grid points are selected, the grid points are stored in the third storage means, and it is further determined whether or not the grid points are included in the color reproduction area of the color image forming apparatus. In the color reproduction area, in the first case, the actual input / output relationship in the color image forming apparatus is simulated, and in the second case where the grid point is outside the color reproduction area, the grid point The output value of is used as a variable, and the input outside the color reproduction area of the color image forming apparatus and its vicinity is used by using the input / output data of the color image forming apparatus so that the reproduction error (color difference) of the entire color conversion result is minimized. , The above-mentioned lattice point calculation as a variable And calculating means for storing this in the second storage means, reading out the grid point information stored in the first storage means and the second storage means, and the grid calculated by the calculation means. A color conversion device, which performs color conversion based on a point output value. 9. An output value of a color image forming apparatus in an arbitrary three-dimensional input color space is interpolated with a grid point output value set to a grid point in the three-dimensional input color space divided into three-dimensional figures. In the color conversion device for executing the color conversion by the above, the first storage means for storing the grid point information belonging to the color reproduction area of the color image forming apparatus, and the outside and a part of the color reproduction area of the color image forming apparatus Second storage means for temporarily storing the output values on the grid points within the color reproduction area, and third storage means for temporarily storing the processing information of the grid points within the color reproduction area of the color image forming apparatus. A fourth storage means for storing color patch data for color selection, a display selection means for displaying colors outside and near the color reproduction range of the color image forming apparatus for color selection, and the display selection Output to the means The colors corresponding to the colors outside and near the color reproduction range of the color image forming apparatus are output to the color image forming apparatus as the color patches stored in the fourth storage unit, and the desired color patch is selected. Storing the selection information in the third storage means, calculating the selected desired grid point, and further determining whether or not the grid point is included in the color reproduction area of the color image forming apparatus. Then
In the first case where the grid point is within the color reproduction range, the actual input / output relationship in the color image forming apparatus is simulated, and the grid point is outside the color reproduction range.
In this case, the output value on the grid point is used as a variable, and the input and output outside the color reproduction area of the color image forming apparatus and in the vicinity thereof are used as input and output data of the color image forming apparatus, and the reproduction error of the entire color conversion result is obtained. A calculation means for varying output values on the grid points, which are variables, so as to minimize (color difference), calculating grid point output values, and storing the calculated output values in the second storage means. , Reading the grid point information stored in the first storage means and the second storage means,
A color conversion device, which executes color conversion based on the grid point output values calculated by the calculation means.