JPH08163382A - Color image forming device - Google Patents

Abstract

PURPOSE: To easily and accurately generate color correction data by mixing three primary color dyes of the same quantity to obtain the color vector of a color sample and setting correction data for color correction data generation based on the mixture ratio of dyes which is so set that this color vector is 0. CONSTITUTION: Color data of recording paper read by a read means is converted to color data of the colorimetric system based on three attributes of color by the color data conversion means of a correction coefficient setting means 115, thereby generating a color vector in the hue-saturation plane system of recording paper. The mixture ratio of respective toners is set based on this color vector of the color sample by a mixture ratio setting means 118 so that the color vector is 0. In this constitution, an accurate achromatic color is formed on recording paper because the mixture ratio of respective toners is corrected so as to prevent, for example, a reddish achromatic color from being formed by an influence of the color of recording paper.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus such as a color copying machine.

[0002]

2. Description of the Related Art Conventionally, a color original is optically read by a scanner section having a CCD (electrically coupled element),
The read image data is R (red), G (green) and B
2. Description of the Related Art A color image forming apparatus is known in which a color image is formed by converting into an additive color mixture of three primary color signals of (blue) and forming a color image based on the signals. R output from the scanner section,
The G and B three-primary color signals have a complementary color relationship with these three primary colors.
After being converted into subtractive color mixture primary color data of (cyan), M (magenta), and Y (yellow), the data is output to the printer unit of the image forming apparatus.

In the printer section, the surface of the photosensitive member is searched by a laser beam which is modulated based on image data of cyan, for example, and an electrostatic latent image corresponding to cyan is formed on the surface of the photosensitive member. This electrostatic latent image is
A toner image is developed with a dye consisting of cyan toner, and this toner image is transferred to recording paper, and then toner images of each color are similarly recorded on the recording paper corresponding to the magenta color data and the yellow image data. A color image is formed by being transferred in an overlapping manner.

[0004]

In the color image forming apparatus having the above-mentioned structure, the cyan, magenta and yellow toners used for forming the color image contain a small amount of impurities. It is unavoidable that the color reproducibility of the image is deteriorated due to the color deviation of the color image formed on the sheet from the color of the original.

In particular, when the above toners are uniformly blended to form an achromatic color such as gray, it is difficult to form an accurate achromatic color due to the presence of the above-mentioned impurities, and a reddish tint is produced. There is a problem that inaccurate achromatic colors such as gray, bluish gray or yellowish gray are easily formed.

In order to prevent the above-mentioned adverse effect, an image formed by toner of each color is compared with a standard color, so that the hue value of each color is in any direction on the hue circle due to mixing of impurities. It is conceivable that the color reproducibility is improved by measuring whether or not there is a degree of deviation, and adjusting the amount of toner adhered to the surface of the photoconductor drum based on the color correction data created based on this measurement data.

However, since the hue value shift amount and the like differ depending on the type of each toner, it is extremely difficult to accurately measure this value, and accurate color correction data is created based on this measurement value. Had a problem that it required complicated work and skill.

The present invention has been made to solve the above problems, and provides a color image forming apparatus capable of easily and accurately creating color correction data to improve the color reproducibility of a toner image. The purpose is to do.

[0009]

The invention according to claim 1 is
In a color image forming apparatus that forms a color image by mixing three primary color dyes, a reading unit that reads image data of a color sample formed by mixing equal amounts of the above three primary color dyes, and a reading unit that reads the image data. Color data conversion means for obtaining the color vector of the color sample in the hue-saturation plane system by converting the image data into color data of the color system based on the three attributes of color, and the color data conversion means. Further, based on the color vector of the color sample, there is provided a compounding ratio setting means for setting the compounding ratio of each dye so that this color vector is set to 0, and the compounding ratio of the dye set by the compounding ratio setting device is set. It is configured to set a correction coefficient for creating color correction data.

According to a second aspect of the invention, in a color image forming apparatus for forming a color image by mixing three primary color dyes, a reading means for reading the image data of the three primary color dyes, and image data read by the reading means. In the hue-saturation plane system by synthesizing the color data of the three primary color dyes based on the output data of the color data conversion means and the color data conversion means for converting the color data into the color data of the color system based on the three attributes of color. A composite vector computing means for computing a composite vector of the three primary color dyes, and a blending ratio setting means for setting the blending ratio of each dye so that the composite vector becomes 0 based on the above-mentioned composite vector obtained by the composite vector computing means. Is provided, and the correction coefficient for creating the color correction data is set according to the mixture ratio of the dye set by the mixture ratio setting means. Are those that you have configured so that.

According to a third aspect of the invention, in an image forming apparatus for forming a color image by transferring dyes of three primary colors onto a recording paper, a reading means for reading the color data of the recording paper and a reading means for reading the color data. Color data conversion means for obtaining the color vector of the recording paper in the hue-saturation plane system by converting the color data of the recording paper into color data of the color system based on the three attributes of the color, and this color data conversion means Based on the color vector of the recording paper obtained by the above, there is provided a blending ratio setting means for setting the blending ratio of each dye so that this color vector becomes 0, and the blending of the dye set by this blending ratio setting means. The correction coefficient for creating the color correction data is set according to the ratio.

[0012]

According to the invention described in claim 1, an achromatic color sample is formed by mixing equal amounts of the three primary color dyes at the time of manufacturing the color image forming apparatus, and the image data of the color sample is obtained. After being read by the reading means, a color correction coefficient is set based on the color vector obtained by converting this image data into color data of the color system based on the three attributes of color, and the color correction coefficient is created according to this correction coefficient. The compounding amount of the dye is corrected based on the color correction data.

According to the second aspect of the invention, the color samples of the three primary color dyes formed on the recording paper are sequentially read by the image reading means when the color image forming apparatus is manufactured, and the color data is obtained. The color vector of each color sample is obtained by converting the color data of the color system based on the three attributes of color. Then, the color correction coefficient is set based on the combined vector obtained by combining the color vectors, and the compounding amount of the dye is corrected based on the color correction data created according to the correction coefficient.

According to the third aspect of the present invention, after the color data of the recording paper to be used is read by the reading means at the time of periodic inspection of the color image forming apparatus, the color data is converted into three color attributes. The color correction coefficient is set based on the color vector obtained by converting to the color data of the color system based on the color data, and the compounding amount of the dye is corrected based on the color correction data created according to this correction coefficient. Become.

[0015]

1 and 2 show an embodiment of a color image forming apparatus 1 according to the present invention. The color image forming apparatus 1 comprises a color copying machine having a scanner section 2 for reading a color original document and a printer section 3 for forming a color image on a recording sheet based on the image data read by the scanner section 2. There is.

The scanner unit 2 is provided in the upper portion of the main body of the color image forming apparatus 1, and the printer unit 3 is provided in the lower portion of the scanner unit 2. A platen glass 4 on which an original is set and an operation panel 5 are provided on the upper surface of the scanner unit 2, and an original retainer 6 is provided on the platen glass 4 so as to be openable and closable. The operation panel 5 is provided with operation switches such as a copy key, a numeric keypad, a clear key and a density adjustment key, which are related to the copy operation.

Below the platen glass 4 is provided an image reading section 9 which reciprocates in the direction of arrow A from the home position to the end position of the maximum document size.
The image reading unit 9 includes an illumination lamp 91 that illuminates an original placed on the platen glass 4, a reflector 92, and a SELFOC lens 93 that forms an image of reflected light from the original on an image sensor 94. An image pickup device 94 including a CCD or the like for reading an image of an original image and a conversion circuit 95 for converting RGB image data read by the image pickup device 94 into CMY image data are provided.

The image pickup device 94 has an R for each pixel.
(Red), G (green), B (blue) color filters,
The image at the same pixel position is separated into image signals (analog signals) of R, G, B color components and output. Further, the conversion circuit 95 performs A / D conversion on the R, G, and B image signals, and then the C (cyan), M (magenta), and Y (yellow) image data which are the three primary colors of the subtractive color mixture method. It is configured to be converted into and output.

The RGB image data is converted into C, M, Y image data by the following equation.

C = (1-Ri / R0) M = (1-Gi / G0) Y = (1-Bi / B0) C, M, and Y are the densities of the three primary colors in the normalized subtractive color mixture method. (Gradation) levels, Ri, Gi, and Bi are density (gradation) levels of the three primary colors in the read additive color mixing method,
R0, G0, and B0 are maximum density (gradation) levels in the A / D conversion processing.

In the above equation, for example, when the image data is composed of 8-bit data, the image density is represented by a resolution of 256 gradations, and the maximum density levels R0, G0, B0 are 25.
5, the image data of C, M, Y is C = (1-
Ri / 255), M (1-Gi / 255), Y = (1-
Bi / 255).

The image reading unit 9 reads a document image in line units while moving forward from the home position to the end position of the document size, and converts this image signal into C, M, Y image data as described above. Then, the image is output to the image processing unit 10 provided in the printer unit 3.

The printer unit 3 includes the image processing unit 10 and
An exposure unit 11 that exposes the photosensitive drum 121 to form a latent image of a document image, a transfer unit 12 that forms a color image of a document on a recording sheet, and feeding and discharging of the recording sheet to the transfer unit 12. A recording paper transport unit 13 for carrying out the above and a discharge tray 8 for storing the discharged recording paper are provided.

The exposure unit 11 includes a laser light emitter 111 that emits laser light modulated based on image data,
It is composed of a polygon mirror 112 that scans the surface of the photoconductor drum 121 in the axial direction with the laser light, and a mirror 113 that guides the laser light to the photoconductor drum 121.

The transfer section 12 includes a photoconductor drum 121 that produces a latent image and a color image of a document, a charging device 122 that charges the photoconductor drum 121, and the photoconductor drum 1.
Developing device 123 for visualizing the latent image formed on 21
And a cleaning device 124 for removing residual toner adhering to the photosensitive drum 121. Further, the recording paper is provided on the downstream side of the developing device 123, and
A transfer drum 133 that contacts the peripheral surface of the sheet 1 and feeds the sheet is disposed.

The photosensitive drum 121 is constructed to rotate in the direction of arrow B at a predetermined speed when forming a latent image and a visible image. On the other hand, the transfer drum 133 is rotationally driven in the direction of arrow D in synchronization with the photosensitive drum 121, and the rotational speed is controlled so that the peripheral speed of the transfer drum 133 becomes the same as the peripheral speed of the photosensitive drum 121. It is like this.

The developing device 123 includes four developing devices 123a to 123a arranged vertically and integrally driven up and down.
Each of the developing devices 123a to 123d has four types of color toners of cyan, magenta, yellow, and black from the top. The developing devices 123a to 123d are installed so as to be in contact with the peripheral surface of the photosensitive drum 121, respectively.
3d is sequentially moved up and down to the developing position to form a toner image in the order of cyan, magenta, yellow, and black, so that the latent image formed on the photosensitive drum 121 is made visible.

The recording paper transport unit 13 has paper feed cassettes 131a and 131b in which recording papers are stored below the printer unit 3.
And a guide mechanism 13 for guiding the recording paper conveyed from the paper feed cassettes 131a and 131b to the transfer drum 133.
2, a separation claw 134 for separating the recording paper electrostatically adsorbed on the surface of the transfer drum 133, a conveyance mechanism 135 for conveying the separated recording paper to the fixing device 136, and fixing the toner image formed on the recording paper. And a fixing device 136 that operates.

Inside the transfer drum 133,
A transfer device 133a for transferring the toner image formed on the photosensitive drum 121 to a recording sheet by high-frequency discharge is provided,
Inside the transfer drum 133 and outside, a pair of separators 133b for separating the recording paper from the transfer drum 133 by corona discharge are arranged opposite to each other.

The separating claw 134 is arranged downstream of the separator 133b. A cleaning device 137 for cleaning the surface of the transfer drum 133 after separating the recording paper is provided around the transfer drum 133 and on the downstream side of the separation claw 134.

In the above configuration, the R, G, B image data of the document read by the image reading unit 9 of the scanner unit 2 is converted into C, M, Y image data, and then the image processing unit 10 is processed. The image is output and the predetermined image signal processing is performed by the image processing unit 10. The image processing unit 10
While correcting the C, M, and Y image data, BK
By creating (black) image data and sequentially outputting these image data to the printer unit 3, a color image is formed on the recording paper based on the image data.

When forming the above-mentioned color image, first, the laser beam modulated based on the cyan image data is irradiated from the exposure unit 11 to the photosensitive drum 121 charged to a predetermined potential by the charging device 122, and the original is read. An electrostatic latent image corresponding to the cyan component of the image is formed. The laser light is synchronized with the peripheral speed of the photoconductor drum 121,
The surface of the is scanned while being scanned in the raster direction.

At the developing position, the photosensitive drum 1
The electrostatic latent image formed on 21 is developed into a toner image by electrostatically adsorbing the cyan toner contained in the developing device 123a of the developing device 123. Then, the toner image is pressed against the recording paper fed by the transfer drum 133 at the transfer position, so that the image of the cyan component is transferred onto the recording paper.

The surface of the photoconductor drum 121 is cleaned by a cleaning device 124 after image formation, and then charged again to a predetermined potential by a charging device 122, which corresponds to the magenta component of the original image in the same manner as described above. An electrostatic latent image is formed and a toner image is formed with magenta toner. The magenta toner image is transferred again to the recording sheet fed to the transfer position by the transfer drum 133.

Thereafter, in the same manner, the toner images of the yellow component and the black component of the original image are sequentially transferred to the recording paper, and the image formation of the color image is completed. The recording paper adsorbed on the transfer drum 133 is peeled off by the separation claw 134, conveyed to the fixing device 136 by the conveying mechanism 135, where the transferred toner image is fixed, and then discharged to the discharge tray 8. It

The image processing section 10 includes an input processing circuit 101 and a printer color correction circuit 10 as shown in FIG.
2, a data selector circuit 103, an output format processing circuit 104, a filter processing circuit 105, a multi-value dither processing circuit 106, and an image processing CPU 107.

The input processing circuit 101 has a channel synthesizing circuit 108 for separating the image data output from the CCD of the scanner section 2 into R, G, B image data, and each of the channel synthesizing circuits 108 output. A pseudo-correction circuit 109 that corrects variations in sensitivity of each pixel of the sensor by correcting the data by shading, and unevenness of the illumination, and the corrected R, G, and B image data to C,
An image data conversion circuit 110 for converting the image data of M, Y, and BK is provided.

The printer color correction circuit 102 is configured to perform masking correction on the input C, M, and Y image data in consideration of the characteristics of C, M, and Y color toners. The BK image data at the pixel position of the black portion is directly output to the data selector circuit 103 without being corrected.

The data selector circuit 103 outputs C, M, Y, and C signals output to the laser oscillator 111 of the printer section 3.
This is a circuit for setting the image data of each color of BK in the order of C, M, Y, BK. Further, the output format processing circuit 104 processes each data for subjecting an image to italic and black-and-white inversion processing according to an input signal of the operation panel 5 and processing data such as composition, enlargement / reduction and movement. Is provided.

The filter processing circuit 105 is a circuit for correcting the image quality of the image formed on the recording paper. For example, it is configured to perform processing for facilitating the separation of the image area between the binary image and the halftone image. Further, the multi-level dither processing circuit 106 includes a filter processing circuit 105.
The image data output from the laser oscillator 1 is subjected to halftone processing using, for example, a sub-matrix, and then the laser oscillator 1
11 is a circuit for outputting a control signal.

The image processing CPU 107 is a circuit for centrally controlling the operations of the input processing circuit 101 to the multi-level dither circuit 106. This image processing CPU 10
In FIG. 7, correction data creating means 114 for creating color correction data for executing masking correction in the printer color correction circuit 102, and a correction coefficient for creating the color correction data corresponding to each color are set. The correction coefficient setting means 115 is provided. The correction coefficient set by the correction coefficient setting means 115 is stored in the storage means 11.
6 is input and stored.

The correction coefficient setting means 115, as shown in FIG. 4, reads H, L, S image data of C, M, Y obtained by reading an achromatic color sample described later in the scanner section 2. Color for obtaining the color vector of the color sample by converting the color data of the color system, that is, the data of the coordinate system representing the three attributes of the color consisting of hue (H), lightness (L) and saturation (S). Data conversion means 117
And a blending ratio setting unit 118 that sets the blending ratio of the toner so that the color vector becomes 0 based on the output data of the color data converting unit 117.

To set a correction coefficient for masking correction in the correction coefficient setting means 115, first, an equal amount of three primary color toners are mixed to form an achromatic color sample, and then this color sample is read by the scanner. In the part 2, the C, M, Y image data is read by the color data conversion means 117 and converted into color data of the H, L, S color system, so that in the hue-saturation plane system of the color sample. The color vector of the color sample is calculated.

That is, when the C, M, and Y toners do not contain impurities, as shown in FIG. 5, the color vector of each of the toners is H in the H, L, and S color coordinate system.
In the (hue) -S (saturation) plane, each 120 °
Therefore, the color belt of the color sample formed by mixing the color vectors of the toners is 0.
Should be.

However, when the hue of the toner of C is shifted toward the M side by the angle α as shown in FIG. 6 due to the inclusion of impurities in the toners, the color of the color sample is changed. The vector a will occur on the H (hue) -S (saturation) plane. Then, when it is confirmed that the color vector a is larger than the preset reference value β according to the output data of the color data conversion means 116, the toner ratio of C and Y is increased to increase the color vector. The blending ratio of each toner is set by the blending ratio setting means 118 so that a is set to 0, and the correction coefficient of each toner is set based on this blending ratio of the toner.

The color vector of the color sample formed by mixing the three primary color dyes composed of the C, M, and Y toners in the same amount is obtained, and the compounding ratio of each toner is set so that the color vector becomes zero. Since the correction coefficient for each toner is set based on this value, the correction coefficient for each toner can be calculated without complicated work such as determining how much color misregistration occurs for each toner. It can be set to an appropriate value.

Therefore, at the time of manufacturing the color image forming apparatus or at the time of periodic inspection, the correction coefficient is set and stored in the storage means 116, and the printer is operated based on the color correction data created according to the correction coefficient. Color correction circuit 10
2, masking correction can be properly performed.

For example, when an achromatic color is formed by mixing C, M, and Y toners, it is possible to prevent the formation of an inaccurate achromatic color due to the inclusion of impurities in each toner. By correcting the compounding ratio of each toner as described above, a desired achromatic color can be accurately formed. Also, when forming a chromatic image,
By performing masking correction in the printer color correction circuit 102 based on the correction coefficient, it is possible to prevent color misregistration due to mixing of the impurities and improve color reproducibility.

In the above embodiment, equal amounts of C, M and Y are used.
The example in which the image data of the color sample formed by mixing the three primary color toners made of toner is read by the reading unit including the scanner section 2 has been described. However, the image data of the three primary color toners is read by the scanner section 2 described above.
After individually reading the image data by the color data converting means 117 and converting the image data into color data of a color system based on the three attributes of color, a color vector in the hue-saturation plane system is obtained for each toner. The color data of the three primary color toners may be combined.

That is, as shown in FIG. 7, the correction coefficient setting means 115 may be provided with a synthetic vector computing means 119 for synthesizing the color data output from the color data converting means 117 to compute a synthetic vector. Good. Then, after the color data conversion means 117 finds the deviation amount and deviation direction of the color vector due to the mixing of impurities for each toner, the color vectors are combined to obtain the color vector α of the color sample shown in FIG. It may be configured such that a combined vector corresponding to is calculated.

According to this structure, since the color shift amount and the shift direction due to the mixing of impurities can be accurately obtained for each toner, the compounding ratio of each toner is set so that the above composite vector becomes zero. However, by setting the correction coefficient based on the set blending ratio of the toner, it is possible to effectively prevent color misregistration due to mixing of the above impurities and improve color reproducibility when forming an achromatic color. it can.

In the above embodiment, the case where the color misregistration caused by the impurities mixed in the toner is suppressed has been described. However, in order to prevent the color misregistration caused by the coloring of the recording paper, FIG. The correction coefficient setting means 115 shown in (1) may be used to set a correction coefficient for creating color correction data.

That is, by converting the color data of the recording paper read by the reading means such as the CCD of the scanner section 2 into the color data of the color system based on the three attributes of the color by the color data converting means 117, A color vector in the hue-saturation plane system of the recording paper is created, and based on the color vector of this color sample, the mixture ratio setting means 118.
The composition ratio of each toner may be set so that the color vector becomes 0, and the correction coefficient may be set based on the set composition ratio of the toner.

According to the above construction, for example, when an equal amount of three primary color toners is mixed on a reddish recording paper to form an achromatic color, it is reddish due to the influence of the color of the recording paper. Since the blending ratio of each toner is corrected so as to prevent the formation of an achromatic color, an accurate achromatic color can be formed on the recording paper.

In the above embodiment, an example in which the image data is read by the reading means such as the CCD of the scanner unit 2 provided in the color image forming apparatus 1 has been described, but the reading means is a separate unit. If the color data of the toner and the recording paper to be used is predetermined by a standard or the like,
A structure may be provided in which a reading unit that calculates the image data based on the data input from the input unit is provided.

The three primary color dyes used in the printer section 3 are not limited to toners, but may be inks or the like. Further, in the above embodiment, the case where the masking correction is performed on the three primary colors of the subtractive color mixture method including cyan (C), magenta (M) and yellow (Y) has been described, but the present invention is red (R) and green. It can also be applied to the case where the masking correction is performed on the three primary colors of the additive color mixture method of (G) and blue (B).

Further, although the color copying machine has been described as an example in the above embodiment, the present invention is not limited to this, and can be applied to a color image forming apparatus such as a color printer and a color facsimile. it can.

[0058]

As described above, according to the first aspect of the invention, the color vector of the color sample formed by mixing the equal amounts of the three primary color dyes is obtained, and this color vector is set to 0.
Since the composition ratio of each dye is set as described above and the correction coefficient for creating the color correction data is set based on this value, it is possible to determine the degree of color deviation for each dye. The correction coefficient can be set to an appropriate value without requiring complicated work.

Therefore, when the color image forming apparatus is manufactured or periodically inspected, the correction coefficient is set, and the masking correction is executed based on the color correction data created in accordance with the correction coefficient. When an achromatic color is formed by mixing C, M, and Y dyes, each dye is prevented from forming an inaccurate achromatic color due to the inclusion of impurities in each dye. There is an advantage that the blending ratio of is corrected and a desired achromatic color can be accurately formed.

According to the second aspect of the present invention, the image data of the three primary color dyes are individually read, and the image data is converted by the color data conversion means into color data of the color system based on the three attributes of the color, and the hue- After the color vector in the saturation plane system is calculated for each dye, the compounding ratio of each dye is set so that the combined vector obtained by combining the color data of the above three primary color dyes is set, and based on this value Since the correction coefficient is set according to the above, it is possible to accurately obtain the color shift amount and the shift direction mixed in the impurities for each dye.

Therefore, the correction coefficient can be appropriately set based on the compounding ratio of each of the dyes, and the color shift due to the inclusion of impurities in each dye can be effectively corrected based on the correction coefficient. The color reproducibility can be suppressed and the color reproducibility can be more effectively improved when an achromatic color is formed.

Further, according to the invention of claim 3, the color data of the recording paper read by the reading means is converted into the color data of the color system based on the three attributes of the color, whereby the hue-saturation of the color sample is converted. Create a color vector in the plane system,
Since the composition ratio of each dye is set so that the color vector of the recording paper is set to 0, and the correction coefficient for activating the color correction data is set based on the set composition ratio of the dye, the recording is performed. When an equal amount of three primary color dyes is mixed on the paper to form an achromatic color, there is an advantage that it is possible to prevent an incorrect achromatic color from being formed due to the influence of the color of the recording paper.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a color image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing an internal configuration of a color image forming apparatus.

FIG. 3 is a block diagram showing a configuration of an image processing unit.

FIG. 4 is a block diagram showing the structure of a correction coefficient setting means.

FIG. 5 is an explanatory diagram showing an H, L, S color coordinate system.

FIG. 6 is an explanatory diagram showing an H, L, S color coordinate system.

FIG. 7 is a view corresponding to FIG. 4, showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color image forming apparatus 2 Scanner section (reading means) 115 Correction coefficient setting means 117 Color data conversion means 118 Mixing ratio setting means 119 Composite vector calculation means

Claims (3)

[Claims] 1. A reading means for reading image data of a color sample formed by mixing equal amounts of the three primary color dyes in a color image forming apparatus for forming a color image by mixing the three primary color dyes, and the reading means. Color data conversion means for obtaining the color vector of the color sample in the hue-saturation plane system by converting the image data read by the means into the color data of the color system based on the three attributes of color, and this color data Based on the color vector of the color sample obtained by the conversion means, there is provided a mixture ratio setting means for setting the mixture ratio of each dye so that this color vector becomes 0, and the dye set by this mixture ratio setting means. A color image forming apparatus characterized in that a correction coefficient for creating color correction data is set in accordance with the mixture ratio of. 2. A color image forming apparatus for forming a color image by mixing three primary color dyes, a reading means for reading image data of the three primary color dyes, and the image data read by the reading means into three attributes of color. Based on the color data conversion means for converting the color data of the color system based on the color data, the color data of the three primary color dyes are combined based on the output data of the color data conversion means to obtain a composite vector of the three primary color dyes in the hue-saturation plane system. A combination vector calculation means for calculating and a combination ratio setting means for setting a combination ratio of each dye so as to make the combination vector zero based on the combination vector obtained by the combination vector calculation means are provided. According to the mixture ratio of the dye set by the ratio setting means, the correction coefficient for creating the color correction data is set. And a color image forming apparatus. 3. An image forming apparatus for forming a color image by transferring dyes of three primary colors onto a recording paper, and reading means for reading the color data of the recording paper, and color data of the recording paper read by the reading means. Color data conversion means for obtaining the color vector of the recording paper in the hue-saturation plane system by converting the color data of the color system based on the three attributes of color, and the recording obtained by the color data conversion means. Based on the color vector of the paper, there is provided a compounding ratio setting means for setting the compounding ratio of each dye so that this color vector becomes 0, and color correction is performed according to the compounding ratio of the dye set by this compounding ratio setting means. A color image forming apparatus configured to set a correction coefficient for data creation.