JPH10324026A - Image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming system in which color conversion parameters can be calculated and set while taking account of the phase direction as well as the chrominance and color conversion can be made closer visually to the color of a document. SOLUTION: A color patch generating section 13 outputs a fourth color image data corresponding to the three primary colors of an ink and the fourth color image data is delivered through a switch section 12 to a color image forming section 8. The color image forming section 8 forms the copy image of the fourth color image data which is then read out at a color image reading section 1 and a first color image data is outputted. A distance information extracting section 14 extracts the distance information in the color space at a corresponding pixel position based on the first and fourth color image data. A phase information extracting section 15 extracts the phase information in the color space at a corresponding pixel position based on the first and fourth color image data. A color conversion parameter calculating section 16 calculates color conversion parameters based on the distance and phase information and sets the color conversion parameters in a color converting section 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a digital color copying machine for reading a color image on a document and forming a duplicate image of the color image.

[0002]

2. Description of the Related Art The rapid development and spread of information devices such as personal computers have facilitated the processing of color images. Along with this, colorization has been progressing in the field of hard copy, which has been mainly monochrome images. The biggest problem with colorization in the field of hard copy is that the color image data inside the computer obtained by scanning the original with an image input means such as a scanner and the color obtained when the hard copy is made are reproduced with the correct colors. That is.

For this purpose, color image data inside a computer, generally R (red), G (green),
B (blue) and color image data by image forming means for actually performing hard copy, generally C (cyan), M
(Magenta), Y (yellow), K (black) or C, M, Y need to be color-converted so that they look visually identical.

As a typical method of the color conversion, a method using a masking equation is known. The masking equations use only the first-order terms of R, G, and B,
Some use the second-order terms.

[0005]

Conventionally, to determine the mask amount of the masking equation, a density difference least squares method for minimizing a color difference in a C, M, and Y color space of a color patch as a color sample has been used. Has been used. However, as can be seen from the low visual sensitivity to the change in the density of yellow, even if the color difference in the C, M, and Y color spaces other than the uniform color space is minimized, it cannot be converted to a visually correct color. It is thought that there is.

Further, visually, as represented by chromatic adaptation, when the color distribution in a color image changes in a constant phase direction in a color space, for example, in a lightness direction, it is easy to recognize the same color. Has characteristics.

Accordingly, the present invention provides an image forming apparatus capable of calculating and setting a color conversion parameter taking into account not only the color difference but also the phase direction, and capable of visually performing color conversion closer to the color of a document. The purpose is to:

[0008]

An image forming apparatus according to the present invention reads a color image of a document and outputs first color image data, and a first color image data output from the reading means. Converting color data into second color image data corresponding to a predetermined color component based on a preset color conversion parameter; and the predetermined color image data based on the second color image data output from the color conversion device. A first image forming unit that forms a color duplicated image on the image forming medium using the color component, and corresponding to the predetermined color component used for image formation by the first image forming unit;
A color sample generating means for generating third color image data serving as a color sample; and a third color image data output from the color sample generating means on the image forming medium by using the predetermined color component. A second image forming unit for forming a color duplicate image; and a pixel position corresponding to a first color image data output from the reading unit and a third color image data output from the color sample generating unit. A distance information extracting unit for extracting distance information in a color space; and a corresponding pixel position from the first color image data output from the reading unit and the third color image data output from the color sample generating unit. Phase information extracting means for extracting phase information in the color space of the color information, based on the distance information extracted by the distance information extracting means and the phase information extracted by the phase information extracting means. It is provided with a color conversion parameter calculating means for calculating the color conversion parameters used in the color conversion unit.

Further, the image forming apparatus of the present invention has a first reading means for reading a color image of a document and outputting first color image data, and a first color output from the first reading means. Color conversion means for converting image data into second color image data corresponding to a predetermined color component based on a preset color conversion parameter; and A first image forming unit that forms a color duplicate image on the image forming medium using a predetermined color component, and a first image forming unit that corresponds to the predetermined color component used for image formation by the first image forming unit;
A color sample generating means for generating third color image data serving as a color sample; and a third color image data output from the color sample generating means on the image forming medium by using the predetermined color component. Second image forming means for forming a color duplicate image, and second reading for reading the duplicate image on the image forming medium formed by the second image forming means and outputting first color image data Means for calculating a distance in a color space between data corresponding to the third color image data of the first color image data outputted from the second reading means and the third color image data. A distance information extracting unit that outputs the sum of all the image data as distance information, and a third color image data of the first color image data output from the second reading unit. Correspondingly A color misregistration vector which is a difference between the data and the third color image data in the color space is obtained, and an orthogonal projection of the obtained color misregistration vector in a predetermined phase direction is calculated. Phase information extraction means for outputting the sum of the phase information as phase information, and the distance information extracted by the distance information extraction means and the phase information extracted by the phase information extraction means used in the color conversion means based on the phase information A color conversion parameter calculating means for calculating a color conversion parameter.

In the image forming apparatus of the present invention, a reading means for reading a color image of a document and outputting first color image data, and the first color image data output from the reading means are set in advance. Color conversion means for converting the color component into second color image data corresponding to a predetermined color component based on the color conversion parameter, and using the predetermined color component based on the second color image data output from the color conversion means. A first image forming means for forming a color duplicate image on the image forming medium by using the first image forming means, and a third color sample corresponding to the predetermined color component used for image formation by the first image forming means. Color sample generation means for generating color image data;
A second image forming unit configured to form a color duplicate image on the image forming medium using the predetermined color component based on the third color image data output from the color sample generating unit; Based on color conversion parameters, distance information in a color space of a corresponding pixel position is extracted from first color image data output from the reading unit and third color image data output from the color sample generation unit. A distance information extracting unit, a first color image data output from the reading unit based on a color conversion parameter set in advance, and a third color image data output from the color sample generating unit. Phase information extracting means for extracting phase information in a color space, and color conversion parameters used in the distance information extracting means and the phase information extracting means Color conversion parameter calculating means for calculating the color conversion parameters used by the color conversion means based on the distance information extracted by the distance information extraction means and the phase information extracted by the phase information extraction means. Is provided.

Further, the image forming apparatus of the present invention has a first reading means for reading a color image of a document and outputting first color image data, and a first color output from the first reading means. Color conversion means for converting image data into second color image data corresponding to a predetermined color component based on a preset color conversion parameter; and A first image forming unit that forms a color duplicate image on the image forming medium using a predetermined color component, and a first image forming unit that corresponds to the predetermined color component used for image formation by the first image forming unit;
A color sample generating means for generating third color image data serving as a color sample; and a third color image data output from the color sample generating means on the image forming medium by using the predetermined color component. Second image forming means for forming a color duplicate image, and second reading for reading the duplicate image on the image forming medium formed by the second image forming means and outputting first color image data Means for color-converting the first color image data output from the second reading means in accordance with a color conversion parameter set in advance, and the third color of the color-converted first color image data Distance information extracting means for calculating the distance in the color space between the data corresponding to the image data and the third color image data and outputting the sum of all the image data as distance information; The first color image data output from the second reading means is color-converted according to a preset color conversion parameter, and the color-converted first color image data is converted to the third color image data. A color misregistration vector which is a difference between the corresponding data and the third color image data in the color space is obtained, and an angle between the obtained color misregistration vector and a predetermined phase direction is calculated. Phase information extraction means for outputting the sum of the data as phase information, and color conversion parameters used by the distance information extraction means and the phase information extraction means are set, and then extracted by the obtained distance information extraction means. Color conversion parameter calculation for calculating the color conversion parameter used by the color conversion means based on the distance information obtained and the phase information extracted by the phase information extraction means. It is and means.

In the image forming apparatus of the present invention, a reading means for reading a color image of a document and outputting first color image data, and the first color image data output from the reading means are set in advance. Color conversion means for converting into second color image data corresponding to a predetermined color component other than the black component based on the color conversion parameter, and extracting the black component from the second color image data output from the color conversion means A first processing unit that outputs the extracted black component as third color image data that has been separated, and the predetermined color component based on the third color image data that is output from the first processing unit. A first image forming unit for forming a color duplicate image on the image forming medium using the first image forming unit, and a color sample corresponding to the predetermined color component used for image formation by the first image forming unit. A color sample generating means for generating fourth color image data; and a color duplicate image on the image forming medium using the predetermined color component based on the fourth color image data output from the color sample generating means. A second image forming unit for forming a black component, and performing a reverse process of the process performed by the first processing unit on the fourth color image data output from the color sample generating unit to thereby convert the black component to another color image data. A second processing unit that distributes the color components and outputs the fifth color image data, and a first processing unit that is output from the reading unit.
Distance information extracting means for extracting distance information in a color space of a corresponding pixel position from the color image data of the second color image data and the fifth color image data output from the second processing means;
Phase information extracting means for extracting phase information in a color space of a corresponding pixel position from first color image data output from the reading means and fifth color image data output from the second processing means And a color conversion parameter calculation unit that calculates the color conversion parameter used by the color conversion unit based on the distance information extracted by the distance information extraction unit and the phase information extracted by the phase information extraction unit. I have.

Further, in the image forming apparatus of the present invention, reading means for reading a color image of a document and outputting first color image data, and first color image data output from the reading means are set in advance. Color conversion means for converting into second color image data corresponding to a predetermined color component other than the black component based on the color conversion parameter, and extracting the black component from the second color image data output from the color conversion means A first processing unit that outputs the extracted black component as third color image data that has been separated, and the predetermined color component based on the third color image data that is output from the first processing unit. A first image forming unit for forming a color duplicate image on the image forming medium by using the first image forming unit;
A color sample generating means for generating fourth color image data serving as a color sample corresponding to the predetermined color component used for image formation by the image forming means; and a fourth color output from the color sample generating means. A second image forming unit that forms a color duplicate image on the image forming medium using the predetermined color component based on the image data, and a fourth color image data output from the color sample generating unit. A second processing unit for distributing the black component to other color components by performing a reverse process of the process performed by the first processing unit and outputting the same as fifth color image data; Distance information in a color space of a corresponding pixel position from first color image data output from the reading unit and fifth color image data output from the second processing unit based on parameters; The distance information extracting means to be extracted corresponds to the first color image data output from the reading means and the fifth color image data output from the second processing means based on a preset color conversion parameter. Phase information extraction means for extracting phase information in the color space of the pixel position, and color conversion parameters used by the distance information extraction means and the phase information extraction means are set, and then extracted by the obtained distance information extraction means. Color conversion parameter calculation means for calculating the color conversion parameter used by the color conversion means based on the distance information and the phase information extracted by the phase information extraction means.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows the structure of an image forming apparatus such as a digital color copying machine for forming a duplicate image of a color image according to the present invention. In FIG. 1, a color image reading section 1 as a color image reading means is composed of, for example, an image scanner including a CCD type color line sensor and the like. , Object light R (red),
It is converted into electrical signals corresponding to the three primary colors of G (green) and B (blue) light, and 8-bit digital data for each pixel, that is, first color image data R,
G and B are output.

The first color image data R, G, B output from the color image reading unit 1 are sent to the phase-consideration type color conversion unit 2, respectively. As will be described in detail later, the phase-consideration type color conversion unit 2 is the most important part of the present invention, and converts input first color image data R, G, and B into a color image forming unit described later. 8 into color image data in a color space suitable for input.

The color image data output from the phase-consideration type color conversion unit 2 includes a color correction unit 3 for performing a color correction process, a scaling unit 4 for performing a scaling process, a spatial filter unit 5 for performing a spatial filtering process, and γ. The image data is sent to a color image forming unit 8 as an image forming unit via a γ conversion unit 6 for performing a conversion process and a halftone processing unit 7 for performing a halftone process.

The color image forming unit 8 includes yellow (Y), cyan (C), magenta (M), and black (K) color materials corresponding to third color image data Co, Mo, and Yo described later. Is attached to a sheet as a medium on which an image is to be formed, thereby forming a color image read by the color image reading unit 1 or a duplicate image corresponding to a color image of a color patch described later (hard copy). .

Here, as the color image forming section 8, for example, a so-called laser printer which forms an image using exposure scanning with a laser beam and an electrophotographic process is used.

Each of the units 1 to 8 operates under the control of the system control unit 10 in response to an input signal from an external interface (IF) 9.

FIG. 2 schematically shows the configuration of the phase-consideration type color converter 2 according to the first embodiment. Note that FIG.
Hereinafter, in order to simplify the description, the color correction unit 3, the scaling unit 4,
The spatial filter unit 5, the conversion unit 6, the halftone processing unit 7, the external interface 9, and the system control unit 10 are omitted.

In FIG. 2, first color image data R, G, B output from the color image reading unit 1 are sent to a color conversion unit 11 as color conversion means. The color conversion unit 11 converts the 8-bit R, G, and B first color image data input for each pixel into a color image by the color image forming unit 8 based on a preset color conversion parameter. The image data is converted into 8-bit second color image data C, M, and Y corresponding to the amounts of the color materials C (cyan), M (magenta), and Y (yellow), which are the three primary colors of the ink to be performed. Output.

The second color image data C, M, Y output from the color conversion section 11 are sent to the switch section 12, respectively. The switch unit 12 includes a second color image data output from the color conversion unit 11 and a color patch generation unit 13 described later.
The fourth color image data, which is the output of the second color image data, is input. If the switch state is "0", the second color image data is output. If the switch state is "1", the fourth color image data is output. 3, color image data Co, Mo,
This is output as Yo.

The third color image data Co, Mo, Yo output from the switch section 12 are sent to the color image forming section 8, respectively.

Color patch generator 1 as color sample generator
Reference numeral 3 denotes C, which are three primary colors of ink for forming a color sample as a color sample by the color image forming unit 8 for forming a color image.
The data is converted into fourth color image data Pc, Pm, and Py each of which is 8-bit data corresponding to the amounts of M and Y, and is output for each pixel.

The fourth color image data Pc, Pm, Py output from the color patch generation unit 13 are sent to the switch unit 12, respectively, and a distance information extraction unit 14 as a distance information extraction unit and a phase information extraction unit Is sent to the phase information extraction unit 15. Distance information extraction unit 14
Is the fourth color image data P for one screen of a color patch
The distance information in the color space of the corresponding pixel position is calculated and output from c, Pm, Py and the first color image data R, G, B of one screen sentence.

The phase information extracting section 15 outputs the corresponding pixel from the fourth color image data Pc, Pm, Py for one screen of the color patch and the first color image data R, G, B for one screen. It calculates and outputs the phase information of the position in the color space.

The distance information output from the distance information extractor 14 and the phase information output from the phase information extractor 15 are sent to a color conversion parameter calculator 16 as color conversion parameter calculator. The color conversion parameter calculation unit 16 calculates the distance information, which is output from the distance information extraction unit 14, and the phase information, which is output from the phase information extraction unit 15,
The color conversion parameters used in the color conversion unit 11 are calculated, and the calculated color conversion parameters are output to the color conversion unit 11.

Hereinafter, each part will be described in detail.

First, the color conversion parameter and color conversion unit 1
1 will be described with reference to FIG. The data of the three primary colors R, G, and B of the light obtained from the color image reading unit 1, that is, the first color image data R, G, and B are the data of the three primary colors of ink that control the amount of the color material for forming the color image A masking equation is used as a method of color correction processing for converting into C (cyan), M (magenta), and Y (yellow).
The basic formula is represented by the following equation (1).

[0031]

(Equation 1)

Here, C, M, and Y are electric signal amounts (referred to as electric signals C, M, and Y, respectively) of the respective color materials obtained as a result of the masking. R, G, and B are R, G, and B electric signal amounts obtained by color separation, and Ajk is a coefficient indicating a masking amount, which is a color conversion parameter. This number 1
The color conversion unit 11 as a masking circuit is configured based on the above, and an example thereof is a circuit shown in FIG.

In FIG. 3, first color image data R, G, and B are supplied to multipliers 21a, 21b, and 21c, respectively.
And are multiplied by the coefficients A11, A12, and A13, respectively. Next, the multiplication results of the multipliers 21a and 21b are respectively input to the adder 22a, and the two are added. Then, in the adder 22b, the multiplication result of the multiplier 21c and the addition result of the adder 22a are added, and the addition result is the second
Is output as color image data C.

Similarly, the first color image data R, G, and B input to the multipliers 21d, 21e, and 21f are multiplied by the coefficients A21, A22, and A23, respectively.
The multiplication results of d and 21e are added by the adder 22c, and the addition result and the multiplication result of the multiplier 21f are added to the adder 22d.
, And the second color image data M is output from the adder 22d.

Further, the first color image data R, G, B input to the multipliers 21g, 21h, 21i are multiplied by the coefficients A31, A32, A33, respectively.
g and 21h are added by an adder 22e, and the addition result and the multiplication result of the multiplier 21i are added to an adder 22f.
And the adder 22f outputs the second color image data Y.

Next, the switch section 12 will be described with reference to FIG. The switch unit 12 receives the second color image data and the fourth color image data, and converts the second or fourth color image data into the third color image data Co, Mo, Yo according to an input selection signal. As an example, the circuit shown in FIG.

In FIG. 4, the fourth color image data Pc and the second color image data C are input to the multiplexer 23a, and if the input selection signal is "1", the fourth color image data Pc is changed to "1". If 0 ", the second color image data C is output as the third color image data Co.

The multiplexer 23b receives the fourth color image data Pm and the second color image data M. If the input selection signal is "1", the fourth color image data Pm becomes "0". Then, the second color image data M
Is output as the third color image data Mo.

Similarly, the multiplexer 23c has the fourth
Is input, the fourth color image data Py is input if the input selection signal is "1", and the second color image data Y is input if the input selection signal is "0". 3 is output as color image data Yo.

That is, if the input selection signal is "1", the fourth color image data Pc, Pm, Py is obtained, and if the input selection signal is "0", the second color image data C, M, Y is output.
Are the third color image data Co, Mo, and Yo, respectively.
Is output as When setting color conversion parameters,
Since the input selection signal is set to “1”, the fourth color image data Pc, Pm, Py is output.

Next, the color image forming section 8 will be described. The color image forming section 8 has an undercolor removal UCR (Uncolored) for the purpose of reducing the amount of color material consumed when forming a color image.
derColor Removal) is used. To explain the principle simply, paying attention to the fact that when the same amount of each color material of cyan, magenta and yellow is mixed, black color, that is, black is obtained, the minimum amount of each color material is obtained, and it is calculated. This is the consumption of the color material black. That is, if the color image data corresponding to the black consumption is defined as k, it can be expressed by the following equation using the third color image data Co, Mo, and Yo.

K = MIN (Co, Mo, Yo) MIN: function for obtaining the minimum value As a result, the color image forming unit 8 actually consumes the cyan, magenta, yellow, and black color materials corresponding to the consumption amounts of the respective color materials. Among the five color image data c, m, y, and k, c, m, and y are represented by the following equations by removing a certain amount of black components obtained by the above equations.

C = Co-km = Mo-ky = Yo-k That is, by using the black (k) component, the amount of overlapping color materials is reduced and the consumption of each color material is reduced. Can be expected.

The color image data Co, Mo,
FIG. 5 shows a specific example of a circuit for performing a UCR process for removing a certain amount of black component from Yo and reducing each signal amount.

In FIG. 5, the color image data Co and M
The value o is compared by the comparator 24a for the magnitude of the value, and the resulting signal (for example, 0 if the data Co is small)
Is output to the selector 25a.

Color image data Co and Mo are input to input ports P0 and P1 of the selector 25a, respectively.
An input port (for example, input port P0 if the control signal is 0) is selected by a control signal (for example, 0 if data Co is small) from comparator 24a, and that signal is output. This output signal OUTP becomes OUTP = MIN (Co, Mo).

Similarly, the signal OUT is supplied to the comparator 24b.
P and color image data Yo, a control signal of the comparison result is input to a selector 25b, and a signal OUTP
And the color image data Yo to the input ports P2 and P3 of the selector 25b, respectively, so that the output signal O
UTK becomes OUTK = MIN (Co, Mo, Yo), and the fifth color image data k which is a digital signal of the black component amount is obtained.

Further, the color image data Co and the signal OU
The TK is input to the subtractor 26a, and the subtraction of subtracting the signal OUTK from the color image data Co yields fifth color image data c. Similarly, the signal OUTK is subtracted from the color image data Mo by the subtractor 26b, and the fifth color image data m is obtained by the subtractor 26c.
The signal OUTK is subtracted from o to obtain fifth color image data y.

The color image forming section 8 uses the amounts of cyan, magenta, yellow, and black color materials corresponding to the fifth color image data c, m, y, and k obtained in this manner to color each unit pixel. Form an image.

Next, the color patch generator 13 will be described with reference to FIG. As shown in Table 1 below, a plurality of color patch data are prepared as color image data Pc, Pm, and Py, each of which is 8-bit data corresponding to three primary colors of ink, and a subscript i in the table is used as an address. RO
M (read only memory) 31. Hereinafter, when clearly indicating that the data is the i-th color patch data, i is represented as a subscript such as Pci, Pmi, Pyi, and the like, and other color image data corresponding thereto, for example, R, G, and B, are also represented. A similar notation is used.

[0051]

[Table 1]

The counter 32 counts the main scanning image clock, and the counter 33 counts the sub scanning image clock. These two count values are output to the address decoder 34. In the address decoder 34,
The address of the ROM 31 where the color patch data corresponding to the pixel positions of these two count values is stored is selected.

The R selected by the address decoder 34
From the address of OM31, the color patch data Pc, Pm, P
y is read and latched by the latch 35. Latch 35
Output color patch data Pc, Pm, and Py. FIG. 12 shows the color image data of the color patches for one screen outputted at this time, and (10, 10, 10), (2) in FIG.
(0, 20, 20), (40, 40, 40), (50, 50, 50) show examples of specific density values of the color patch data Pci, Pmi, Pyi.

Next, the distance information extracting unit 14 will be described with reference to FIG. In FIG. 7, a counter 41 counts a main scanning image clock, and a counter 42 counts a sub scanning image clock. These two counters 4
In addition to the main scanning position and the sub-scanning position indicated by reference numerals 1 and 42, the first color image data R, G,
B and the information memory 4 in which the fourth color image data Pc, Pm and Py from the color patch generation unit 13 are constituted by a dual port RAM (random access memory).
3

The main controller 44 comprises an MPU (microprocessor unit) and its peripheral circuits, and operates according to a program stored in a program memory 45 such as an EEPROM.

The distance information memory 46 has a dual port R
The main control unit 44 is configured by the main control unit 44 based on the data stored in the information memory 43.
5 in the color space corresponding to one screen of the color patch data processed by the distance information extracting program (Pci, P
mi, Pyi) and (Ri, Gi, Bi). The distance information stored in the distance information memory 46 is output to the color conversion parameter calculator 16.

The information memory 43, the program memory 45, and the distance information memory 46 are provided with a data bus 47, respectively.
Is connected to the main controller 44.

Next, the phase information extracting section 15 will be described with reference to FIG. In FIG. 8, a counter 51 counts a main scanning image clock, and a counter 52 counts a sub scanning image clock. These two counters 5
Along with the main scanning position and the sub-scanning position indicated by 1, 52, the first color image data R, G,
B and the fourth color image data Pc, Pm, Py from the color patch generator 13 are stored in the information memory 53 composed of a dual port RAM.

The main control section 54 is composed of an MPU and its peripheral circuits, and operates according to a program stored in a program memory 55 composed of an EEPROM or the like.

The phase information memory 56 has a dual port R
The main control unit 54 is constituted by an AM and stores the program memory 5 based on the data stored in the information memory 53.
5, (Pci, Pci) in the color space corresponding to one screen of the color patch data processed by the phase information extraction program in FIG.
mi, Pyi) and (Ri, Gi, Bi). The phase information stored in the phase information memory 56 is output to the color conversion parameter calculator 16.

The information memory 53, the program memory 55, and the distance information memory 56 are each provided with a data bus 57.
Is connected to the main control unit 54.

Next, the color conversion parameter calculator 16 will be described with reference to FIG. In FIG. 9, the distance information from the distance information extraction unit 14 and the phase information extraction unit 1 are stored in an information memory 61 composed of a dual port RAM.
5 is stored. The main control unit 62
U and its peripheral circuits,
It operates according to the program stored in the program memory 63 constituted by

The color conversion parameter memory 64 has an EEPR
The main control unit 62 is configured by the OM based on data stored in the information memory 61.
Is a memory for storing color conversion parameters processed by the color conversion parameter calculation program. Selector 65
Is controlled by the main control unit 62 to perform input / output selection control for the color conversion parameter memory 64.

The information memory 61, the program memory 63, and the selector 65 are connected to the main control unit 62 by a data bus 66, respectively.

After calculating the color conversion parameters, the main control unit 62 controls the selector 65 to transfer the color conversion parameters to the color conversion parameter memory 64. After the transfer, the color conversion parameters are transferred from the color conversion parameter memory 64 to the color conversion unit 11. The selector 65 is controlled to output a parameter.

As is apparent from the above configuration, the main control unit, program memory, data bus, and the like of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 can be shared. That is, needless to say.

Next, the operation of the above configuration will be described.

First, the general operation processing will be described with reference to the flowchart shown in FIG. In the present image forming apparatus, roughly two types of operation processing can be selected on a control panel (not shown). That is, when a color conversion parameter switch is turned on in a control panel (not shown) (S41), a color conversion parameter setting mode is set, and an operation process for setting a color conversion parameter, which will be described later, is performed (S42). (S41), a normal image forming operation described later is performed (S43). When this image forming apparatus is used for the first time, first, the operation processing of the color conversion parameter setting is performed, and then,
A normal image forming operation is performed.

Next, the operation of setting the color conversion parameters will be described with reference to the flowchart shown in FIG. In the first embodiment, a color conversion parameter is determined from color patch data and a copy of the color patch data and read color image data. After that, read the color image on the original,
When forming a duplicate image of the color image, a processing operation using the determined color conversion parameters is performed.

First, the color patch generation unit 13 outputs
Outputs fourth color image data Pc, Pm, and Py each being 8-bit data corresponding to the primary color (S1);
The information is sent to the switch unit 12, the distance information extraction unit 14, and the phase information extraction unit 15, respectively. FIG. 10 shows an example of color image data of a color patch for one screen output from the color patch generation unit 13 at this time.

At the time of setting the color conversion parameters, the input selection signal is set to "1", so that the switch section 12 selects the fourth color image data Pc, Pm, Py (color patch data) and sets the third color image data. Output as image data Co, Mo, Yo (S2).

Next, in the color image forming section 8, a duplicate image of one screen of the fourth color image data Co, Mo, Yo is formed (S3). In this case, the input selection signal of the switch unit 12 is “1”, and the fourth color image data Pc,
Since Pm and Py are selected, an image of one screen of the fourth color image data Pc, Pm, and Py is actually copied, and an example of the copied image is shown in FIG.
become that way. (F0, F0, F0), (E0, E0, E
0), (C0, C0, C0), (A4, A4, A4) show examples of specific density values of the output color image data Ri, Gi, Bi.

Next, a duplicate image of the color patch data Pc, Pm, Py duplicated by the color image forming section 8 (FIG. 1)
3) is read by the color image reading unit 1 (S
4). The color image reading section 1 outputs first color image data R, G, B, which is read color data.

The first color image data R, G, B output from the color image reading section 1 are sent to the distance information extracting section 14 and the phase information extracting section 15, respectively. The fourth color image data Pc, Pm, and Py from the color patch generation unit 13 are also input to the distance information extraction unit 14. The first color image data R, G, B input at this time are:
In step S3, the fourth color image data Pc,
Pm and Py are copied in the color image forming section 8, and the process proceeds to step S
4, the image is read by the color image reading unit 1.

The distance information extracting section 14 is configured to output the first color image data R, G, B and the fourth color image data Pc,
(Pci, Pmi, Pyi) and (Ri, G) in a color space corresponding to one screen of color patch data based on Pm and Py.
The distance information of (i, Bi) is extracted (S5) and output to the color conversion parameter calculation unit 16.

The phase information extracting unit 15 receives the fourth color image data Pc, Pm, and Py from the color patch generating unit 13 as well as the first color image data R, G, and B. At step S3, the first color image data R, G, and B input at this time are copied from the fourth color image data Pc, Pm, and Py by the color image forming unit 8, and at step S4, the color image is read. It is read by the unit 1.

The phase information extracting section 15 is provided with first color image data R, G, B and fourth color image data Pc,
(Pci, Pmi, Pyi) and (Ri, G) in a color space corresponding to one screen of color patch data based on Pm and Py.
The phase information of (i, Bi) is extracted (S6) and output to the color conversion parameter calculation unit 16.

The color conversion parameter calculator 16 calculates the distance information from the distance information extractor 14 and the phase information extractor 1
Calculate the color conversion parameter based on the phase information from 5,
Output to the color conversion unit 11 (S7). In the color conversion unit 11,
The color conversion parameter output from the color conversion parameter calculator 16 is set as the masking amount Ajk of the circuit in FIG. 3 (S8).

The above is the flow of the operation processing at the time of setting the color conversion parameters in the first embodiment.

After setting the color conversion parameters in this manner, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG. That is, first, the color image of the document is read by the color image reading unit 1, and the first color image data R, G, B are output (S21).

The first color image data R, G, B output from the color image reading unit 1 is sent to the color conversion unit 11,
Based on the previously set color conversion parameters, the image data is converted into second color image data C, M, and Y corresponding to the amounts of cyan, magenta, and yellow color materials (S22).

In the second color image data C, M, and Y output from the color conversion section 11, the input selection signal of the switch section 12 is "0" at this time, and the second color image data is selected. Therefore, the image data is sent to the color image forming unit 8 via the switch unit 12 (S23). The color image forming unit 8
A duplicate image for one screen of the second color image data C, M, Y is created (S24).

Next, a second embodiment will be described.

In the second embodiment, the masking amount Ajk (1 <j, k <
The color conversion parameter is calculated for the purpose of determining 3) such that the evaluation function E expressed by the following equations 2 to 5 is minimized in the color space.

[0085]

(Equation 2)

[0086]

(Equation 3)

[0087]

(Equation 4)

[0088]

(Equation 5)

Here, α1 and α2 are appropriate positive numbers,
s, t, and u are appropriate unit vectors in the C, M, and Y color spaces. E1 is Ci, Mi, in the C, M, Y color space.
Y2 represents the sum of the distances between Pci, Pmi, and Pyi, and E2 is (Ci-Pci, Mi-Pmi, Yi-P
yi) is obtained by adding a negative sign to the sum of squares of the lengths of orthogonally projected lengths of the vector yi) in the unit vector (s, t, u) direction. The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the (s, t, u) direction. be able to.

The configuration of the phase-consideration type color conversion unit 2 in the present embodiment is the same as that of the first embodiment described above with reference to FIG.
Although the description is omitted because it is the same as that described above, the operation process of the color conversion parameter setting will be described with reference to the flowchart shown in FIG. The same parts as those in FIG. 11 described in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described. That is, the operation processing of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 will be described.

Color conversion parameter A for minimizing Equation 2
jk is obtained by the following equation (6).

[0092]

(Equation 6)

That is, the distance information is obtained from the term relating to E1 in the above equation (6), and the phase information is obtained from the term relating to E2 in the above equation (6).

First, the operation of the distance information extracting unit 6 will be described. The term relating to E1 in the above equation (6) is expressed by the following fourth color image data Pci, Pmi, Pyi, the first color image data Ri, Gi, Bi read by copying and reading the color data, and the color conversion parameter Ajk. Expressions 7 and 8 are used.

[0095]

(Equation 7)

However,

(Equation 8)

That is, the above equation (7) is summarized as the following equation (9), and becomes a linear expression of the color conversion parameter.
ln, f1jk are the fourth color image data Pci, Pm
From i, Pyi and the first color image data Ri, Gi, Bi read by duplicating them, the calculation is performed by multiplication and addition of the above equation (7).

[0098]

(Equation 9)

The distance information extraction unit 14 performs the processing in step S9 in the flowchart of FIG.
jkln (1 <j <3, 1 <k <3, 1 <l <3, 1 <
n <3) and f1jk (1 <j <3, 1 <k <3) are calculated by the main control unit 44 in accordance with the program obtained by programming Equation 7 in the program memory 45, and are stored in the distance information memory 46. After storing, it is output to the color conversion parameter calculation unit 16.

As is clear from the calculation of the above equation (7), d1
jkln (1 <j <3, 1 <k <3, 1 <l <3, 1 <
By using a circuit configuration in which a multiplier and an adder are combined for the calculation of n <3) and f1jk (1 <j <3, 1 <k <3), the speed of the calculation can be increased. A specific circuit diagram is omitted.

Next, the operation of the phase information extracting unit 15 will be described. The term relating to E2 in the equation (6) is the fourth color image data Pci, Pmi, Pyi, and the first color image data Ri, Gi, Bi read by duplicating them.
The color conversion parameter Ajk is used to calculate the color conversion parameter A.
jk as a linear expression. As an example, E in A11
The following equation (10) shows the case where 2 is partially differentiated.

[0102]

(Equation 10)

That is, the above equation (10) is summarized by the following equation (11) including the case other than A11, and becomes a linear expression of the color conversion parameter. D2jkln and f2jk are the fourth color image data Pci, Pmi, Pyi and It is calculated from the first color image data Ri, Gi, Bi read by duplicating this and multiplying and adding the above equation (7).

[0104]

[Equation 11]

The phase information extraction unit 15 performs the processing in step S10 in the flowchart of FIG.
2jkln (1 <j <3, 1 <k <3, 1 <l <3, 1
<N <3), f2jk (1 <j <3, 1 <k <3)
The main control unit 54 calculates according to a program in which the above equation (10) or the like in the program memory 55 is programmed, stores it in the phase information memory 56, and outputs it to the color conversion parameter calculation unit 16.

As is clear from the calculation of the above equation (10), d
2jkln (1 <j <3, 1 <k <3, 1 <l <3, 1
<N <3) and f2jk (1 <j <3, 1 <k <3) can be operated at high speed by using a circuit configuration combining a multiplier and an adder. . A specific circuit diagram is omitted.

Next, the operation of the color conversion parameter calculator 16 will be described. In the color conversion parameter calculation unit 16,
The color conversion parameter Ajk is calculated by the equation (6).

In the information memory 61, the distance information d1jkln, f1jk (1 <j, k, l,
n <3) and the phase information d2jkln, f2jk (1 <j, k,
1, n <3) are input.

From Equations 9 and 11, Equation 6 is expressed as a simultaneous equation of color conversion parameters Ajk as shown in Equation 12 below.

[0110]

(Equation 12)

The color conversion parameter calculation unit 16 determines that d1jkln, f1jk, d2 in the information memory 61 in step S11 in the flowchart of FIG.
The main control unit 62 executes a program in the program memory 63 for constructing a simultaneous linear equation relating to Ajk of the above formula 12 from jkln and f2jk and calculating a color conversion parameter Ajk by LU decomposition.

The color conversion parameter Ajk calculated by the main controller 62 is stored in the color conversion parameter memory 64 via the selector 65. As shown in the flowchart of FIG. 15, the color conversion parameter Ajk stored in the color conversion parameter memory 64 is sent again to the color conversion unit 11 via the selector 65 and is set (S8).

The above is the flow of the operation processing at the time of setting the color conversion parameters in the second embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, a third embodiment will be described.

In the third embodiment, the masking amount Ajk (1 <j, k <
The color conversion parameter is calculated for the purpose of determining 3) such that the evaluation function E expressed by the following Expressions 13 to 17 is minimized in the color space.

[0117]

(Equation 13)

[0118]

[Equation 14]

[0119]

(Equation 15)

[0120]

(Equation 16)

[0121]

[Equation 17]

Note that α1 and α2 are appropriate positive numbers.
E1 is Ci, Mi, Yi and Pc in the C, M, Y color space.
represents the sum of the distances of i, Pmi, and Pyi, and E2
Is obtained by adding a negative sign to the sum of the squares of the squares of orthogonally projected color shift vectors (Ci-Pci, Mi-Pmi, Yi-Pyi) onto the average vector of the color shift vectors.
The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the direction of the average value of the color shift vector. Can be.

Color conversion parameter A for minimizing Equation 2
jk is obtained by the following equation (18).

[0124]

(Equation 18)

Although the details are omitted here,

[Equation 19]

[0126]

(Equation 20)

D1jkln, f1jk, d2ikl
n, f2jk (1 <j, k, l, n <3) are Pci, P
It can be calculated from mi, Pyi, Ri, Gi, and Bi. Therefore, the above equation (18) becomes a simultaneous linear equation relating to Ajk in the above equation (12), and Ajk is calculated by the same processing as in the above-described second embodiment.

The configuration of the phase-consideration type color converter 2 according to the present embodiment is similar to that of the first embodiment described above with reference to FIG.
Therefore, the description is omitted. The operation process of the color conversion parameter setting is as shown in the flowchart of FIG. 16, and is substantially the same as that of FIG. 15 described in the second embodiment. Steps S12 and S1 in FIG.
Steps S3 and S14 correspond to steps S9, S10 and S11 in FIG.

Next, a fourth embodiment will be described.

FIG. 17 schematically shows the configuration of the phase-consideration type color converter 2 according to the fourth embodiment. In the fourth embodiment, an initial value of the color conversion parameter Ajk is output from the color conversion parameter calculation unit 16 to the distance information extraction unit 14 and the phase information extraction unit 15, and the distance information extraction unit 1
4 and the phase information extraction unit 15, the color conversion parameter A
The second embodiment is different from the first embodiment in that an initial value of jk is also used, and the rest is the same as the first embodiment.
Therefore, the same portions as those of the first embodiment (FIG. 2) are denoted by the same reference numerals, and description thereof will be omitted. Only different portions will be described.

The distance information extracting section 14 will be described with reference to FIG. In FIG. 18, a counter 41 counts a main scanning image clock, and a counter 42 counts a sub scanning image clock. These two counters 41,
Along with the main scanning position and the sub-scanning position indicated by reference numeral 42, the first color image data R, G, B,
Further, the fourth color image data Pc, Pm, Py from the color patch generator 13 is stored in the information memory 43.

The color conversion parameter memory 48 has an EEPR
The color conversion parameters which are configured by the OM and output from the color conversion parameter calculation unit 16 are stored. The main control unit 44 operates according to a program stored in the program memory 45.

The distance information memory 46 is processed by the main control unit 44 according to the distance information extraction program in the program memory 45 based on the data stored in the information memory 43 and the color conversion parameters stored in the color conversion parameter memory 48. (Pci, Pmi, Pyi) and (Ri, Gi, B) in a color space corresponding to one screen of
This is a memory for storing the distance information of i). The distance information stored in the distance information memory 46 is output to the color conversion parameter calculator 16.

These information memory 43, program memory 45, distance information memory 46, color conversion parameter memory 4
8 are connected to the main control unit 44 by a data bus 47, respectively.

Next, the phase information extracting unit 15 shown in FIG.
This will be described with reference to FIG. In FIG. 19, a counter 51 counts a main scanning image clock, and a counter 52 counts a sub scanning image clock. Together with the main scanning position and the sub-scanning position indicated by these two counters 51 and 52, the first color image data R,
G, B, and the fourth color image data Pc, Pm, Py from the color patch generation unit 13 are stored in the information memory 53.

The color conversion parameter memory 58 has an EEPR
The color conversion parameters which are configured by the OM and output from the color conversion parameter calculation unit 16 are stored. The main controller 54 operates according to a program stored in the program memory 55.

The phase information memory 56 is processed by the main control unit 54 by the phase information extraction program in the program memory 55 based on the data stored in the information memory 53 and the color conversion parameters stored in the color conversion parameter memory 58. (Pci, Pmi, Pyi) and (Ri, Gi, B) in a color space corresponding to one screen of
This is a memory for storing the phase information of i). The phase information stored in the phase information memory 56 is output to the color conversion parameter calculator 16.

These information memory 53, program memory 55, distance information memory 56, color conversion parameter memory 5
8 are connected to the main control unit 54 by a data bus 57, respectively.

Next, the color conversion parameter calculator 16 will be described with reference to FIG. In FIG. 20, the information memory 61 stores distance information from the distance information extracting unit 14 and phase information from the phase information extracting unit 15. The main controller 62 operates according to a program stored in the program memory 63.

The main control section 62 executes a color conversion parameter quality judgment program in the program memory 63 based on the distance information and the phase information in the information memory 61. If the result of the color conversion parameter pass / fail determination is “good”, the main control unit 6
2 controls the selector 65 so as to output the color conversion parameters in the color conversion parameter memory 64 to the color conversion unit 11. If the result of the color conversion parameter pass / fail determination is “No”, the main control unit 62 executes the color conversion parameter calculation program in the program memory 63 to calculate the color conversion parameters, and stores them in the color conversion parameter memory 64. I do.
After the storage, the color conversion parameters in the color conversion parameter memory 64 are stored in the distance information extraction unit 14 and the phase information extraction unit 15
Sent to

After calculating the color conversion parameters, the main control unit 62 controls the selector 65 to transfer the color conversion parameters to the color conversion parameter memory 64. After the transfer, the color conversion from the color conversion parameter memory 64 to the color conversion unit 11 is performed. The selector 65 is controlled to output a parameter.

Next, the operation of the above configuration will be described.

First, the operation of setting the color conversion parameters will be described with reference to the flowchart shown in FIG. Note that FIG. 11 described in the first embodiment described above.
The same reference numerals are used to denote the same parts, and detailed description is omitted.
The different parts will be described in detail.

First, the color patch generator 13 outputs the fourth color image data Pc, Pm, Py (S1), and sends them to the switch 12, the distance information extractor 14, and the phase information extractor 15, respectively. . At the time of setting the color conversion parameters, the input selection signal is set to "1".
Selects the fourth color image data Pc, Pm, Py (color patch data), and selects the third color image data Co, M
Output as o and Yo (S2).

Next, in the color image forming section 8, a duplicate image of one screen of the fourth color image data Co, Mo, Yo is formed (S3). Next, the color image reading unit 1 reads a duplicate image of the color patch data Pc, Pm, and Py duplicated by the color image forming unit 8, and outputs first color image data R, G, and B (S4). The first color image data R, output from the color image reading unit 1,
G and B are the distance information extraction unit 14 and the phase information extraction unit 1
5 respectively.

On the other hand, from the color conversion parameter calculating section 16,
The initial value of the color conversion parameter Ajk is output to the distance information extraction unit 14 and the phase information extraction unit 15, and is set (S15). That is, the initial value of the color conversion parameter Ajk stored in advance in the color conversion parameter memory 64 is sent to the distance information extraction unit 14 and the phase information extraction unit 15 by the operation of the selector 65 under the control of the main control unit 62. Each is set.

The fourth color image data Pc, Pm, and Py from the color patch generator 13 are also input to the distance information extractor 14. In step S3, the first color image data R, G, and B input at this time are converted into the fourth color image data Pc, Pm, and Py by the color image forming unit 8.
And in step S4, the color image reading unit 1
Has been read.

The distance information extracting unit 14 is configured to output the first color image data R, G, B and the fourth color image data Pc,
Based on the initial values of Pm, Py and the color conversion parameter Ajk, distance information of (Pci, Pmi, Pyi) and (Ri, Gi, Bi) in a color space corresponding to one screen of color patch data is extracted. (S16) Output to the color conversion parameter calculation unit 16.

The phase information extracting unit 15 receives the fourth color image data Pc, Pm, and Py from the color patch generating unit 13 as well as the first color image data R, G, and B. At step S3, the first color image data R, G, and B input at this time are copied from the fourth color image data Pc, Pm, and Py by the color image forming unit 8, and at step S4, the color image is read. It is read by the unit 1.

The phase information extracting section 15 is provided with first color image data R, G, B and fourth color image data Pc,
Based on the initial values of Pm, Py and the color conversion parameter Ajk, phase information of (Pci, Pmi, Pyi) and (Ri, Gi, Bi) in a color space corresponding to one screen of color patch data is extracted. (S17), and output to the color conversion parameter calculation unit 16.

The color conversion parameter calculator 16 calculates the distance information from the distance information extractor 14 and the phase information extractor 1
Based on the phase information from Step 5, a color conversion parameter pass / fail judgment program is executed (S18). If the result of the color conversion parameter pass / fail determination is “good”, the color conversion parameters in the color conversion parameter memory 64 are output to the color conversion unit 11 and set (S8).

If the result of the color conversion parameter pass / fail judgment is “No”, the color conversion parameter calculation program is executed to calculate the color conversion parameters, and the color conversion parameters are stored in the color conversion parameter memory 64 (S19). After the storage, the color conversion parameters in the color conversion parameter memory 64 are sent to the distance information extraction unit 14 and the phase information extraction unit 15, and again
The operations of steps S16 to S18 are repeated.

The above is the flow of the operation processing when setting the color conversion parameters in the fourth embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, a fifth embodiment will be described.

In the fifth embodiment, the masking amount Ajk (1 <j, k <
The color conversion parameter is calculated for the purpose of determining 3) such that the evaluation function E expressed by the following equations 21 to 25 is minimized in the color space.

[0157]

(Equation 21)

[0158]

(Equation 22)

[0159]

(Equation 23)

[0160]

(Equation 24)

[0161]

(Equation 25)

Here, α1 and α2 are appropriate positive numbers,
s, t, and u are appropriate unit vectors in the C, M, and Y color spaces. E1 is Ci, Mi, in the C, M, Y color space.
Represents the sum of squares of the distances between Yi and Pci, Pmi, Pyi, and E2 is (Ci-Pci, Mi-Pmi, Yi
−Pyi) and a unit vector (s,
t, u) (0 ≦ θi ≦ π / 2). The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the (s, t, u) direction. be able to.

The configuration of the phase-consideration type color conversion section 2 in the present embodiment is the same as that of FIG. 1 described in the fourth embodiment.
Although the description is omitted because it is the same as that of FIG. 7, the operation process of the color conversion parameter setting will be described with reference to the flowchart of FIG. 21 described in the fourth embodiment. The description of the same parts as those in the fourth embodiment will be omitted, and only different parts will be described. That is, the operation processing of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 will be described.

In step S16, the distance information extraction unit 14 calculates Eq. 23 and outputs E1 as distance information. In step S17, the phase information extraction unit 15 calculates Eq. 24 and outputs E2 as distance information.

In step S18, the color conversion parameter calculating section 16 evaluates the distance information and the phase information obtained as described above by calculating the above equation (22). If the evaluation value E is equal to or less than a predetermined allowable value, the color conversion parameter Ajk at this time is output to the color conversion unit 11 (S8). If the evaluation value E is larger than the allowable value, the color conversion parameter is updated. (S19).

The process of updating the color conversion parameters in step S19 will be described with reference to the flowchart shown in FIG. First, the operation of the color conversion parameter calculation unit 16 in step S31 will be described. The color conversion parameter increment ajk (1 <j, k <3) is stored in the information memory 61 in advance. Each color conversion parameter Ajk
Is added to “0” or ajk or −ajk. There are a total of 19683 ways of changing the color conversion parameters. One of these combinations (for example, only A11 has a
11 is added and other color conversion parameters are not changed), and the changed color conversion parameter Ajk is output to the distance information extracting unit 14 and the phase information extracting unit 15.

Next, the operation of the distance information extraction unit 14 in step S32 will be described. The distance information extraction unit 14 calculates Eq. 23 using the color conversion parameter Ajk newly output from the color conversion parameter calculation unit 16 and outputs E1 as distance information.

Next, the operation of the phase information extraction unit 15 in step S33 will be described. The phase information extraction unit 15 calculates Eq. 24 using the color conversion parameter Ajk newly output from the color conversion parameter calculation unit 16 and outputs E2 as phase information.

Next, in step S34, the color conversion parameter calculation section 16 calculates the evaluation value of the above equation (22) using the evaluation values E1 and E2.
jk and the evaluation values E1 and E2 are stored in the information memory 61.

By adding "0" or ajk or -ajk to each color conversion parameter Ajk, the processing of steps S31 to S34 is repeated for all combinations of the obtained color conversion parameters.

After the end of the repetition, the operation of the color conversion parameter calculation section 16 in step S35 will be described. The information memory 61 stores the evaluation values E1, E2, E and the color conversion parameters Ajk corresponding to the evaluation values. The main control unit 62 selects the color conversion parameter Ajk that minimizes the evaluation value E from the evaluation values E stored in the information memory 61 by the color conversion parameter update program in the program memory 63.

The main control section 62 transfers the selected color conversion parameter to the color conversion parameter memory 64 and stores it. After the storage, the main control unit 62 controls the selector 65 so that the color conversion parameters can be output from the color conversion parameter memory 64 to the distance information extraction unit 14 and the phase information extraction unit 15. With the above processing, the update processing of the color conversion parameter Ajk in step S19 ends.

Following the update, in step S16, the distance information extracting unit 14 calculates distance information in the case of the updated color conversion parameter Ajk, and outputs the distance information to the color conversion parameter calculating unit 16. In step S17, the phase information extraction unit 15 calculates the phase information for the updated color conversion parameter Ajk, and outputs the phase information to the color conversion parameter calculation unit 16.

In step S18, the color conversion parameter calculating section 16 evaluates again by calculating the expression 22 using the distance information and the phase information obtained in steps S16 and S17. If the evaluation value E is equal to or less than a predetermined allowable value, or if the evaluation value E does not decrease any more (the evaluation value does not change even if the update operation is performed), the color conversion parameter Is completed, the color conversion parameter Ajk is output from the color conversion parameter memory 64 to the color conversion unit 11, and is set as a mask amount (S8).

The above is the flow of the operation processing for setting the color conversion parameters in the fifth embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, a sixth embodiment will be described.

In the sixth embodiment, the masking amount Ajk (1 <j, k <
In order to determine 3) in the color space such that the evaluation function E represented by the following equations 26 to 31 is minimized, a color conversion parameter is calculated.

[0179]

(Equation 26)

[0180]

[Equation 27]

[0181]

[Equation 28]

[0182]

(Equation 29)

[0183]

[Equation 30]

[0184]

(Equation 31)

Here, α1 and α2 are appropriate positive numbers,
E1 is Ci, Mi, Yi and Pc in the C, M, Y color space.
represents the sum of squares of the distances of i, Pmi, Pyi,
E2 is (Ci-Pci, Mi-Pmi, Yi-Pyi)
This is the sum of the phase differences (0 ≦ ψi ≦ π / 2) between the color shift vector and the average vector of the color shift vectors. The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the direction of the average value of the color shift vector. Can be.

The configuration of the phase-consideration type color conversion section 2 in the present embodiment is the same as that of the fourth embodiment described with reference to FIG.
Although the description is omitted because it is the same as that of FIG. 7, the operation process of the color conversion parameter setting will be described with reference to the flowchart of FIG. 21 described in the fourth embodiment. The description of the same parts as those in the fourth embodiment will be omitted, and only different parts will be described. That is, the operation processing of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 will be described.

In step S16, the distance information extracting unit 14 calculates Eq. 28 and outputs E1 as distance information. In step S17, the phase information extraction unit 15 calculates Eq. 29 and outputs E2 as distance information.

In step S18, the color conversion parameter calculating section 16 evaluates the distance information and the phase information obtained as described above, by calculating the expression (27). If the evaluation value E is equal to or less than a predetermined allowable value, the color conversion parameter Ajk at this time is output to the color conversion unit 11 (S8). If the evaluation value E is larger than the allowable value, the color conversion parameter is updated. (S19). The color conversion parameter updating process is performed according to the flowchart of FIG.

The above is the operation flow of the color conversion parameter setting operation in the sixth embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, a seventh embodiment will be described.

In the seventh embodiment, the masking amount Ajk (1 <j, k <
The color conversion parameters are calculated for the purpose of determining 3) such that the evaluation function E expressed by the following Expressions 32 to 36 is minimized in the color space.

[0193]

(Equation 32)

[0194]

[Equation 33]

[0195]

(Equation 34)

[0196]

(Equation 35)

[0197]

[Equation 36]

Here, α1 and α2 are appropriate positive numbers,
s, t, and u are appropriate unit vectors in the C, M, and Y color spaces. E1 is Ci, Mi, Y in the C, M, Y color space
i represents the sum of squares of the distances between Pci, Pmi, and Pyi, and E2 is (Ci-Pci, Mi-Pmi, Yi-
Pyi) and the unit vector (s, t,
u) (0 ≦ θi ≦ π / 2) sin ² θ
is the sum of i. The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the direction of the average value of the color shift vector. Can be.

The configuration of the phase-consideration type color conversion unit 2 in the present embodiment is similar to that of FIG. 1 described in the fourth embodiment.
Although the description is omitted because it is the same as that of FIG. 7, the operation process of the color conversion parameter setting will be described with reference to the flowchart of FIG. 21 described in the fourth embodiment. The description of the same parts as those in the fourth embodiment will be omitted, and only different parts will be described. That is, the operation processing of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 will be described.

In step S16, the distance information extraction unit 14 calculates E 34 and outputs E1 as distance information. In step S17, the phase information extracting unit 15 calculates Eq. 35 and outputs E2 as distance information.

In step S18, the color conversion parameter calculation section 16 evaluates the distance information and the phase information obtained as described above by calculating the equation (33). If the evaluation value E is equal to or less than a predetermined allowable value, the color conversion parameter Ajk at this time is output to the color conversion unit 11 (S8). If the evaluation value E is larger than the allowable value, the color conversion parameter is updated. (S19). The color conversion parameter updating process is performed according to the flowchart of FIG.

The above is the flow of the operation processing for setting color conversion parameters in the seventh embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, an eighth embodiment will be described.

In the eighth embodiment, the masking amount Ajk (1 <j, k <
The color conversion parameter is calculated for the purpose of determining 3) such that the evaluation function E expressed by the following equations 37 to 42 is minimized in the color space.

[0206]

(37)

[0207]

(38)

[0208]

[Equation 39]

[0209]

(Equation 40)

[0210]

[Equation 41]

[0211]

(Equation 42)

Here, α1 and α2 are appropriate positive numbers,
E1 is Ci, Mi, Yi and Pc in the C, M, Y color space.
represents the sum of squares of the distances of i, Pmi, Pyi,
E2 is (Ci-Pci, Mi-Pmi, Yi-Pyi)
Is the sum of sin ² ψi of the phase difference ψi (0 ≦ ψi ≦ π / 2) between the color shift vector and the average vector of the color shift vectors. The effect of E1 reduces the distance shift in the color space during color conversion, and the effect of E2 suppresses the shift in the color space during color conversion in the direction of the average value of the color shift vector. Can be.

The configuration of the phase-consideration type color converter 2 in the present embodiment is the same as that of the fourth embodiment described with reference to FIG.
Although the description is omitted because it is the same as that of FIG. 7, the operation process of the color conversion parameter setting will be described with reference to the flowchart of FIG. 21 described in the fourth embodiment. The description of the same parts as those in the fourth embodiment will be omitted, and only different parts will be described. That is, the operation processing of the distance information extraction unit 14, the phase information extraction unit 15, and the color conversion parameter calculation unit 16 will be described.

[0214] In step S16, the distance information extraction unit 14 calculates E1 and outputs E1 as distance information. In step S17, the phase information extracting unit 15 calculates Eq. 40 to output E2 as distance information.

In step S18, the color conversion parameter calculation section 16 evaluates the distance information and the phase information obtained as described above by calculating the equation (38). If the evaluation value E is equal to or less than a predetermined allowable value, the color conversion parameter Ajk at this time is output to the color conversion unit 11 (S8). If the evaluation value E is larger than the allowable value, the color conversion parameter is updated. (S19). The color conversion parameter updating process is performed according to the flowchart of FIG.

The above is the flow of the operation for setting the color conversion parameters in the eighth embodiment.

After setting the color conversion parameters, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

Next, a ninth embodiment will be described.

FIG. 23 schematically shows the configuration of the phase-consideration type color converter 2 according to the ninth embodiment. The ninth embodiment is different from the first embodiment in that the color image recording unit 8
This is an example of a case where the inking portion included in the inside is separated and provided independently of the color image recording portion 8. The first
The same parts as those of the embodiment (FIG. 2) are denoted by the same reference numerals, and description thereof will be omitted. Only different parts will be described.

That is, the color converter 11 and the switch 12
Is connected to the inking unit 17. Inking section 1
7 has the same circuit configuration as the circuit of FIG. 5 described above. Further, a color patch generation unit 13 and a distance information extraction unit 14,
A reverse blackening section 18 is connected to the phase information extracting section 15. The reverse inking unit 18 performs a process reverse to the process of the inking unit 17, and includes, for example, three adders 71a to 71c as shown in FIG.

Next, the operation of setting the color conversion parameters in the above configuration will be described with reference to the flowchart shown in FIG. The same parts as those in FIG. 11 described in the first embodiment are denoted by the same reference numerals, detailed description is omitted, and different parts will be described in detail.

First, the color patch generation unit 13 generates color patch data (fourth color image data) Pci, Pmi, Pci, Pc, and Pc corresponding to the respective color materials of cyan, magenta, yellow, and black.
Pyi and Pki are output (S1) and sent to the switch unit 12 and the reverse blackening unit 17, respectively. When the color conversion parameters are set, the input selection signal is set to “1”, so that the switch unit 12 sets the fourth color image data Pci, Pmi, Pmi
yi, Pki, and the third color image data Co,
Output as Mo, Yo, Ko (S2).

Next, in the color image forming section 8, a duplicate image of one screen of the fourth color image data Co, Mo, Yo, Ko is formed (S3). Next, the color patch data Pci, Pmi,
The color image reading unit 1 reads a duplicate image of Pyi and Pki, and outputs first color image data Ri, Gi and Bi (S4). The first color image data Ri, Gi, Bi output from the color image reading unit 1 are sent to the distance information extracting unit 14 and the phase information extracting unit 15, respectively.

[0224] On the other hand, in the reverse blackening unit 18, the adder 71a, 71b, 71c converts the color patch data Pci, Pmi, Pyi, Pki, which is the fourth color image data input from the color patch generation unit 13, into Pc. 'I = Pci + Pki Pm'i = Pmi + Pki Py'i = Pyi + Pki is added. That is, the reverse process of the inking process of the inking unit 17 is performed, and the color patch data is
Projected onto the M, Y space, and the resulting sixth color image data Pc′i, Pm′i, Py′i are output (S
20).

Next, the distance information extracting section 14 performs color patch data 1 based on the first color image data Ri, Gi, Bi and the sixth color image data Pc'i, Pm'i, Py'i. (Pc′i, P in the color space corresponding to the screen
The distance information between m′i, Py′i) and (Ri, Gi, Bi) is extracted (S5) and output to the color conversion parameter calculation unit 16.

Further, the phase information extracting section 15 generates one screen of color patch data based on the first color image data Ri, Gi, Bi and the sixth color image data Pc′i, Pm′i, Py′i. (Pc′i, P in the color space corresponding to
The phase information of m′i, Py′i) and (Ri, Gi, Bi) is extracted (S6) and output to the color conversion parameter calculation unit 16.

The color conversion parameter calculator 16 calculates the distance information from the distance information extractor 14 and the phase information extractor 1
The color conversion parameter Ajk is calculated based on the phase information from Step 5 and output to the color conversion unit 11 (S7). Color converter 11
Then, the color conversion parameter Ajk output from the color conversion parameter calculation unit 16 is set as a mask amount (S
8).

The above is the flow of the operation processing for setting the color conversion parameters in the ninth embodiment.

After setting the color conversion parameters in this manner, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG. The flowchart of FIG. 26 is different from the flowchart of FIG.
Step S25 for performing the inking process by the inking unit 17 is added between the steps S23 and S23.
Is the same as

Next, a tenth embodiment will be described.

FIG. 27 schematically shows a configuration of the phase-consideration type color converter 2 according to the tenth embodiment. Tenth
The fourth embodiment is an example in which the inking portion included in the color image recording section 8 in the fourth embodiment is separated and independent and provided outside the color image recording section 8. In addition,
The same parts as those of the fourth embodiment (FIG. 17) are denoted by the same reference numerals and the description thereof will be omitted. Only different parts will be described.

That is, the color converter 11 and the switch 12
Is connected to the inking unit 17. Inking section 1
7 has the same circuit configuration as the circuit of FIG. 5 described above. Further, a color patch generation unit 13 and a distance information extraction unit 14,
A reverse blackening section 18 is connected to the phase information extracting section 15. The reverse blackening section 18 is configured as shown in FIG.

Next, the operation processing for setting the color conversion parameters in the above configuration will be described with reference to the flowchart shown in FIG. The same parts as those in FIG. 21 described in the fourth embodiment will be denoted by the same reference numerals, detailed description will be omitted, and different parts will be described in detail.

First, the color patch generation unit 13 generates color patch data (fourth color image data) Pci, Pmi, Pc for cyan, magenta, yellow, and black color materials, respectively.
Pyi and Pki are output (S1) and sent to the switch unit 12 and the reverse blackening unit 18, respectively. When the color conversion parameters are set, the input selection signal is set to “1”, so that the switch unit 12 sets the fourth color image data Pci, Pmi, Pmi
yi, Pki, and the third color image data Co,
Output as Mo, Yo, Ko (S2).

Next, in the color image forming section 8, a duplicate image of one screen of the fourth color image data Co, Mo, Yo, Ko is formed (S3). Next, the color patch data Pci, Pmi,
The color image reading unit 1 reads a duplicate image of Pyi and Pki, and outputs first color image data Ri, Gi and Bi (S4). The first color image data Ri, Gi, Bi output from the color image reading unit 1 are sent to the distance information extracting unit 14 and the phase information extracting unit 15, respectively.

In the reverse blackening section 18, the color patch generation section 13
From the color patch data Pci, Pmi, Pyi, and Pki, which are the fourth color image data input from the CPU, a process reverse to the inking process of the inking unit 17 is performed to convert the color patch data into the C, M, and Y spaces. And the resulting sixth color image data Pc′i, Pm′i, Py′i are output (S26).

The initial value of the color conversion parameter Ajk is output from the color conversion parameter calculation unit 16 to the distance information extraction unit 14 and the phase information extraction unit 15 and is set (S15). The distance information extracting unit 14 includes the sixth color image data Pc′i, Pm ′ from the reverse blackening unit 18.
i and Py'i are also input.

The distance information extracting section 14 is based on the first color image data Ri, Gi, Bi and the sixth color image data Pc'i, Pm'i, Py'i and the initial values of the color conversion parameter Ajk. , Distance information of (Pc′i, Pm′i, Py′i) and (Ri, Gi, Bi) in the color space corresponding to one screen of color patch data is extracted (S16).
Output to the color conversion parameter calculation unit 16.

In the phase information extracting section 15, together with the first color image data Ri, Gi, Bi, the sixth color image data Pc'i, Pm'i, P
y'i is also input.

The phase information extracting unit 15 calculates the first color image data Ri, Gi, Bi and the sixth color image data Pc′i, Pm′i, Py′i and the initial value of the color conversion parameter Ajk. , Phase information of (Pc′i, Pm′i, Py′i) and (Ri, Gi, Bi) in the color space corresponding to one screen of color patch data is extracted (S17).
Output to the color conversion parameter calculation unit 16.

The color conversion parameter calculator 16 calculates the distance information from the distance information extractor 14 and the phase information extractor 1
Based on the phase information from Step 5, a color conversion parameter pass / fail judgment program is executed (S18). If the result of the color conversion parameter pass / fail determination is “good”, the color conversion parameters in the color conversion parameter memory 64 are output to the color conversion unit 11 and set (S8).

If the result of the color conversion parameter pass / fail judgment is “No”, the color conversion parameter calculation program is executed to calculate the color conversion parameters, and the color conversion parameters are stored in the color conversion parameter memory 64 (S19). After the storage, the color conversion parameters in the color conversion parameter memory 64 are sent to the distance information extraction unit 14 and the phase information extraction unit 15, and again
The operations of steps S16 to S18 are repeated.

The above is the flow of the operation for setting the color conversion parameters in the tenth embodiment.

After setting the color conversion parameters in this way, a normal image forming operation of reading a color image of a document and forming a duplicate image is performed according to the flowchart shown in FIG.

[0245]

As described above in detail, according to the present invention, it is possible to calculate and set a color conversion parameter taking into account not only the color difference but also the phase direction, so that a color conversion more visually similar to the color of the original can be achieved. A possible image forming apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram schematically showing a configuration of a phase-consideration type color conversion unit according to the first embodiment.

FIG. 3 is a block diagram schematically illustrating a main configuration of a color conversion unit.

FIG. 4 is a block diagram schematically showing a configuration of a switch unit.

FIG. 5 is a block diagram schematically showing a circuit configuration of an inking unit in the color image forming unit.

FIG. 6 is a block diagram schematically showing a configuration of a color patch generation unit.

FIG. 7 is a block diagram schematically showing a configuration of a distance information extraction unit.

FIG. 8 is a block diagram schematically showing a configuration of a phase information extraction unit.

FIG. 9 is a block diagram schematically showing a configuration of a color conversion parameter calculation unit.

FIG. 10 is a flowchart illustrating a schematic operation process.

FIG. 11 is a flowchart illustrating an operation process of setting a color conversion parameter.

FIG. 12 is an image diagram of first color image data for one screen output from a color patch generation unit.

FIG. 13 is an image diagram of color patch data copied by a color image forming unit.

FIG. 14 is a flowchart for explaining a normal image forming operation process.

FIG. 15 is a flowchart for explaining an operation process of setting a color conversion parameter in the image forming apparatus according to the second embodiment.

FIG. 16 is a flowchart illustrating an operation process of setting a color conversion parameter in the image forming apparatus according to the third embodiment.

FIG. 17 is a block diagram schematically showing a configuration of a phase-consideration type color conversion unit according to the fourth to eighth embodiments.

FIG. 18 is a block diagram schematically showing a configuration of a distance information extraction unit.

FIG. 19 is a block diagram schematically showing a configuration of a phase information extraction unit.

FIG. 20 is a block diagram schematically showing a configuration of a color conversion parameter calculation unit.

FIG. 21 is a flowchart illustrating an operation process of setting a color conversion parameter.

FIG. 22 is a flowchart illustrating an update process when setting color conversion parameters.

FIG. 23 is a block diagram schematically showing a configuration of a phase-consideration type color conversion unit according to a ninth embodiment.

FIG. 24 is a block diagram schematically showing a configuration of a reverse blackening unit.

FIG. 25 is a flowchart illustrating an operation process of setting a color conversion parameter.

FIG. 26 is a flowchart for explaining a normal image forming operation process.

FIG. 27 is a block diagram schematically showing a configuration of a phase-consideration type color conversion unit according to a tenth embodiment.

FIG. 28 is a flowchart illustrating an operation process of setting a color conversion parameter.

[Explanation of symbols]

1 ... Color image reading unit (reading unit), 2 ... Phase consideration type color conversion unit, 8 ... Color image forming unit (image forming unit), 11 ... Color conversion unit (color conversion unit), 12 ... Switch unit 13, color patch generation unit (color sample generation means),
14 ... distance information extraction unit (distance information extraction means), 15 ...
... Phase information extraction unit (phase information extraction unit), 16... Color conversion parameter calculation unit (color conversion parameter calculation unit), 1
7 ... inking unit (first processing means), 18 ... reverse inking unit (second processing means).

Claims (14)

[Claims] 1. A reading means for reading a color image of a document and outputting first color image data, and a first color image data output from the reading means is provided on the basis of a predetermined color conversion parameter. Color conversion means for converting to second color image data corresponding to a color component; and color conversion on the image forming medium using the predetermined color component based on the second color image data output from the color conversion means. A first image forming means for forming a duplicate image of the image forming apparatus, and a color sample for generating third color image data corresponding to the predetermined color component used for image formation in the first image forming means and serving as a color sample Generating means; and a second image form for forming a color duplicate image on the image forming medium using the predetermined color component based on the third color image data output from the color sample generating means. Means for extracting distance information in a color space of a corresponding pixel position from first color image data output from the reading means and third color image data output from the color sample generation means. Extracting means for extracting phase information in a color space of a corresponding pixel position from the first color image data output from the reading means and the third color image data output from the color sample generating means; Information extraction means, color conversion parameter calculation means for calculating the color conversion parameters used in the color conversion means based on the distance information extracted by the distance information extraction means and the phase information extracted by the phase information extraction means, An image forming apparatus comprising: 2. An image according to claim 1, wherein said first and second image forming means are replaced by a switch means and a third image forming means by switching image data by a switch means. Forming equipment. 3. A first reading means for reading a color image of a document and outputting first color image data, and a first color image data outputted from the first reading means for setting a predetermined color Color conversion means for converting to second color image data corresponding to a predetermined color component on the basis of the conversion parameter; and receiving the color data using the predetermined color component based on the second color image data output from the color conversion means. A first image forming unit for forming a color duplicate image on an image forming medium; and a third color image serving as a color sample corresponding to the predetermined color component used for image formation in the first image forming unit. A color sample generating means for generating data; and forming a color duplicate image on the image forming medium using the predetermined color component based on the third color image data output from the color sample generating means. Second image forming means, second reading means for reading a duplicate image on the image forming medium formed by the second image forming means and outputting first color image data, and second reading Calculating a distance in a color space between data corresponding to the third color image data of the first color image data output from the means and the third color image data, and converting the distance into all image data; Distance information extracting means for outputting the sum of the distance information as distance information; data corresponding to the third color image data of the first color image data output from the second reading means; A color misregistration vector which is a difference in a color space from color image data is obtained, an orthogonal projection of the obtained color misregistration vector in a predetermined phase direction is calculated, and this is summed over all image data. The phase information Phase information extraction means for outputting as information, color conversion for calculating the color conversion parameter used in the color conversion means based on the distance information extracted by the distance information extraction means and the phase information extracted by the phase information extraction means An image forming apparatus comprising: a parameter calculation unit. 4. The apparatus according to claim 1, wherein the phase information extracting unit is configured to determine a first color image data output from the second reading unit corresponding to the third color image data and a third color image data. A color misregistration vector which is a difference in a color space is obtained, and an orthogonal projection of each color misregistration vector in a phase direction of an average vector regarding all the image data of the obtained color misregistration vector is calculated. 4. The image forming apparatus according to claim 3, wherein the sum is output as phase information. 5. A reading means for reading a color image of a document and outputting first color image data, and a first color image data output from the reading means is provided on the basis of a predetermined color conversion parameter. Color conversion means for converting to second color image data corresponding to a color component; and color conversion on the image forming medium using the predetermined color component based on the second color image data output from the color conversion means. A first image forming means for forming a duplicate image of the image forming apparatus, and a color sample for generating third color image data corresponding to the predetermined color component used for image formation in the first image forming means and serving as a color sample Generating means; and a second image form for forming a color duplicate image on the image forming medium using the predetermined color component based on the third color image data output from the color sample generating means. A first color image data output from the reading unit and a third color image data output from the color sample generating unit based on a preset color conversion parameter in a color space at a corresponding pixel position. Distance information extracting means for extracting the distance information of the first color image data, first color image data output from the reading means based on a preset color conversion parameter, and third color image output from the color sample generating means Phase information extracting means for extracting phase information in a color space of a corresponding pixel position from data; setting color conversion parameters used in the distance information extracting means and the phase information extracting means; Used by the color conversion means based on the distance information extracted by the means and the phase information extracted by the phase information extraction means. An image forming apparatus comprising: a color conversion parameter calculation unit configured to calculate the color conversion parameter. 6. An image according to claim 5, wherein said first and second image forming means are replaced by a switch means and a third image forming means by switching image data by a switch means. Forming equipment. 7. A first reading means for reading a color image of a document and outputting first color image data, and a first color image data output from the first reading means for converting a first color image data to a preset color Color conversion means for converting to second color image data corresponding to a predetermined color component on the basis of the conversion parameter; and receiving the color data using the predetermined color component based on the second color image data output from the color conversion means. A first image forming unit for forming a color duplicate image on an image forming medium; and a third color image serving as a color sample corresponding to the predetermined color component used for image formation in the first image forming unit. A color sample generating means for generating data; and forming a color duplicate image on the image forming medium using the predetermined color component based on the third color image data output from the color sample generating means. Second image forming means, second reading means for reading a duplicate image on the image forming medium formed by the second image forming means and outputting first color image data, and second reading The first color image data output from the means is color-converted in accordance with a preset color conversion parameter, and the color-converted first color image data corresponding to the third color image data and Third
A distance information extracting unit that calculates a distance in a color space with the color image data, and outputs a sum of the calculated values for all image data as distance information; The first color image data is color-converted according to a color conversion parameter set in advance, and data corresponding to the third color image data of the color-converted first color image data and the third color image data are converted to the third color image data.
A color misregistration vector which is a difference between the color image data and the color image data in the color space is calculated, an angle between the obtained color misregistration vector and a predetermined phase direction is calculated, and this is summed over all image data Phase information extracting means for outputting the phase information as phase information, and setting the color conversion parameters used by the distance information extracting means and the phase information extracting means, and thereafter obtaining the distance information and the phase information extracted by the distance information extracting means. An image forming apparatus comprising: a color conversion parameter calculation unit that calculates the color conversion parameter used by the color conversion unit based on the phase information extracted by the extraction unit. 8. The phase information extracting means color-converts the first color image data output from the second reading means according to a preset color conversion parameter, and converts the color-converted first color image data. A color misregistration vector which is a difference in the color space between the color image data corresponding to the third color image data and the third color image data is obtained, and all the image data of the obtained color misregistration vector is obtained. 8. The image forming apparatus according to claim 7, wherein an angle between the phase direction of the average vector and the obtained color shift vector is calculated, and the sum of the calculated angles is output as phase information. apparatus. 9. The phase information extracting means performs a color conversion on the first color image data output from the second reading means in accordance with a preset color conversion parameter, and performs the color conversion on the first color image data. A color misregistration vector, which is a difference in the color space between the color image data corresponding to the third color image data and the third color image data, is determined. 8. The image forming apparatus according to claim 7, wherein an angle θ of the calculated angle θ is calculated, and a sum of sin ² θ of the calculated angle θ with respect to all image data is output as phase information. 10. The phase information extracting means performs color conversion of the first color image data output from the second reading means according to a preset color conversion parameter,
A color misregistration vector, which is a difference in the color space between the color-converted first color image data corresponding to the third color image data and the third color image data, is obtained. calculates the angle ψ between the color shift vector obtained above and the phase direction of the mean vector of all of the image data of the displacement vector, sin ² this calculated angle ψ
8. The image forming apparatus according to claim 7, wherein a sum of ψ for all image data is output as phase information. 11. A reading means for reading a color image of a document and outputting first color image data, and a black component based on a color conversion parameter set in advance for the first color image data output from the reading means. A color conversion means for converting into second color image data corresponding to a predetermined color component other than the above, and a black component is extracted from the second color image data output from the color conversion means, and the extracted black component is First processing means for outputting as separated third color image data; and, on the image forming medium, using the predetermined color component based on the third color image data output from the first processing means. A first image forming unit for forming a color duplicate image, and fourth color image data corresponding to the predetermined color component used for image formation in the first image forming unit and serving as a color sample A color sample generating means for generating; and a second image for forming a color duplicate image on the image forming medium using the predetermined color component based on the fourth color image data output from the color sample generating means. Forming means; and distributing the black component to other color components by performing inverse processing of the processing performed by the first processing means on the fourth color image data output from the color sample generation means. 5
A second processing means for outputting as the color image data of the first and second color image data; and a pixel position corresponding to the first color image data output from the reading means and the fifth color image data output from the second processing means. A distance information extracting unit for extracting distance information in a color space; a corresponding pixel from first color image data output from the reading unit and fifth color image data output from the second processing unit Phase information extracting means for extracting phase information in the color space of the position; and the distance conversion means used in the color conversion means based on the distance information extracted by the distance information extraction means and the phase information extracted by the phase information extraction means. An image forming apparatus comprising: a color conversion parameter calculation unit configured to calculate a color conversion parameter. 12. The image forming apparatus according to claim 1, wherein the first and second image forming units switch image data by a switch unit.
12. The image forming apparatus according to claim 11, wherein the image forming apparatus is replaced by a switch unit and a third image forming unit. 13. A reading means for reading a color image of a document and outputting first color image data, and a black component based on a color conversion parameter set in advance for the first color image data output from the reading means. A color conversion means for converting into second color image data corresponding to a predetermined color component other than the above, and a black component is extracted from the second color image data output from the color conversion means, and the extracted black component is First processing means for outputting as separated third color image data; and, on the image forming medium, using the predetermined color component based on the third color image data output from the first processing means. A first image forming unit for forming a color duplicate image, and fourth color image data corresponding to the predetermined color component used for image formation in the first image forming unit and serving as a color sample A color sample generating means for generating; and a second image for forming a color duplicate image on the image forming medium using the predetermined color component based on the fourth color image data output from the color sample generating means. Forming means; and distributing the black component to other color components by performing inverse processing of the processing performed by the first processing means on the fourth color image data output from the color sample generation means. 5
A second processing means for outputting as color image data of the first color image data, a first color image data outputted from the reading means based on a color conversion parameter set in advance, and a fifth processing means outputted from the second processing means. Distance information extracting means for extracting distance information in a color space of a corresponding pixel position from color image data; first color image data output from the reading means based on a preset color conversion parameter; Phase information extracting means for extracting phase information in a color space of a corresponding pixel position from the fifth color image data output from the second processing means, and color conversion used in the distance information extracting means and the phase information extracting means Parameters are set, and then the distance information extracted by the distance information extracting means and the phase information extracted by the phase information extracting means are obtained. An image forming apparatus comprising a color conversion parameter calculating means for calculating the color conversion parameters used in the color conversion means based on the phase information, by comprising were. 14. The image forming apparatus according to claim 1, wherein the first and second image forming units switch image data by a switch unit.
14. The image forming apparatus according to claim 13, wherein the switch is replaced by a third image forming unit.