JP3005087B2 - Color copier - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color copying machine, and more particularly to a technique for faithfully copying the color of a document.

[0002]

2. Description of the Related Art With the progress of colorization of OA equipment, "color processing technology" for correctly printing the colors of originals and display images has attracted attention. Such a conventional full-color copying machine includes a color correction unit 5, an image reading unit 6, a printing unit 7, and a memory unit 9, as shown in FIG. In addition, a controller and the like for performing various controls are included, but the description is omitted here because it is not related to the present invention.

The operation of a conventional full-color copying machine will be described with reference to FIG. First, a document is read by the image reading unit 6. The image reading section 6 is configured on the same principle as a conventional full-color scanner.

[0004] The read data is subjected to color correction by a color correction section 5 and is printed out from a printing section 7 as a copy output of a color almost faithful to the original document. The printing unit 7 is configured on the same principle as a conventional full-color printer.

When an arbitrary full-color original is copied, a copy output of the same color as that of the original is not always obtained. This is because the color development of full-color printing utilizes the principle of subtractive color mixture, but in an actual copying machine, the addition rule and the multiplicative rule, which are the basic principles of subtractive color mixture, often do not hold. For this reason, in a full-color copying machine, the color correction is performed by the color correction unit 5.

A commonly used method for color correction is:
Input signals (r, g, b) representing red, green and blue respectively
In this method, a 3 × 3 matrix operation represented by the following equation is performed.

[0007]

(Equation 1)

Where (R, G, B) is the corrected signal, a
₁₁ ~a ₃₃ is a coefficient for color correction. These coefficients are set at the time of product design or shipping, and are always stored and held in the memory unit 9 in FIG.

The color correction unit 5 sequentially performs the operation of Equation 1 while reading out the correction coefficients with reference to the memory unit 9 ,
The data is output to the printing unit 7. As a result, a color-corrected copy output is obtained from the printing unit 7.

The principle of color correction by this method will be briefly described. In subtractive color mixing such as in a full-color copying machine, the inks used (cyan, magenta, and yellow) are each shown in FIG.
As shown in (a), (b) and (c), it is assumed that it has the property of absorbing red, green and blue independently. Fig. 10 (a) (b) (c)
The horizontal axis indicates the wavelength, and the vertical axis indicates the reflectance.

However, the ink actually used is shown in FIG.
As shown in (a), (b), and (c), the characteristics affect each other for red, green, and blue. Therefore, in order to generate a correct color based on the principle of subtractive color mixture, it is necessary to relate the densities of the other two colors in order to determine the print density of a certain ink.

Equation (1) shows such mutual influence relation. By performing color correction using Equation 1 in which coefficients are appropriately determined, it is possible to eliminate the influence on other colors even when using ink having the characteristics shown in FIGS. 11A, 11B, and 11C. Therefore, the printing can be performed by approximating the printing color when the ideal ink of FIG. 10 is used.

Expression 1 shows a method of performing color correction using a 3 × 3 matrix as an example. For example, color correction is performed using a matrix including higher-order terms as shown in Expression 2 of the following expression. May be done.

[0014]

(Equation 2)

In this case, it is possible to perform color correction with higher accuracy than the color correction based on Equation (1).
ol. 18, No. 2, p. 44-48, "Color Masking (II)", Joji Tajima].

In actual color correction, Equations 1 and 2 are realized by hardware or software, and an appropriate DSP or a CPU having high numerical calculation capability is often used. Alternatively, a CPU that is separately held for control
May be shared.

[0017]

Incidentally, since the coefficients in the equations (1) and (2) determine the color reproduction performance of the copying machine, it is necessary to carefully set the values. Conventionally, a method of repeating visual evaluation, a method of least squares, or the like has been used for these setting operations.

When the coefficient is set by the cut and try based on the visual evaluation, there is an advantage that the error that a human actually sees can be minimized. However, since the set values themselves include subjective variations, it is difficult to say that the settings are optimized, and there is a problem that it takes a very long time to perform the optimum settings.

For this reason, it has been difficult to always guarantee a constant color reproduction accuracy when changing the model of a device or updating a lot.

On the other hand, in the method using the least square method or the like,
There is no variation in the set value, and there is an advantage that the set value is optimized in a certain sense. A method of setting each coefficient by this method will be described. Here, a method using multiple regression analysis, which is a kind of the multivariable least square method, will be described.

The multiple regression analysis refers to a plurality of independent variables X _{1 to} X _n.
This is a numerical calculation method for determining the coefficient _ai when the dependent variable Y is described according to the definition of the following equation (3).

[0022]

Equation 3] _{Y = a 1 X 1 + a} 2 X 2 + ‥‥ + a n X n + C However, a _i coefficients for the i th independent variable X _i (i =
1 to n), C is a constant, and n is the number of independent variables.

Here, for example, when the independent variables X _{1 to} X _n are r, g, and b in Equation 1, and Y is R, the coefficients a _{11 to} a ₁₃ can be obtained using multiple regression analysis.

The procedure is as follows.

(Procedure 1) A color chart is measured by a colorimeter and read from an image input device. (Procedure 2) The color chart data read from the image input device is printed and measured with a colorimeter. (Procedure 3) A large number of measurement data are collected, and a multiple regression analysis is performed using the colorimetry data of the original color chart and the data of the printed color chart. (Procedure 4) Y is changed to G and B, and all coefficients are obtained.

The multiple regression analysis is generally established as a numerical calculation program of a computer. Therefore, as long as data is collected, there is an advantage that the coefficient can be determined at high speed without variation by using this method.

However, this method has two problems.
there were. First, it takes a very long time to collect color sample data.
This is a problem that requires much effort. Full regression analysis
The number of variables to be determined (number
(In the case of Equation 2, 10 variables).
It is necessary, but let's collect 100 data
, Even if the procedures 1 and 2 described above are performed in 100 colors
It will be repeated for the number of votes, and this alone will take several hours
It is clear. Next, for example, 100 pieces of data are collected.
Even if it gathers enough color correction coefficients,
What color should I specifically select from the 100 color charts?
There is a problem that it is not clear. Multiple regression analysis
As a result, to obtain satisfactory accuracy, the number of data
Of course, data selection is important. Purpose of color correction
Of course, good color correction for all color ranges
The color chart used for data collection is
If the color is biased near red, for example, the color near red
Even if a good color correction result is obtained, a good color
I can't do it. After all, with the conventional method of performing multiple regression analysis
Takes a lot of time to collect data,
What data should be collected to be good for all colors
Not sure if it will be possible to make any corrections
was there.

The color correction coefficient is set through standard settings at the initial design stage of a product, individual adjustment at the time of shipment, and the like. As described above, in the conventional method, color correction with high color reproduction performance can be obtained. Since the method of setting the coefficients in a sufficiently short time has not been clarified technically, there has been a problem that the setting of the color correction coefficients has not always been carefully performed.

It is desirable to reset the color correction coefficient at the time of maintenance in order to correct the aging of the device performance after the product is shipped. However, due to the structure of the memory unit 9 in FIG. In addition, such a resetting was impossible because a method of setting a highly reliable coefficient with a small variation and a short time was not disclosed.

The present invention has been made in view of the above problems, and has as its object to provide a color copying machine capable of setting a highly reliable color correction coefficient in a short time with little variation.

[0031]

[0032]

The color copying machine according to claim 1, in a color copier to output a printed material of a color signal inputted from the image reading unit from the printing unit and the color correction by the color correction unit, signal input and output for performing data transmission and reception Color through department
An external device which is detachable from the main body of the copying machine;
Is a reference pattern data generation unit, a color value conversion unit,
And a reference pattern data generating section.
The same as changing to multiple gradations according to the color signal
Reference pattern provided to make each color distribution equal in the plane
Generating color data, wherein the color value conversion unit generates the reference pattern.
The reference pattern data generated by the data generation unit;
A mark obtained by printing pattern data by the printing unit
Data obtained by reading printed matter by the image reading unit
Into a color value based on the perceptual characteristic,
Is a color based on the perceptual characteristic converted by the color value conversion unit.
Color correction coefficients are set so that the error between
Calculated, the color correction unit is calculated by the arithmetic unit
Performing a color correction operation using the corrected color correction coefficient.
You. A color copying machine according to claim 2, wherein the color correction unit color-corrects the color signal input from the image reading unit and outputs the color signal as a printed matter from the printing unit.
Color copier main unit via signal input / output unit that sends and receives data
An external device detachable from the body, wherein the external device is the reference device;
A pattern data generating unit; and a calculating unit,
The quasi-pattern data generation unit
By changing to multiple gradations, each color distribution is equal in the same plane.
Generate reference pattern data provided so that
The calculation unit is configured to generate the base pattern generated by the reference pattern data generation unit.
Printing the reference pattern data and the reference pattern data
The printed matter obtained by printing at the image reading unit is read by the image reading unit.
Error between the data obtained
An operation unit for calculating a color correction coefficient, and the color correction unit
Color correction using the color correction coefficient calculated by the arithmetic unit
The operation is performed. Further, in the color copying machine according to either of claims 1 or claim 2, the reference pattern data generated by said reference pattern data generating unit is an image data of a square number of pixels in the vertical and horizontal directions are equal, the color signal Is an rgb signal. Each color data when the quantization bit is set to 8 bits corresponding to each rgb signal is represented by (r, g, b) = (0, 0,0), (r, g, b) = (255,255,255) at the center position, and (r, g, b) = (255,0,255) at the center position of each side.
0), (0, 0, 255), (0, 255, 0), (2
55, 255, 0). Further, in the color copying machine according to either of claims 1 or claim 2, the reference pattern data generated by said reference pattern data generating unit is an image data of a square number of pixels in the vertical and horizontal directions are equal, the color signal Is the rgb signal
When the quantization bit is set to 8 bits corresponding to each of the rgb signals, each color data is converted into 4 bits of the square image data.
At the position of the vertex, (r, g, b) = (0, 0, 0),
At the center of each of the two opposing sides, (r, g,
b) = (255, 255, 0), (0, 0, 255), and (r, g, b) = (255, 0, 0) at the equally divided three sides of each of the other two opposite sides. ), (255, 0,
0), (0, 255, 0), (0, 255, 0),
At the position of the intersection of the line connecting the central positions of the two opposing sides and the line connecting the three equal parts of the other opposing sides without intersecting each other , (R, g,
b) = (255, 255, 255), (255, 25)
5,255) is desirable. Further, in the color copying machine according to either of claims 1 or claim 2, the reference pattern data generated by said reference pattern data generating unit is an image data of a square number of pixels in the vertical and horizontal directions are equal, the color signal Is the rgb signal, r
Each of the color data when the quantization bit is set to 8 bits corresponding to each of the gb signals is (r, g, b) = (0, 0, 0) at the positions of the four vertices of the square image data. At the center of each of the two sides (r, g, b) =
(255, 255, 255), (0, 0, 255), and (r, g, b) = (0, 0, 0), ( 255,0,
0), (0, 255, 0), (0, 0, 0), and a line connecting the positions of the centers of the two opposing sides and the three opposing sides of the other two sides. At the position of the intersection with the line connecting the equally divided positions without intersecting, (r, g, b) =
(255, 255, 0), (255, 255, 255)
Is desirable.

[0034]

The reference pattern data generating section for generating color reference pattern data generates a pattern used as a reference for measuring a color reproduction error. The reference pattern data generated by the reference pattern data generation unit, and the reference pattern obtained by reading the printed matter obtained by printing the reference pattern data by the printing unit normally included in the copying machine by the image reading unit normally included in the copying machine In the color value conversion unit that converts the data of the reference pattern into color values based on the perceptual characteristics, the reference pattern data generated by the reference pattern data generation unit and the color reproduction error of the printing unit and the image reading unit are added to this data. Convert the data to color values based on perceptual properties.

The arithmetic unit calculates the color correction coefficient between the two data converted into the color values based on the perceptual characteristics in a short time.

Since the reference pattern is configured to include as many colors as possible in the color space, it is possible to collect data on many colors in one behavior. The color correction coefficients calculated based on this data represent color reproduction distortions for many colors on average.

As an effect of this, it is necessary to find and set an optimum color correction coefficient in a short time and with a minimum effort in all stages such as maintenance, not to mention the initial design of the product and adjustment at the time of shipment. Will be able to

Further, a rewritable memory unit for storing the color correction coefficients calculated by the arithmetic unit holds the calculated color correction coefficients. A color correction unit that performs a color correction operation using a color correction coefficient stored and held in a memory unit performs color correction with reference to the color correction coefficient.

With these functions, it is possible to always carry out the optimum color correction even if the equipment after shipment changes over time, and it is possible to always obtain a copy output faithful to the color of the original. In addition, the color reproduction performance of the device can be maintained in the best condition without variation, and the signal input / output unit for transmitting / receiving data to / from the external device receives the reference pattern data received from the external device. The received data is printed by the printing unit, and the reading unit reads the print data and transmits the image data to an external device via the signal input / output unit.

A color correction coefficient calculated by an external device based on the above data is received by the signal input / output unit,
The received data is stored in a rewritable memory unit.
The color correction unit performs color correction using the color correction coefficients stored in the memory unit.

Thus, the reference pattern data generator,
A color correction coefficient is calculated by an external device including a calculation unit or a color value conversion unit , and the color copier receives the result and uses the result for color correction, so that the configuration of each color copier without impairing the above-described effects. Has the effect of simplifying the operation.

[0042]

FIG. 1 shows an example of a functional configuration of a full-color copying machine according to a reference example of the present invention . As compared with the conventional copying machine shown in FIG. 9, a reference pattern data generation unit 1, a color value conversion unit 2, a multiple regression analysis operation unit 3 are provided, and a memory unit 4 is rewritable. Is the feature. How these parts are used to solve the problems described above will be described in detail.

First, how to calculate the color correction coefficient will be described. FIG. 2 shows a flowchart for determining the color correction coefficient. In the method according to the present invention, for as many colors in the color space as possible in one behavior, the original colors and the colors passed through the printing unit and the image input unit are grasped, and these colors are converted into color values based on perceptual characteristics. The operation is performed so as to obtain the coefficient for performing the color correction in the multiple regression analysis operation unit.

Hereinafter, description will be made with reference to FIGS. First, in S1, a reference pattern including as many colors as possible in the color space is generated from the reference pattern data generation unit 1. The reference pattern data generating unit 1 is configured by a storage device such as a ROM or a hard disk, and stores data of a separately generated reference pattern image.

The image size is 512 pixels × 512 pixels,
Assuming that the number of quantization bits is 8 bits, the capacity of these storage devices is as follows.

[0046]

## EQU00004 ## From 512 (pixels) .times.512 (pixels) .times.3 = 786432, about 786,432 bytes are required.

The reference pattern image represents many colors in the color space.
Images should be included evenly . FIGS. 3 and 4 show examples of such a reference pattern image. Both are square drawings
The specific points of the image are determined in advance, and the data of the points between them are coordinates
Is determined by interpolation according to. The square in Figure 3
Specifically, the image data represents the values of red r, green g, and blue b,
At the positions of the four vertices of the square image data, (r, g,
b) = (0,0,0), and (r, g,
b) = (255, 255, 255) and the center of each side
At the position, (r, g, b) = (255, 0, 0), (0,
0, 255), (0, 255, 0), (255, 25
5,0), and data other than these positions are
It is determined by interpolation according to the distance from. The data in Fig. 4
It is determined in the same manner as in FIG. Although various configurations of the reference pattern image are conceivable, no matter how the colors included in the reference pattern image are spatially arranged to form the reference pattern image, the distribution of the colors in the color space is equal. For example, the present invention exerts the same effect.

Therefore, the difference in the distribution of the colors constituting the image in the color space is more important than the appearance of the reference pattern. For example, the reference pattern images shown in FIGS. 5 and 6 have different appearances from the images shown in FIGS. 3 and 4, but have exactly the same distribution of colors in the color space. It can be considered an image. There are many types of such images.

By the way, in such a reference pattern image, it is considered that one pixel corresponds to a color chart of one color according to the prior art. Therefore, by using such a reference pattern image, it is possible to expect at least an effect equivalent to the case where the coefficient is calculated using a very large number of color patches in the related art. As the reference pattern, a pattern in which a plurality of pixels correspond to one color chart can be easily configured. Ma
Also, this reference pattern image contains many colors evenly.
The color space in the prior art.
Calculation of coefficients using data on all colors evenly
The same effect can be expected as when performing

Next, in S2, this data is printed using the printing unit 7 normally provided in the copying machine, and in S3, the printed matter is input using the image reading unit 6 normally provided in the copying machine. These operations can be performed by the user himself.

The data input here is converted into reference pattern data generated in advance by printing unit 7 and image reading unit 6.
Is added. Therefore, it is expected that some difference occurs between the previously generated reference pattern data and the read reference pattern data. This corresponds to a color reproduction error when a normal document is copied.

Further, in S4, the color value conversion unit 2 converts the previously generated reference pattern data and the read reference pattern data into color values based on perceptual characteristics. This is to evaluate the color reproduction error based on human visual characteristics. By performing this conversion, the color reproduction error can be visually minimized.

As such color values,

[0054]

(Equation 5)

And

[0056]

(Equation 6)

(Hereinafter, “Lab” in the text means the above equation (5)).

For example, the conversion into the Lab value is performed based on the following equation.

[0059]

(Equation 7)

The color value converter 2 can be easily constructed using a microcomputer in which the above equation is programmed or a suitable DSP.

Further, in S5, the multiple regression analysis operation unit 3 uses these data to determine a correction coefficient required for color correction.

As described above, the reference pattern image is 1
A pixel corresponds to a color chart of one color. Therefore, in the multiple regression analysis, the same color patches (pixels representing the same color) of the previously generated reference pattern data and the read reference pattern data converted into the color values based on the perceptual characteristics by the color value conversion unit 2 are associated with each other. Need to run.

For this reason, when the user reads the printed reference pattern in step S3 described above, it is necessary for the user to place the printed matter in a correct position. This can be easily achieved by providing the image reading unit 6 with an appropriate marking.

The coefficients obtained by the multiple regression analysis operation unit 3 in this manner correspond to the matrix coefficients of Expressions 1 and 2. The multiple regression analysis operation unit 3, like the color value conversion unit 2,
If a general regression analysis method is configured with a microcomputer programmed, the coefficients can be easily obtained.

The parts such as the reference pattern data generator 1, the color value converter 2, the multiple regression analysis calculator 3 and the like described above perform all functions if there is an appropriate storage device and a programmed microcomputer. be able to. Since these storage devices and microcomputers are generally incorporated in the apparatus as firmware for a copying machine for control purposes or the like, the present invention can be implemented simply by newly incorporating a program for executing the above-described functions. Can be applied.

In S6, the color correction coefficients obtained in this manner are stored and held in the rewritable memory unit 4.
The memory unit 4 always holds the latest color correction coefficient. The values in the standard state at the time of product shipment may also be held. The memory unit 4 can be easily constituted by an EEPROM or a hard disk and can be made rewritable, so that the object of the present invention can be achieved.

The above operation will be described more specifically with reference to FIG. First, the reference pattern data generated by the reference pattern data generation unit 1 is guided to the printing unit 7 and the color value conversion unit 2. Here, the data guided to the printing unit 7 is used for printing the reference pattern in the first stage of the flowchart shown in FIG. On the other hand, the data guided to the color value conversion unit 2 is used to be converted into a color value based on a perceptual characteristic such as a Lab color value.

The reference pattern printed by the printing unit 7 is read from the image reading unit 6 by the user. This data is first guided to the color value conversion unit 2 and is converted into a color value based on perceptual characteristics, such as a Lab color value.

The two color data converted by the color value conversion unit 2 are led to a multiple regression analysis operation unit 3, where they are subjected to multiple regression analysis to obtain a color correction coefficient. The color correction coefficient data is guided to the memory unit 4 and stored therein.

Finally, color correction is performed by the color correction unit 5 using the data held in the memory unit 4. That is, when a document to be copied is read from the image reading unit 6, the data is guided to the color correction unit 5, and the color correction unit 5 refers to the color correction coefficient data stored in the memory unit 4, A correction operation is performed and output to the printing unit 7.
Another reference example is shown in FIG. In the present reference example, the color value converter 2 in FIG. 1 is omitted. The color value conversion unit 2 shown in FIG. 1 is intended to evaluate color reproduction errors based on human visual characteristics and determine color correction coefficients. Therefore, one of the objects of the present invention is to simplify adjustment. In the case where “and shortening of time” are the most important, the color value conversion unit 2 may be omitted.

The present embodiment does not include the color conversion unit 2, and the operation of each component is the same as that described with reference to FIG.

FIG. 8 shows the configuration of this embodiment. In this embodiment, the reference pattern data generating unit 1 of FIG. 1 described in the previous Example, the color value converter unit 2, a multiple regression analysis calculation unit 3, an external device by adding new signal input unit 8b (FIG. 8 (a portion surrounded by a broken line).

Further, a signal input / output unit 8a is newly added to the memory unit 4, the color correction unit 5, the image reading unit 6, and the printing unit 7 in FIG.
To form the color copying machine of this embodiment. The signal input / output unit 8a sends and receives various data between the external device and the color copier.

The reference pattern data generator 1 of the external device,
The color value conversion unit 2 and the multiple regression analysis operation unit 3 are usually used only for maintenance after the product is shipped after the adjustment is completed. The configuration can be simplified, and cost reduction of the device itself can be expected.

In this embodiment, a color correction coefficient similar to that described in the preceding reference example is obtained by using the reference pattern data generator 1, color value converter 2, and multiple regression analysis operation unit 3 provided in an external device. , As follows.

First, as shown in FIG. 8, the signal input / output unit 8a of the color copying machine is connected to the signal input / output unit 8b of the external device. These signal input / output units 8a for inputting / outputting data
And 8b are, for example, RS232C, SCSI, GP-
It can be configured based on a standard interface such as IB.

The signal input / output unit 8a is connected to the printing unit 7, the image reading unit 6, the rewritable memory unit 4, etc.
The transmission and reception of data between these and an external device is made possible. The signal input / output unit 8b is similarly connected to the reference pattern data generation unit 1, the color value conversion unit 2, and the multiple regression analysis operation unit 3.

The external device transmits the reference pattern data from the reference pattern data generator 1 to the color copier via the signal input / output unit 8b. The signal input / output unit 8a receives the data. The printing unit 7 prints the received data to obtain a print output. Next, the printed material is read by the image reading unit 6, and the read data is transmitted to an external device via the signal input / output unit 8a. The data is received by the signal input / output unit 8b and reaches the color value conversion unit 2.

The color value conversion unit 2 of the external device converts the generated reference pattern data and the data output from the image reading unit 6 into, for example, Lab color values. Further, the multiple regression analysis operation unit 3 obtains a regression coefficient based on these, and transmits it as a color correction coefficient to the color copying machine via the signal input / output unit 8b.

On the color copier side, the color correction coefficients are stored in a rewritable memory unit 4 capable of storing data transmitted from an external device. This coefficient is ahead of
It is clear that the color correction coefficient is exactly the same as that obtained in the reference example. On the color copier side, color correction is performed by the color correction unit 2 using the data held in the memory unit 4.

That is, when a document to be copied is read from the image reading unit 6, the data is guided to the color correction unit 5, and the color correction unit 5 refers to the color correction coefficient data stored in the memory unit 4. In addition, while performing the calculation of the color correction, it outputs to the printing unit 7.

As described above, the reference pattern data generator 1, color value converter 2, multiple regression analysis calculator 3
Has the same functions as those described with reference to FIG. 1, and it is sufficient that data can be exchanged between the external device and the color copier. The external device could be a dedicated device, a notebook handheld computer, or the like.

The color value converter 2 can be omitted if necessary, as described in another reference example.

[0084]

In the present invention as described above, according to the present invention, suitable many colors
Since using the reference pattern disposed off, or in the color space
Color correction data related to evenly arranged color chart data
Can be collected in one behavior . By using this data in a method such as the least squares method, it is possible to calculate a color correction coefficient having no variation in a very short time.

Further, in the present invention, when determining the coefficients of the color correction circuit, the data is converted into Lab color values or the like for the purpose of evaluating the color reproduction errors measured for many colors in proportion to the visual values. Since the color value is converted into a color value based on the perceptual characteristic, the coefficient can be set to a visually optimum value at high speed without variation.

As a result, the reliability of the set values at the stage of the initial design of the product and the adjustment at the time of shipment can be improved, and the performance of the product can be improved. Also, the adjustment time can be shortened, which is effective in reducing costs.

Further, even in the maintenance stage for correcting the aging, the operation of resetting the coefficient value without variation is completed in a short time, so that the product is always expensive at a very low cost. Performance can be maintained.

Further, the operation of resetting the coefficient is extremely simple, and the maintenance itself can be performed by the user himself. As described above, since the product embodying the present invention is maintenance-free, there is an effect unique to the present invention that the cost relating to the manufacture and sale of a copying machine can be greatly reduced from a comprehensive viewpoint.

Further, according to the first or second aspect of the present invention, cost reduction can be expected by separating parts required for maintenance. Since the detached portion can be easily carried by a service person or the like, it is extremely effective for maintenance.

As described above, according to the present invention, it is possible to realize a color copying machine which can contribute to the cost reduction and the improvement of the performance of the product as well as can faithfully reproduce the color of the original.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a reference example according to the present invention.

FIG. 2 is a flowchart for determining a color correction coefficient according to the present invention.

FIG. 3 is a diagram showing an example (1) of a reference pattern used in the present invention.

FIG. 4 is a diagram showing an example (2) of a reference pattern used in the present invention.

FIG. 5 is a diagram showing a reference pattern having the same effect as the reference pattern of FIG. 3;

6 is a diagram showing a reference pattern having the same effect as the reference pattern of FIG.

FIG. 7 is a configuration diagram showing a reference example according to the present invention.

8 is a block diagram showing an embodiment of the present invention.

FIG. 9 is a configuration diagram of a conventional copying machine.

FIG. 10 is a characteristic diagram showing ideal ink absorption characteristics.

FIG. 11 is a characteristic diagram showing actual ink absorption characteristics.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reference pattern data generation part 2 Color value conversion part 3 Multiple regression analysis operation part 4 Memory part (rewritable) 5 Color correction part 6 Image reading part 7 Printing part 8a Signal input / output part on the copying machine side 8b Signal on the external device side Input / output unit 9 Memory unit (non-rewritable)

Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (5)

(57) [Claims] 1. A color copier for color-correcting a color signal input from an image reading unit by a color correction unit and outputting the color signal as a printed matter from a printing unit, via a signal input / output unit for transmitting and receiving data. Color copier book
An external device detachable from the body, the external device comprising : a reference pattern data generator; and a color value converter.
And a calculation unit, wherein the reference pattern data generation unit corresponds to each color signal.
To change to multiple gradations and to distribute each color in the same plane
Generates reference pattern data provided so that
The color value conversion unit generates the color data in the reference pattern data generation unit.
Generated reference pattern data and the reference pattern data
The printed matter obtained by printing by the printing unit is read by the image reading.
The data obtained by reading in the embedding section
Based on the perceived characteristics converted by the color value conversion unit.
Color so that the error between the color value data based on
Calculating a correction coefficient, wherein the color correction unit calculates the color correction calculated by the calculation unit;
Color characterized by performing color correction operation using coefficients
Copy machine. 2. A color copier in which a color signal input from an image reading unit is color-corrected by a color correction unit and output as a printed matter from a printing unit, via a signal input / output unit for transmitting and receiving data. Color copier book
An external device detachable from the body, the external device comprising: the reference pattern data generating unit;
And the reference pattern data generating section corresponds to each color signal.
To change to multiple gradations and to distribute each color in the same plane
Generates reference pattern data provided so that
And the calculation unit generates the reference pattern data in the reference pattern data generation unit.
The reference pattern data and the reference pattern data
The printed matter obtained by printing in the printing unit is read by the image reading unit.
Error between data obtained by reading with
A calculation unit for calculating a color correction coefficient so, the color correction section, color correction calculated by the arithmetic unit
Color characterized by performing color correction operation using coefficients
Copy machine. 3. The reference pattern data generated by the reference pattern data generation section is square image data having the same number of vertical and horizontal pixels, and the color signal is an rgb signal. Each color data when the quantization bit is 8 bits is (r, g, b) = (0, 0, 0) at the positions of the four vertices of the square image data, and (r, g) at the center position. , B) = (255, 255, 25)
5) and (r, g, b) = (2) at the center of each side.
55,0,0), (0,0,255), (0,255,
3. The color copying machine according to claim 1, wherein (0), (255, 255, 0). 4. The reference pattern data generated by the reference pattern data generating section is square image data having the same number of vertical and horizontal pixels, and the color signal is an rgb signal. Each color data when the quantization bit is 8 bits is (r, g, b) = (0, 0, 0) at the positions of the four vertices of the square image data, and each of the two opposite sides is (R, g, b) at the center of the side
= (255,255,0), (0,0,255),
At the position where each of the other two opposing sides is equally divided into three, (r,
g, b) = (255,0,0), (255,0,0),
(0,255,0), (0,255,0), and the line connecting the center positions of the two opposing sides and the other opposing sides are equally divided into three. At the position of the intersection with the line connected without intersecting the positions, (r, g, b) =
(255, 255, 255), (255, 255, 25
3. The color copying machine according to claim 1, wherein the color copying machine is set to 5). 5. The reference pattern data generated by the reference pattern data generating section is square image data having the same number of vertical and horizontal pixels, and the color signal is an rgb signal. Each color data when the quantization bit is 8 bits is (r, g, b) = (0, 0, 0) at the positions of the four vertices of the square image data, and each of the two opposite sides is (R, g, b) at the center of the side
= (255, 255, 255), (0, 0, 255) and (r, g, b) = (0, 0, 0), (255, 0,
0), (0, 255, 0), (0, 0, 0), and a line connecting the positions of the centers of the two opposing sides and the three opposing sides of the other two sides. At the position of the intersection with the line connecting the equally divided positions without intersecting, (r, g, b) =
(255, 255, 0), (255, 255, 255)
3. A color copying machine according to claim 1, wherein