JPH08294011A - Image processing unit, its method and system - Google Patents

Abstract

PURPOSE: To provide the image processing unit and its method by which a color of an output image by the image processing unit is equal to the color obtained by offset printing by taking under-color reduction(UCR) in the offset printing and a characteristic of an output equipment into account. CONSTITUTION: A K component of a received CMYK signal only is given to a distribution processing section 20, in which shares ΔC, ΔM, ΔY to other CMY component are decided by taking the UCR in the offset printing into account. Then, each color component of the CMY signal is added by an arithmetic circuit 30, the sum is converted into an RGB signal by a conversion section 40 by referencing a prescribed LUT taking the color reproducibility of a display section 200 into account and the signal is displayed on a display section 200.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus and method and system, and more particularly to an image processing apparatus and method and system for visualizing a full color image.

[0002]

2. Description of the Related Art In recent years, a color plate making system including a personal computer, a full-color scanner, a film scanner, a full-color high-definition display, a full-color printer, application software, etc. has become widespread due to its low price and high functionality. There is. As a result, among the work processes in full-color offset printing, which were not easily performed in the past, until the color comp, which is a printing sample, is created by the operator of the color plate making system at a relatively low cost and in a short period of time. It is becoming possible to do it.

Generally, in offset printing, a color is mixed by changing the halftone dot area ratio of each offset ink of C (cyan), M (magenta), Y (yellow), and K (black), and printing is performed. Often output. Therefore, in order to create a color comp for offset printing by the color plate making system, it corresponds to the halftone dot area ratio of C, M, Y, and K inks in offset printing (hereinafter referred to as CMYK halftone dot area ratio). Live CM
It is necessary that the tint of the output image obtained when the input image represented by the YK image signal is input to the color plate making system for processing and output is almost the same as the tint in the printing result of the offset printing. Become.

Regarding the conventional method for making the tint of the color plate making system almost equal to the tint of the offset printing,
This will be described below.

As an example of a structure for outputting an image in a color plate making system, a color display is taken as an example.
In the input image represented by the CMYK image signal corresponding to the CMYK halftone dot area ratio, R (red), G (green) is obtained by taking the complement of the signal value level "255" for each C, M, Y signal. ), B (blue) signal. Then, the output image is displayed on the screen of the color display based on the obtained RGB signal values.

As an example of a structure for performing image output in a color plate making system, a full-color printer is taken as an example, and in the input image represented by CMYK image signals corresponding to the CMYK halftone dot area ratio, the respective C, M, Y, and K
Correction is performed by multiplying the signal by a predetermined coefficient. By this correction, the difference between the tint of the output image output by the full-color printer and the tint of the print result of offset printing is corrected, and thus full-color output with the tint equivalent to that of offset printing is possible.

[0007]

However, the above-mentioned conventional example has the following problems.

For example, in the case where the structure for outputting an image in a color plate making system is a color display, a CM
Although it is converted into an RGB signal by taking the complement of the CMY components of the input image represented by the YK signal, this method does not process the K signal in the input image. Therefore, the K component is not taken into consideration in the tint displayed on the color display, and therefore, it is not always the same as the tint in the offset printing result. Incidentally, C
It is possible to convert the MYK signal into an RGB signal in consideration of the K component, for example, by considering stochastic overlap of respective color inks and dot arrangement according to the Neugebauer equation, but this method is complicated. Since the calculation is required, the processing becomes complicated, resulting in an increase in processing time and an increase in cost.

On the other hand, when the configuration for outputting an image in the color plate making system is a full color printer, CMY
For each CMYK component of the input image represented by the K signal,
It is corrected by multiplying it by a predetermined coefficient. In this method, K
Since the components are taken into consideration, the above problem does not occur. However, since only CMYK signals are handled, it is not possible to deal with the case of outputting in other signal formats such as RGB signals.

In any of the above methods,
The input image signal represented by the CMYK signal is uniformly complemented or multiplied by a coefficient. That is, the difference in color reproducibility due to the configuration for outputting an image, for example, the difference in color reproducibility due to the device color reproduction method is not taken into consideration. Therefore, for example, even when a correction is applied to a certain tint, it is necessary to uniformly take a complement or multiply it by a predetermined coefficient, which will affect all other tints.

Due to the various problems described above,
In the conventional color plate making system, it was difficult to make the tint of the output image equal to that of the offset printing.

The present invention has been made to solve the above-mentioned problems, and by taking into consideration the undercolor removal (UCR) in offset printing and the characteristics of the output device, the tint of the output image by the image processing device is considered. It is an object of the present invention to provide an image processing apparatus, a method thereof, and a system in which the color tone is equivalent to that obtained by offset printing.

[0013]

In order to achieve the above object, the image processing apparatus of the present invention has the following configuration.

That is, input means for inputting a color image signal of the first format, and a distribution amount for determining a distribution amount for distributing the black component of the color image signal of the first format to color components other than black in the first format. Determining means, adding means for adding the distribution amount to color components other than black of the first format color image signal, and color components other than black of the first format color image signal added by the adding means. The distribution amount determination means and the distribution amount determination means and the output means for outputting the color image signal of the second format converted by the conversion means, and the conversion means for converting the color image signal of the second format different from the first format. The conversion means is characterized in that the distribution amount is determined and converted into the second format based on the color reproducibility of the output means.

For example, the first format is a CMYK density expression, and the second format is a RGB brightness expression.

For example, the first format is a density expression in CMYK corresponding to a halftone dot area ratio in offset printing.

For example, the output means displays and outputs the color image signal of the second format.

For example, the output means prints out the color image signal of the second format.

For example, the distribution amount determining means determines the distribution amount by referring to a table.

For example, the table reads a pattern image composed of CMY components by offset printing as an RGB signal and creates a first table in which the RGB signal and the CMY component are associated with each other, and the RGB signal and the output means are provided. A second table corresponding to RGB signals that can be processed in step S3 is created, and the first table and the second table are combined to create a third table. It is a table created by reading as a signal, converting the RGB signal into a CMY signal by referring to the second table and the third table, and associating the K component with the CMY signal. .

For example, the conversion means is characterized in that conversion is performed by referring to a table.

For example, the tables are the first table and the second table.

For example, the table is the third table.

For example, the pattern image composed of the CMY components and the pattern image composed of the K components have a plurality of gradations for each component.

In order to achieve the above object, the image processing method of the present invention includes the following steps.

That is, an input step of inputting a color image signal of the first format, and a distribution amount for determining a distribution amount for distributing the black component of the color image signal of the first format to color components other than black in the first format. A determination step; an addition step of adding the distribution amount to a color component other than black of the color image signal of the first format; and a color component other than black of the color image signal of the first format added by the addition step. The method further comprises a conversion step of converting into a color image signal of a second format different from the first format, and an output step of outputting the color image signal of the second format converted by the conversion step. In the conversion step, the distribution amount is determined and the conversion into the second format is performed based on the color reproducibility in the output step.

In order to achieve the above object, the image processing system of the present invention has the following configuration.

That is, input means for inputting a color image signal of the first format, and a distribution amount for determining a distribution amount for distributing the black component of the color image signal of the first format to color components other than black in the first format. Determining means, adding means for adding the distribution amount to color components other than black of the first format color image signal, and color components other than black of the first format color image signal added by the adding means. The distribution amount determination means and the distribution amount determination means and the output means for outputting the color image signal of the second format converted by the conversion means, and the conversion means for converting the color image signal of the second format different from the first format. The conversion means is characterized in that the distribution amount is determined and converted into the second format based on the color reproducibility of the output means.

[0029]

With the above-described structure, the second type color image signal is removed from the first type color image signal by taking the black component amount into consideration to remove the black component and the color reproducibility of the output means. Can be converted to.

Therefore, the RG capable of processing the CMYK signals corresponding to the halftone dot area ratio in the offset printing by the output means.
Since the conversion to the B signal can be appropriately performed, the unique effect that the tint of the image output from the image processing apparatus can be made substantially the same as the tint obtained by the offset printing is obtained.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the arrangement of the image processing apparatus according to this embodiment. In FIG. 1, an image processing unit 100 is connected to a display unit 200 such as a color monitor and a print output unit 300 such as a color printer. A host computer 400 is connected to the image processing unit 100 via an interface. An image input unit 500 such as a scanner reads a document image and inputs it to the image processing apparatus. An operation unit 600 such as a keyboard is used to input instructions and data from an operator to the system.

FIG. 2 shows a detailed configuration of the image processing section 100. In FIG. 2, 10 is, for example, the host computer 4
00 is an image memory that stores image signals expressed by CMYK. Of course, the image signal stored in the image memory 10 may be one created by the image processing apparatus itself, or one read by the image input unit 500 such as a scanner,
It may be read from an external storage device or the like (not shown) connected to the image processing unit 100.

Reference numeral 20 denotes a distribution processing unit, which refers to the LUT unit 50 and distributes the K component of the CMYK image signals stored in the image memory 10 to the other three color components C, M, and Y. Determine the quantities ΔC, ΔM, ΔY. Distribution processing unit 20
The details of will be described later. 30 is an addition processing unit,
Of the input CMYK image signals, C, M, and Y components excluding the K component are determined by the distribution process 20.
Add C, ΔM, and ΔY, respectively. A conversion processing unit 40 refers to the LUT unit 50 and converts the image signal represented by CMY into a format that can be output on the display unit 200, that is, an RGB format that can be displayed on a color monitor or the like.

The LUT unit 50 is composed of a RAM,
It has a plurality of LUTs such as a first LUT 51, a second LUT 52, a third LUT 53, a fourth LUT 54 and the like. Each of these LUTs will be described later.

Reference numeral 60 denotes a CPU, which centrally controls each component of the image processing unit 100 described above. Reference numeral 61 denotes a ROM, which holds a control program executed by the CPU 60, fixed variables, and the like. Reference numeral 62 is a RAM that serves as a work area for the CPU 60.

The RGB signals output from the image processing device are input to the display unit 200 and visualized on the screen.

Hereinafter, the image processing unit 10 having the above-mentioned configuration
The operation at 0 will be described in more detail.

Of the CMYK image signals stored in the image memory 10, only the K component excluding the C, M and Y components is input to the distribution processing section 20. In the distribution processing unit 20, the amount Δ for distributing the K component in the input image signal into the C, M, and Y components.
A fourth LUT prepared in advance in the LUT unit 50 is used to determine C, ΔM, and ΔY. Hereinafter, a method of creating the fourth LUT will be described with reference to FIG.

FIG. 3 is a flow chart of a process for creating each LUT in the LUT unit 50. Before starting this process, it is necessary to prepare the offset printed matter shown in FIGS. 4 and 5 in advance.

FIG. 4 shows an image pattern (CMY pattern) in consideration of a combination of CMY components. In the CMY pattern shown in FIG. 4, the halftone dot area ratio of each C, M, and Y component visualized by offset printing is divided into eight from the minimum value to the maximum value, and the hues of all 729 patterns are obtained by the combination. Is presenting. That is, C
As shown in FIG. 4, for example, by providing sample points of nine kinds of halftone dot area ratios of C0 to C8 as components, M0 to M8 as M components, and Y0 to Y8 as Y components, and offset printing of all combinations thereof. CMY pattern. Since there is no K component in this CMY pattern, that is, the halftone dot area ratio of the K component is always 0%.

Further, FIG. 5 shows an image pattern (K pattern) consisting of only the K component, which is a so-called gray scale.
In the K pattern shown in FIG. 5, the C, M, and Y components are all 0% in the CMYK halftone dot area ratio, and an image pattern (gray scale) in which only the K component has a value is prepared for an appropriate number of gradations. ing.

In the LUT creation process shown in FIG. 3, the operator sets L to the image processing unit 100 via the operation unit 600.
After giving an instruction to create a UT, first, step S8.
1, the CMY pattern shown in FIG.
Read by 0. Here, the obtained RGB signal is S-
RGB. This makes it possible to create the first LUT 51 that associates the CMY halftone dot area ratio in the CMY pattern shown in FIG. 4 with the S-RGB value in step S82. By creating the first LUT 51, it is possible to obtain corresponding RGB signal values when the scanner 500 captures a printed matter printed with an arbitrary CMY halftone dot area ratio.

Next, consider the signal value that can be displayed on the display unit 200. Since the display unit 200 is a color monitor, the output signal format is RGB format.
The RGB format that can be output on the display unit 200 is P-RG.
Let B. The P-RGB depends on the display unit 200 and is known by its specifications and the like. Therefore, in step S83, it is possible to create the second LUT 52 that associates S-RGB and P-RGB described above. The second LUT 52 enables the display unit 200 to output the same tint as the original read by the scanner 500.

First LU created as described above
The value of P-RGB can be obtained from the value of the CMY halftone dot area ratio by T51 and the second LUT 52. Therefore, in step S84, the CMY halftone dot area ratio and P-RGB
It is possible to create a third LUT 53 that correlates with.

First LUT 5 created as described above
The relationship among the first, second LUT 52, and third LUT 53 is shown in FIG. That is, the first LUT 51 corresponds to CMY and S-RGB, the second LUT 52 corresponds to S-RGB and P-RGB, and the third LUT 53 corresponds to P-RGB and CMY.

First LUT 51, second LUT 52, third L
If the UT 53 is created, then in step S85, the K pattern shown in FIG.
Read at. Then, in step S86, the read RGB signal of the K pattern is input to the second LUT as S-RGB. S-RG input to the second LUT
B is converted to P-RGB and then input to the third LUT. Then, it is converted into a CMY signal.

Then, in step S87, the CMY values thus obtained are assumed to be the amounts of ΔC, ΔM and ΔY with respect to the K component shown in FIG.

Next, in step S88, K shown in FIG.
Fourth LUT that associates component values with ΔC, ΔM, and ΔY
54 is created. The fourth LUT 54 is the distribution processing unit 2
Referenced at 0.

Each LUT in the LUT unit 50 is generated as described above.

In the distribution processing section 20, the input K signal is distributed into ΔC, ΔM, and ΔY by the fourth LUT 54 created as described above. Then, the output ΔC, ΔM, and ΔY are C, M, and
It is input to the addition processing unit 30 together with the Y signal.

FIG. 7 shows a circuit configuration diagram in the addition processing section 30. In FIG. 7, 501, 502, and 503 are adders. The adder 501 adds C and ΔC to obtain C ′, and the adder 502 adds M and ΔM to obtain M ′.
The adder 503 adds Y and ΔY and outputs Y ′.

C ′ output from the addition processing unit 30,
The M ′ and Y ′ signals are input to the conversion processing unit 40. In the conversion processing unit 40, the P-RGB signal, that is, the color reproducibility of the display unit 200 is considered by referring to the third LUT 53 in the LUT unit 50 for the input C ′, M ′, Y ′ signals. Output RGB format image signal.

The RGB image signals output from the conversion processing unit 40 in this manner are displayed and output on the display unit 200.

As described above, according to this embodiment, the RGB signals displayed on the display section 200 are the CMY signals that are input.
Created by conversion that appropriately reflects the K component of the K signal,
Moreover, since the characteristics of the display unit 200 are taken into consideration, the same C
It is possible to display an image whose color tone is almost the same as the print result obtained when the MYK signals are offset-printed.

In this embodiment, each LUT is replaced by an LUT.
Although the description has been given assuming that the distribution is held in the unit 50, the present invention is not limited to this example, and the fourth LUT 54 may be held in the distribution processing unit 20, for example. Also, the third LUT
Similarly, 53 may be held in the conversion processing unit 40.

Further, although the third LUT 53 and the fourth LUT 54 are actually referred to in the LUT unit 50, by retaining the first LUT 51 and the second LUT 52, for example, when it is desired to change only a part of the tint. Etc. can be easily accommodated. If it is not necessary to consider the change of the LUT unit 50, the LUT unit 50 may be composed of a ROM.

In the above-described embodiment, an example has been described in which the RGB signals converted by the image processing unit 100 are displayed on the display unit 200, but of course they may be output to the printing unit 300. The printing unit 300 receives the RGB signals output from the image processing unit 100 and prints them out on a recording medium to form an image having a color tone equivalent to that of offset printing. Since the printed matter output from the printing unit 300 can be sufficiently utilized as a master plate in offset printing due to its color reproducibility, the system configuration to which the image processing apparatus of the present invention is applied is a color plate making system for offset printing. Is also applicable.

The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device. Further, it goes without saying that the present invention can be applied to the case where it is achieved by supplying a program to a system or an apparatus.

[0060]

As described above, according to the present invention, C
The CMYK image signal corresponding to the MYK halftone dot area ratio is input, and the K component is distributed to each CMY component in consideration of the undercolor removal (UCR) in offset printing and the color reproducibility of the image output unit. By converting the CMY components into RGB signals in consideration of the color reproducibility of the image output unit, undercolor removal (UC) in offset printing with respect to the input signal is performed.
R) and the color reproducibility difference in the image output unit can be taken into consideration, so that the image output unit can output an image with a tint almost similar to the tint output by offset printing.

Further, even when a part of the output tint is changed, only the corresponding data in the LUT needs to be changed, which can be easily performed.

[0062]

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a color image processing system that is an embodiment of the present invention.

FIG. 2 is a block diagram showing a detailed configuration of an image processing unit 100 in this embodiment.

FIG. 3 is a flowchart showing LUT generation processing in this embodiment.

FIG. 4 is a diagram showing a CMY pattern image in the present embodiment.

FIG. 5 is a diagram showing a K pattern image in the present embodiment.

FIG. 6 is a diagram showing a relationship among LUTs in this embodiment.

FIG. 7 is a circuit diagram showing a detailed configuration of an addition processing unit 30 in the present embodiment.

[Explanation of symbols]

 10 image memory 20 distribution processing unit 30 addition processing unit 40 conversion processing unit 50 LUT unit 51 first LUT 52 second LUT 53 third LUT 54 fourth LUT 60 CPU 61 ROM 62 RAM 100 image processing unit 200 display unit 300 printing unit 400 host computer 500 Image input unit 600 Operation unit

Claims (23)

[Claims] 1. Input means for inputting a color image signal of a first format, and a distribution amount for determining a distribution amount for distributing a black component of the color image signal of the first format to color components other than black in the first format. Determining means; adding means for adding the distribution amount to color components other than black of the first format color image signal; and color components other than black of the first format color image signal added by the adding means The distribution amount determining means and the output means for outputting the color image signal of the second format converted by the conversion means, and the converting means for converting the color image signal of the second format different from the first format. The image processing apparatus, wherein the conversion means determines the distribution amount and converts into the second format based on the color reproducibility of the output means. 2. The image processing apparatus according to claim 1, wherein the first format is a density expression in CMYK and the second format is a brightness expression in RGB. 3. The image processing apparatus according to claim 2, wherein the first format is a CMYK density expression corresponding to a halftone dot area ratio in offset printing. 4. The image processing apparatus according to claim 1, wherein the output unit displays and outputs the color image signal of the second format. 5. The image processing apparatus according to claim 1, wherein the output unit prints out the color image signal of the second format. 6. The image processing apparatus according to claim 3, wherein the distribution amount determination means determines the distribution amount by referring to a table. 7. The table reads a pattern image composed of CMY components by offset printing as an RGB signal, and reads the RGB signal and the CM.
Create a first table that associates Y components with the RG
A second table in which the B signal and the RGB signal that can be processed by the output means are associated with each other is created, the first table and the second table are combined to create a third table, and the K component by offset printing is created. A table created by reading a pattern image composed of R, G, and B signals, converting the RGB signals into CMY signals by referring to the second table and the third table, and correlating the K component with the CMY signals. The image processing apparatus according to claim 6, wherein the image processing apparatus is provided. 8. The image processing apparatus according to claim 7, wherein the conversion unit performs conversion by referring to a table. 9. The image processing apparatus according to claim 8, wherein the tables are the first table and the second table. 10. The image processing apparatus according to claim 8, wherein the table is the third table. 11. The image processing according to claim 7, wherein the pattern image including the CMY component and the pattern image including the K component have a plurality of gradations for each component. apparatus. 12. An input step of inputting a color image signal of a first format, and a distribution amount for determining a distribution amount for distributing a black component of the color image signal of the first format to a color component other than black in the first format. A determining step; an adding step of adding the distribution amount to a color component other than black of the color image signal of the first format; and a color component other than black of the color image signal of the first format added by the adding step. A conversion step of converting into a color image signal of a second format different from the first format; and an output step of outputting the color image signal of the second format converted by the conversion step. In the conversion step, the image processing method is characterized in that the distribution amount is determined and conversion into the second format is performed based on the color reproducibility in the output step. 13. The image processing method according to claim 12, wherein the first format is a density expression by CMYK, and the second format is a brightness expression by RGB. 14. The image processing method according to claim 13, wherein the first format is a CMYK density expression corresponding to a halftone dot area ratio in offset printing. 15. The image processing method according to claim 12, wherein in the output step, the color image signal of the second format is output for display. 16. The image processing method according to claim 12, wherein the color image signal of the second format is printed out in the output step. 17. The image processing method according to claim 14, wherein in the distribution amount determining step, the distribution amount is determined with reference to a table. 18. The table reads a pattern image composed of CMY components by offset printing as an RGB signal, and reads the RGB signal and the CM.
Create a first table that associates Y components with the RG
A second table in which the B signal and the RGB signal that can be processed by the output means are associated with each other is created, the first table and the second table are combined to create a third table, and the K component by offset printing is created. A table created by reading a pattern image composed of R, G, and B signals, converting the RGB signals into CMY signals by referring to the second table and the third table, and correlating the K component with the CMY signals. 18. The image processing method according to claim 17, wherein the image processing method is provided. 19. The image processing method according to claim 18, wherein in the converting step, conversion is performed by referring to a table. 20. The image processing method according to claim 19, wherein the tables are the first table and the second table. 21. The image processing method according to claim 19, wherein the table is the third table. 22. The pattern image composed of the CMY components and the pattern image composed of the K components have a plurality of gradations for each component.
The image processing method according to any one of 1. 23. Input means for inputting a color image signal of a first format, and a distribution amount for determining a distribution amount for distributing a black component of the color image signal of the first format to color components other than black in the first format. Deciding means; adding means for adding the distribution amount to color components other than black of the first format color image signal; and color components other than black of the first format color image signal added by the adding means The distribution amount determining means and the output means for outputting the color image signal of the second format converted by the conversion means. The image processing system, wherein the conversion means determines the distribution amount and converts into the second format based on the color reproducibility of the output means.