JPH10210312A - Color converter, color conversion method and medium with color conversion program recorded - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the color reproducibility precise as to at least a specific color, without deteriorating the overall color tone. SOLUTION: In the case that an image such as a corporate mark 53 is fully reproduced by the capability of a color printer 60, a patch which watch the mark selected from among printed color patches is selected to make color data corresponding to the selected path. Then in the case of color conversion by a color conversion section 31b2 of a PC main body 30, whether or not color data of an object pixel are specific color data is discriminated in a step S301 and normal color conversion processing is executed in the step S320, when the data are not the specific color data. The data are converted into color data found out in the step S330 when data the specific color data, so as to make the color matching with that of the corporate mark 53 in which strict color reproducibility is a requirement, when the mark is finally printed out on paper.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color conversion device, a color conversion method, and a medium on which a color conversion program is recorded.

[0002]

2. Description of the Related Art In a color printer or the like that performs color printing based on predetermined color data, there is a demand to accurately reproduce colors. However, at present, due to various factors, it is not always possible to reach a level that satisfies the reproducibility of all colors.

[0003] On the other hand, there is a demand not only to require reproducibility of all colors but also to reproduce only specific colors such as corporate marks. In such a case, if the specific color is a color that can be reproduced by a color printer, it is possible to print the mark portion in the corporate color by changing the color tone of the image data.

[0004]

In the above-described conventional color conversion apparatus, it is not impossible to accurately reproduce a specific color portion such as a corporate color, but other portions also have a similar color tone. There has been a problem that the color tone can be changed, resulting in a poor overall color tone.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a color conversion apparatus and a color conversion apparatus capable of accurately improving color reproducibility of at least a specific color without deteriorating the overall color tone. It is an object of the present invention to provide a method and a medium recording a color conversion program.

[0006]

According to a first aspect of the present invention, there is provided a color conversion apparatus for converting color data between different colorimetric spaces in a predetermined correspondence relationship. A main color conversion means for storing a relationship and inputting color data in one color space and converting it into color data in another color space, and a correspondence different from the above correspondence for specific color data on the input side And a specific color conversion means for performing color conversion into predetermined color data in a related manner.

In the invention according to claim 1 configured as described above, when converting color data between different color space in a predetermined correspondence relationship, the main color conversion means stores the correspondence relationship. , And converts color data in one color space on the input side into color data in another color space on the output side. However, it also has specific color conversion means,
The specific color conversion means converts the specific color data into predetermined color data in a correspondence different from the above correspondence. Therefore, the specific color data is not converted in the normal correspondence by the main color conversion means, but is converted in a different correspondence.

[0008] As an example of a situation in which such a normal correspondence color conversion needs to be performed in parallel with a different correspondence relationship, the invention according to claim 2 is based on the color conversion described in claim 1. In the apparatus, the specific color conversion means is configured to perform color conversion so that the specific color on the input side matches the color of the final output result.

In other words, despite the fact that the normal correspondence shows a match as the color data, the final output result often does not have the desired color depending on hardware conditions, etc. According to the second aspect of the present invention, the specific color conversion means dare converts the specific color in a correspondence different from the normal correspondence, so that the colors of the final output result do not match as color data but do not match. Will do.

Of course, in addition to matching the final output result, it is also possible to change the color in order to improve the taste of the specific color.
It can be said that the matching of the final output result is only one mode.

There are various modes of color conversion between colorimetric spaces in which the main color conversion means is implemented. For example, cyan color for printing red, green and blue (RGB) color data to be displayed on a display or the like on a color printer. -The color data of magenta yellow black (CMYK) is converted, or the color data of the same red, green, blue (RGB) is used to match the color of the scanner with the color of the display. It changes the gradation of red, green, blue (RGB) color data, or converts cyan, magenta, yellow (CMY) color data to cyan, magenta, yellow, black (CMYK) color data. It is not particularly limited.

As a simplest example of performing a special color conversion on specific color data while performing a general color conversion, the invention according to a third aspect is the invention according to any one of the first and second aspects. In the color conversion device, when the input color data is the specific color data, the specific color conversion unit converts the input color data into the color data having the predetermined correspondence, and the input color data is When the color data is not specific color data, the main color conversion means performs color conversion in the predetermined correspondence.

According to a third aspect of the present invention, as described above, the specific color conversion means first determines whether or not the color data is the specific color data. The means performs normal color conversion, and specific color data is converted according to another color conversion correspondence. That is, the method of color conversion is made different depending on whether the data is specific color data.

Various methods can be used for such color conversion, and a color conversion table can be used. Here, as an example of efficiently using the same color conversion table, the invention according to claim 4 is the color conversion device according to claim 1 or 2, wherein the main color conversion means is configured to be an input side. And a conversion table for the correspondence between the output and the color data on the output side, and the specific color conversion means is configured to rewrite the contents of the conversion table.

According to the fourth aspect of the present invention, there is provided a conversion table for the correspondence between the color data on the input side and the output side, and the main color conversion means uses the color data of the conversion source. The color conversion is performed by referring to the conversion table and the stored color data. However, the specific color conversion unit rewrites the contents of the conversion table so that the specific color has the different correspondence, and the main color conversion unit refers to the conversion table for the specific color and reads it out as usual. For example, the color data itself is already the color data of a desired correspondence.

That is, by preparing one standard color conversion table and rewriting a part of the table for specific color data, a common color conversion table can be used without any change in processing during color conversion. A conversion will be performed.

By the way, color data is provided only for grid points in the color space, and color data located between grid points is subjected to color conversion by interpolation or the like. Can not save the corresponding data. In such a case, the specific color should be treated in the same way as grid points, and
What is necessary is just to avoid interpolation calculation as what matched the grid point.

In these methods, it is possible to refer to individually prepared color data for specific color data. However, it is also possible to change the correspondence for specific color data while always adopting the same color conversion. As one example, the invention according to claim 5 is characterized in that, in the color conversion device according to claim 1 or 2, the specific color conversion unit converts the specific color data in advance. And a pre-conversion processing means for obtaining desired color data after the conversion by the main color conversion means.

As a result of normal color conversion of some color data, a desired color corresponding to specific color data may be obtained. In the invention according to claim 4 configured as described above, the pre-conversion processing unit of the specific color conversion unit converts the specific color data into another color data as described above in advance. Therefore, when the main color conversion means performs color conversion using this color data, the color data becomes desired color data corresponding to the specific color data.

On the other hand, as an example in which the same concept is applied to the output side, the invention according to claim 6 is a color conversion device according to any one of claims 1 and 2, wherein the specific color conversion means is And a post-conversion processing unit for converting the color data resulting from the conversion of the specific color data by the main color conversion unit into desired color data.

That is, although the color conversion is performed for all the color data as usual, if the obtained color data corresponds to the above-mentioned specific color data, the specific color conversion means of the specific color conversion means may become the desired color data. The post-conversion processing means performs color conversion.

On the other hand, the color data to be made to correspond to such specific color data can be selected by trial and error, but it becomes extremely difficult as the number of colors increases. In order to cope with such a situation, the invention according to claim 7 is a color conversion apparatus according to any one of claims 1 to 6, wherein the reference color and the reference color are slightly different from each other. And a similar color output means for outputting a plurality of output colors, and accepting an input of selection for the plurality of output colors and associating the information of the same reference color with the specific color data on the input side if the selection means a reference color. If the selection means a color other than the reference color, the image processing apparatus is provided with a correspondence forming means for instructing the similar output means to use the selected color as the reference color.

In the invention according to claim 7 configured as described above, the similar color output means outputs an arbitrary reference color and a slightly different color with respect to the same reference color, and one of them is output by the correspondence forming means. Select output color. put it here,
Until the desired color is output, the most similar color is selected. Then, the correspondence forming unit instructs the similar color output unit to use the color as a reference color.
The similar color output means outputs slightly different colors using the selected color as a reference color. On the other hand, when the desired color is finally output as the reference color among the plurality of output colors, when the same reference color is selected, the correspondence forming unit specifies the information of the same reference color as the input side. Color data.

That is, if the most similar one is selected from the output ones, the desired color is finally reached, so that the reference color information at that time is associated with specific color data. Of course, the input in the correspondence forming means can be appropriately executed using various input devices such as a keyboard and a mouse. On the other hand, when the similar color output means outputs colors slightly different from the reference colors, it is necessary to finally reach a desired color. Therefore, the degree to which the reference color is slightly different from the reference color may be changed at the time of selection or the like. Further, the operation side may positively designate the color component of the reference color.

Here, since the color space cannot be grasped as a plane, it is necessary to devise to display a plurality of colors so as to reach a desired color. As an example, the invention according to claim 8 is as follows. In the color conversion device according to the seventh aspect, the similar color output means is configured to perform substantially three-dimensional display in which two-dimensional display is output on a plurality of planes so that hue and lightness are different from each other.

In the invention according to claim 8 configured as described above, by outputting two-dimensional display on a plurality of planes, substantially three-dimensional display combining hue and brightness can be performed. For example, one two-dimensional display is a display with a different hue for a certain brightness, and if such a two-dimensional display is slightly changed in brightness and prepared on multiple surfaces, it is possible to follow at least a three-dimensional color space Become.

Further, according to the ninth aspect of the present invention, when converting color data between different color spaces in a predetermined correspondence relationship, the color data in one color space is normally converted in accordance with the correspondence relationship. The input color is converted into color data in another color space, and specific color data is color-converted into predetermined color data in a correspondence different from the above correspondence.

That is, there is no difference in that the present invention is not necessarily limited to a substantial device but is also effective as a method.

By the way, such a color conversion device and a color conversion method may exist alone or may be used in a state of being incorporated in a certain device. Is included. Also, it may be software or hardware,
It can be changed as appropriate.

As an example, a printer driver that converts color data in a color space different from a color space corresponding to printing ink in a predetermined correspondence relationship stores the above correspondence relationship and stores the same in another color space. Main color conversion means for inputting color data in a space and converting the color data into color data in a color space corresponding to the printing ink; A configuration may also be provided that includes a specific color conversion unit that performs color conversion into data.

That is, the printer driver converts color data of a different color space in a color space corresponding to the printing ink in a predetermined correspondence relationship. The color data in the color space is input and converted into the color data in the color space corresponding to the printing ink. For the specific color data on the input side, the specific color conversion means is different from the above correspondence. Then, the color is converted into predetermined color data, and printing is performed based on the same color data.

In particular, in a printing apparatus for printing on a paper surface or the like as a final output, the feeling of color changes very easily depending on the paper quality and paper color. In such a case, although a general image does not matter much, a specific color such as a corporate color is particularly likely to be dissatisfied.
On the other hand, the reproducibility of such a specific color is improved only by the printer driver, so that no complaint occurs.

In the case where the software of the color conversion device is used as an embodiment of the idea of the present invention, the software naturally exists on a recording medium on which such software is recorded, and it must be said that the software is used.

As one example, the invention according to claim 10 is a medium in which a program for performing color conversion by a computer is recorded, and when color data is converted in a predetermined correspondence relationship between different color specification spaces, usually In accordance with the correspondence, color data in one color space is input and converted into color data in another color space,
The specific color data is configured to be color-converted into predetermined color data in a correspondence different from the above correspondence.

Of course, the recording medium may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium to be developed in the future. Also, the duplication stages of the primary duplicated product, the secondary duplicated product, and the like are equivalent without any question. In addition, in the case of software, the supply method is not provided as the above-described recording medium, but the present invention is used even when provided using a communication line.

Further, even when a part is implemented by software and a part is implemented by hardware, there is no difference in the concept of the invention, and it is necessary to store a part on a recording medium. It may be in a form that is appropriately read in accordance with it. Further, it goes without saying that the present invention can be applied to a color facsimile machine and a color copier.

[0037]

As described above, the present invention provides a color conversion apparatus which can make the correspondence of a specific color different from the normal correspondence and can improve various kinds of taste. be able to.

According to the second aspect of the present invention, the final output color of a specific color can be made to coincide with the original color. Therefore, when strict color matching is required, it is simple and effective. Color conversion.

Further, according to the invention of claim 3,
First, it is determined whether the data is the specific data, and the processing is changed depending on the specific color data and the other color data. Therefore, a simple configuration can be achieved, and maintenance and change can be easily performed.

Further, according to the invention according to claim 4,
By rewriting the contents of the conversion table in advance, the color conversion work itself becomes common, and the processing can be performed at high speed.

Further, according to the invention of claim 5,
By changing the specific color data in advance, this can be realized without changing the normal color conversion processing.

Further, according to the invention of claim 6,
Since only the color data corresponding to the specific color data is changed after the normal color conversion processing is performed, it can be realized without changing the normal color conversion processing.

Furthermore, according to the invention of claim 7,
Since a desired color can be obtained by a selection operation from similar output colors, the operation is facilitated.

Further, according to the invention of claim 8,
It is possible to display a similar color without omission, and the operator can follow this to reach a desired color.

Further, according to the ninth aspect of the present invention, the correspondence for a specific color can be made different from the normal correspondence, so that various tastes can be improved,
A color conversion method capable of matching the final output color with the original color can be provided.

According to the tenth aspect of the present invention, it is possible to provide a medium in which a program for performing such color conversion is recorded.

[0047]

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

FIG. 1 shows the concept of a color conversion apparatus according to an embodiment of the present invention, and FIG. 2 shows a specific configuration example by a block diagram.

As shown in FIG. 1, the color conversion apparatus 1 of the present invention
In 0, at least a main color conversion unit 11 and a specific color conversion unit 12 are provided, and the same color conversion device 10 receives input color data, performs predetermined color conversion, and outputs it as output color data. Here, the main color conversion unit 11 and the specific color conversion unit 12 perform color conversion in cooperation with each other, and perform color conversion for matching colors other than the specific color as color data.
The specific color is converted so that the actual color of the input color data matches the color as the final output result.

More specifically, the color conversion device 10 comprises a computer system 20 shown in FIG. The computer system 20 includes a PC body 30
, A scanner 40 as an image input device, a display 50 as an image output device, and a color printer 60 also as an image output device. Note that a keyboard and a mouse (not shown) are connected to the PC main body 30 so that various input operations can be executed.

A not-shown CPU or R
An OM, a RAM, and the like are provided, and an operating system 31 serving as a basic program is operated, and an application 32 can be executed on the operating system 31. Here, the display on the display 50 and the printing by the color printer 60 are performed in conjunction with the execution of the application 32, and the color image data at this time is stored in the operating system 31.
Are output to the display 50 and the color printer 60 via a predetermined interface circuit via a video driver 31a and a printer driver 31b incorporated in the printer.

In the PC body 30, the scanner 40, and the display 50, a color image is converted into red, green, blue (RG
Each component B) is treated as gradation color data represented by gradation data. However, in the color printer 60, cyan, magenta, yellow (CM
Each component Y) is treated as gradation color data represented by gradation data. Therefore, when the color printing is finally performed by the color printer 60 after the processing for handling the color image is performed by the PC body 30, the RGB gradation color data is converted to the CMY color data.
It is necessary to convert the data into gradation color data, and the color conversion unit 31b2 in the printer driver 31b performs such color conversion. The printer driver 31b includes a rasterizer 31b1 for cutting out data corresponding to the scan range of the print head from the color image data, and the color conversion unit 31b2.
And a halftone module 31b3 for binarizing the CMY gradation color data. That is, it can be said that such a color conversion unit 31b2 constitutes the color conversion device 10 in the present embodiment. Such a color conversion unit 31b2 is constituted by a color conversion program, and when recording the same color conversion program, as shown in FIG.
A portable medium such as 42 is of course installed in the hard disk 43,
It may be an IC card having a ROM 44 or a RAM 45, or a communication line 46a via a modem 46b or the like.
Can be used as a medium.

In the present embodiment, the entire process from input to output is performed as the computer system 20 centered on the PC body 30, but the present invention is applicable as long as there is at least a color conversion process. For example, if an image captured by a digital still camera or the like is normally stored as RGB gradation color data, but it can be output as CMY gradation color data when directly connected to a color printer. Performs color conversion, and is also applicable to color printing of a color image on a television having a network terminal function.

An example in which a document is created and printed in the computer system 20 will be described. FIG.
Of the document being created is displayed in the display 50 of. Here, it is assumed that the document includes a descriptive character portion 51 input by a keyboard, a photographic image portion 52 obtained by capturing a photographic image by the scanner 40, and a corporate mark portion 53 for general use. At least the photographic image portion 52 and the corporate mark portion 53 are composed of color image data, and the corporate mark portion 53
It is assumed that the color designation is strict, and the corporate mark portion 53 is stored as bitmap data in a hard disk (not shown).

When a document including such a color image or the like is to be printed by the color printer 60, the above-described color conversion from the RGB color space to the CMY color space is performed. Although the color space is originally one, how to represent it differs depending on how to take the coordinates. Therefore, the color data when a certain color is represented by the RGB coordinate axes is CMY
Even if the coordinates are expressed by the coordinate axes, the colors match each other. By the way, the correspondence between the color specification spaces in such a case is not represented by a uniform conversion formula,
Originally, there is no other way but to find and record the correspondence between all the coordinates. In the present embodiment, such a theoretical color conversion between color spaces is referred to as a main color conversion.

However, as the number of gradations of each component increases, the number of colors that can be expressed increases in proportion to the cube of the number. Therefore, it is impractical to prepare a conversion table. This is because, for example, if “256” gradation is used for one color, about 16.7 million colors are used for three colors of RGB. To simply associate each color of CMY from the three elements of RGB, an array variable of “16.7 million × 3” is required. For this reason, in the main color conversion, instead of preparing a conversion table for all colors corresponding to all gradations, as shown in FIG. 3, grid points storing correspondences between discrete grid points on coordinate axes of three colors as shown in FIG. A conversion table is prepared, and the main color conversion can be executed by a color conversion method using interpolation or gradation conversion. FIG. 4 shows the relationship between the gradation and the lattice points, and in the present embodiment, “0 to 2”.
A total of 256 gradations of “55” are approximately equally divided for every 32 gradations to obtain “9” grid points, which is a grid point conversion table having an array of “9 × 9 × 9 = 279” elements. .

In the interpolation calculation, the correspondence of the coordinates of the coordinates of the coordinates on the RGB coordinate axes is obtained through the operation of linear interpolation using the correspondence of the lattice points surrounding the coordinates. FIGS. 5A to 5C show the concept of eight-point interpolation, which is an example of such linear interpolation. The conversion source color space is divided into a unit cubic grid, and the corresponding values of the conversion destination at the grid points are separately obtained. Assuming that the converted value at the k-th vertex Pk of the cube is Xk = [ck, mk, yk] and the volume of the cube is V, the corresponding value at the inner point P of the cube is divided at point P in the figure. Eight small rectangular parallelepiped volumes V
Interpolation can be performed by the following equation based on the weight according to the ratio of k.

[0058]

(Equation 1)

Therefore, when the main color conversion is performed, first, as shown in FIG. 6, it is determined to which grid section the coordinate position P (Rx, Gx, Bx) on the RGB coordinate axis of the pixel to be color-converted belongs. Calculation (step S110), then read out a table for the eight surrounding grid points (step S120), calculate the volume ratios of the eight rectangular parallelepipeds subdivided at the coordinate position P (step S130), and finally, for each color Are multiplied by the volume ratio and integrated (step S140), the interpolation calculation is completed, and color data on the CMY coordinate axes can be obtained.

In the present embodiment, such an interpolation operation is executed in the main color conversion. However, in FIG. 7 and FIG. 8, color conversion by gradation conversion may be executed instead of such interpolation operation. . Eight multiplications and seven additions are required in the interpolation operation, and the burden of resources and time is large regardless of whether hardware is used or software is used. The color conversion by the gradation conversion is to perform the color conversion more easily, and a specific method thereof is shown in FIGS. 7 and 8.

FIG. 7 shows a flowchart, and FIG.
Indicates an error distribution of pixels used in the method. Find the nearest grid coordinates for the target pixel (step S
210), an error (dg) from the grid coordinates is calculated (step S220), and the error (dg) is distributed to neighboring pixels (step S230). Therefore, even if the color is not converted into the same color for each pixel, the color components including the peripheral pixels are securely stored, and the load of calculation can be reduced as compared with the case where multiplication and addition are repeated while performing good color conversion. .

In the present embodiment, the color conversion is performed by the above-described interpolation calculation and gradation conversion. However, it is needless to say that other methods can be adopted.

In this way, despite the conversion between the color spaces that originally match, the color printer 60
When printing on paper, the colors do not always match. This is because printing on paper easily changes its color depending on paper quality and the like. In the case of printing the above-described document, the reproducibility of the color of the description character portion 51 is not so important, and the photographic image portion 52 and the corporate mark portion 53 are essentially required. However, at present, since accurate color reproducibility cannot be realized in the photographic image portion 52, it has to be given up. However, only a specific color such as the corporate mark portion 53 can be reproduced as long as the color can be printed by the color printer 60.

For this reason, in the color conversion performed by the color conversion section 31b2 in the printer driver 31b, as shown in FIG. 9, it is determined in step S310 whether the color data of the pixel to be converted is specific color data. If it is not specific color data, the main color conversion processing including the above-described processing is executed in step S320. If it is specific color data, the main color conversion is not performed but the above-described main color conversion is performed in step S330. The specific color data conversion process is performed.

In the specific color data conversion processing, when the specific color data is input, the color data (C ′, M ′,
Y ′). This relationship is shown in FIG.

Here, a method for obtaining such another color data will be described. 11 and 12 show a process of printing a slightly different color around a certain reference color in the form of a patch and repeating the operation of bringing a similar color to the center to arrive at a desired color. Is shown.

As shown in FIG. 11, first, in step S4
In 10, the starting color to be placed at the center position is determined first, but usually, color data obtained by main color conversion based on specific color data may be used. Subsequent step S4
In FIG. 20, the center color is used as the center and 5 as shown in FIG.
Print color patches in a × 5 grid. In this example,
A color patch having the same lightness as the center color but a different hue is printed, and the a + axis and the b + axis are made to coincide with the horizontal axis and the vertical axis on the paper based on the L * a * b standard color system. The hue (a, b) is slightly different from the center color. That is, printing is performed by changing only the value of “a” in the horizontal direction and changing only the value of “b” in the vertical direction, and the amount of change is proportional to the distance from the center color. The amount of change is such that a color difference of ΔE is obtained for a patch in contact with the outer periphery of the center color, and a color difference of ΔE × 2 is obtained for other color patches. That is, in FIG. 12, “7, 8, 9, 12, 14, 17, 18, 1” around the reference color is used.
The patch “9” has a color difference of ΔE, and the other patches have a color difference of ΔE × 2.

In step S430, the process waits for an input to determine whether or not the center color in the color patch set in this manner matches the color sample of the corporate color. If you change the center color little by little as described later,
Eventually, the center color will match the sample color,
If "YES" is input, the color data of the center color is written in the specific color data conversion table in step S460 as conversion data for the specific color data.

However, if the center color does not match the color sample, step S440 is executed, and step S4 is executed.
At 40, the process waits for the input of the closest color in the color patch. Then, when the color closest to the color sample among the color patches is input, the color is set as the center color in step S450, and the process shifts to printing of the color patch in step S420. In this way, the center color gradually matches the sample color while selecting a similar color.

In the present embodiment, similar color patches are printed by changing only the hue. However, the color space includes elements that are difficult only by such two-dimensional display. Therefore, when printing a color patch, it is possible to print a three-sided color patch with slightly changed brightness as shown in FIG. In the example shown in the figure, FIG. 6B shows a color patch having the same brightness as the original center color and slightly different hues in the horizontal direction and the vertical direction. In FIG. 10C, the color patches are printed based on the same standard by increasing the brightness of the center color while decreasing the brightness of the center color. As in this example, by outputting the two-dimensional display on a plurality of planes by making the hue and the brightness different from each other, substantially three-dimensional display becomes possible, and in the color space, it is possible to reliably reach the desired color. Become.

In the present embodiment, the process of step S420 for printing a color patch corresponds to similar color output means, and changes the center color in steps S440 and S440.
The processing of S450 and the processing of steps S430 and S460 in which the data of the center color is associated with the specific color data when the center color matches the sample color correspond to the correspondence forming means.

In the present embodiment, such color patches are printed in order to convert the RGB gradation color data into the CMY gradation color data. The same color patch may be displayed or selected on 50.

As described above, the color data corresponding to the specific color data is obtained, and if the result is written in the specific color data conversion table as shown in FIG. If the color data is the specific color data, the specific color data conversion process of step S330 is executed, and the corresponding color data is read from the specific color data conversion table and converted. Then, in step S340, the target pixel is moved to the next pixel,
The color data of each pixel is sequentially converted until it is determined that the pixel is the last pixel in step S350.

In the case of the above document, the color data of the corporate mark portion 53 is treated as specific color data in the case of the above document, so that the descriptive character portion 51 and the photographic image portion 52 are processed.
Are converted by the main color conversion process, and the pixels of the corporate mark portion 53 are converted by the specific color data conversion process.

However, such main color conversion processing and specific color data conversion processing do not necessarily need to be separately separated in this way.

For example, FIG. 14 shows a modification of the present invention, which corresponds to the conversion of specific color data by rewriting the conversion table used in the above-described main color conversion processing. In this example, it is determined whether or not a correspondence has been formed in step S510, and if no correspondence has been formed, color data that should correspond to the specific color data is found through the above-described processing in step S520. . Then, the conversion table to be used in the main color conversion processing is rewritten with the found color data. That is, the color data found in step S520 is written as the color data to be read when referred to by specific color data.

By doing so, the process of step S54 is performed without concern for the color data of each pixel.
The color conversion is performed by the main color conversion process of 0. However, when the main color conversion processing is performed on the specific color data, the read data is the rewritten color data. Then, step S5
At 50, the target pixel is updated, and the process is repeated until it is determined at step S560 that the pixel is the last pixel.

Further, the modified examples shown in FIGS. 15 and 16 show an example in which the main color conversion is similarly performed for all the pixels without changing the data of the conversion table.

In the modification shown in FIG. 15, when the main color conversion processing is executed based on another color data different from the specific color data, the same color conversion as the sample color may be executed. Before executing the main color conversion process in step S630, it is determined in step S610 whether or not the color data is specific color data. A pre-conversion process is performed to convert the color data into another color data that matches. Therefore, if the color data is specific color data, the main color conversion processing will be executed with the color data changed in the pre-conversion processing. Is converted. Steps S640 and S650
The process of shifting pixels until the pixel becomes the last pixel is the same. Of course, the correspondence in this case can be obtained by using the original data of the color patch to be printed as shown in FIG.

On the other hand, in the modification shown in FIG. 16, the main color conversion processing is executed for the time being in step S710, and it is determined in step S720 whether or not the result of the main color conversion is for the specific color data. . Since only one color data is obtained when the primary color conversion is performed for the specific color data, if it is determined in step S720 that such color data is obtained, a sample is obtained in the post-conversion processing in step S730. What is necessary is just to replace with the color data of a color.

Next, the operation of the present embodiment having the above configuration will be described.

The application 32 is executed by the PC main body 30, and the application 32 executes the description character portion 5.
1 and a photographic image portion 52 of the image read by the scanner 40 and a corporate mark portion 53 stored in a hard disk or the like are combined to create a document.

On the other hand, a sample color is separately prepared for the corporate mark portion 53, and the correspondence forming process shown in FIG. 11 is executed. That is, in step S4, a color patch matching the sample color is printed in step S420.
The selection of similar colors is repeated at 40, and when the center color matches the sample color, color data is written to the specific color data conversion table at step S460.

On the other hand, when the created document is printed, the printer driver 31b is activated via the operating system 31, and the color image data created by the application 32 is transferred. Printer driver 3
In 1b, first, the rasterizer 31b1 cuts out color image data that matches the scan range of the print head, and the color conversion unit 31b2 performs color conversion on the cut out color image data in pixel units.

This color conversion processing is shown in FIG. 9. In step S310, it is determined whether or not the color data of the target pixel is specific color data. If the extracted image data is the descriptive character portion 51 or the photographic image portion 52, it is determined that the image data is not specific color data unless there is a coincidence, and the main color conversion process is performed in step S320. The execution result of such a main color conversion process is stored in a predetermined buffer, and is stored in the next halftone module 31b.
3 after the halftone processing by the color printer 60
And printed in color on paper. The color of the final result printed on the paper is slightly deviated from the color seen on the display 50, but is generally acceptable.

However, the corporate mark part 5
In the case where the image data of No. 3 is cut out, when the same pixel is to be processed, it is determined in step S310 that the color data is the specific color data, and the specific color data conversion process is executed in step S330. In this specific color data conversion processing, the color data obtained in the previous correspondence formation processing is used as a color conversion result for the pixel and output to the predetermined buffer as described above. Then, the halftone module 31
When the data is output to the color printer 60 and printed after the halftone processing of b3, it matches the original corporate color.

As described above, under the present situation where it is desired to improve the color reproducibility of a photograph or the like, it cannot be realized.
In the case where the image data can be reproduced sufficiently with the capability of the PC, the matching color data is selected by selecting the matching color patches from the printed color patches, and the color conversion unit 31
When color conversion is performed in b2, it is determined in step S310 whether or not the color data of the target pixel is specific color data. If the color data is not specific color data, normal color conversion processing is performed in step S320. If the color data is specific color data, it is converted to the color data found in step S330, so that the color matching of the corporate mark portion 53 that requires strict color reproducibility when finally printed on paper is required. Can be seen.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the concept of a color conversion device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a computer system as a specific configuration example of the same color conversion apparatus.

FIG. 3 is a block diagram illustrating a concept of a main color conversion process.

FIG. 4 is a diagram illustrating a relationship between a gradation of gradation data and a grid point;

FIG. 5 is a diagram illustrating the concept of eight-point interpolation.

FIG. 6 is a flowchart illustrating a processing procedure of eight-point interpolation;

FIG. 7 is a flowchart illustrating a processing procedure of color conversion by gradation conversion.

FIG. 8 is a diagram showing a concept of error diffusion performed by color conversion by gradation conversion.

FIG. 9 is a flowchart illustrating a processing procedure of color conversion.

FIG. 10 is a block diagram illustrating a concept of a specific color data conversion process.

FIG. 11 is a flowchart of a correspondence forming process.

FIG. 12 is a diagram showing color patches printed in the correspondence forming process.

FIG. 13 is a diagram showing a substantially three-dimensional display color patch printed in the correspondence forming process.

FIG. 14 is a flowchart illustrating a color conversion processing procedure according to a modification.

FIG. 15 is a flowchart illustrating a color conversion processing procedure according to a modification.

FIG. 16 is a flowchart illustrating a color conversion processing procedure according to a modification.

FIG. 17 is a diagram showing a medium for recording a color conversion program.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Color conversion apparatus 12 ... Specific color conversion means 20 ... Computer system 30 ... PC main body 31 ... Operating system 31a ... Video driver 31b ... Printer driver 31b1 ... Rasterizer 31b2 ... Color conversion unit 31b3 ... Half tone module 32 ... Application 40 ... Scanner 41: Flexible disk 42: CD-ROM 43: Hard disk 44: ROM 45: RAM 46a: Communication line 46b: Modem 50: Display 51: Descriptive character part 52: Photographic image part 60: Color printer

Claims (10)

[Claims] 1. A color conversion device for converting color data between different color spaces in a predetermined correspondence relationship, wherein said correspondence relationship is stored and color data in one color space is input to another color space. Main color conversion means for converting color data into color data in a color specification space; and specific color conversion means for performing color conversion of specific color data on the input side into predetermined color data in a correspondence different from the above correspondence. A color conversion device characterized by the above-mentioned. 2. The color conversion apparatus according to claim 1, wherein the specific color conversion means performs the color conversion such that the specific color on the input side matches the color of the final output result. Color conversion device. 3. The color conversion device according to claim 1, wherein the specific color conversion unit includes:
When the input color data is the specific color data, the color conversion is performed to the color data having the predetermined correspondence, and when the input color data is not the specific color data, the main color conversion means is used. Wherein the color conversion is performed according to the predetermined correspondence. 4. The color conversion device according to claim 1, wherein said main color conversion means has a conversion table for a correspondence relationship between input side and output side color data. And a color conversion device, wherein the specific color conversion means rewrites the contents of the conversion table. 5. The color conversion device according to claim 1, wherein the specific color conversion unit includes:
A color conversion apparatus comprising: a pre-conversion processing unit that pre-converts the specific color data so as to obtain desired color data after the conversion by the main color conversion unit. 6. The color conversion device according to claim 1, wherein the specific color conversion unit includes:
A color conversion apparatus comprising: a post-conversion processing unit that converts color data obtained as a result of conversion of the specific color data by the main color conversion unit into desired color data. 7. The color conversion apparatus according to claim 1, wherein said similar color output means outputs a reference color and a slightly different color with respect to the same reference color. If the input of the selection for the output color is received and the selection means the reference color, the information of the reference color is associated with the specific color data on the input side and if the selection means other than the reference color A color conversion device comprising: a correspondence forming unit that instructs the similar output unit to use the selected color as a reference color. 8. A color conversion apparatus according to claim 7, wherein said similar color output means performs a substantially three-dimensional display in which a two-dimensional display is output on a plurality of planes so that hue and lightness are different from each other. A color conversion device characterized by the above-mentioned. 9. When color data is converted between different color spaces in a predetermined correspondence relationship, color data in one color space is normally input in accordance with the correspondence relationship to convert the color data into another color space. And converting the specific color data into predetermined color data in a correspondence different from the correspondence described above. 10. A medium in which a program for performing color conversion by a computer is recorded, and when converting color data between different color specification spaces in a predetermined correspondence relationship, normally, one table corresponding to the correspondence relationship is stored. Color data in a color space is input and converted into color data in another color space, and specific color data is color-converted to predetermined color data in a correspondence different from the above-described correspondence. A medium that stores a color conversion program.