JP2003162714A - Device and method for correcting color and medium with color correction control program recorded thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color correcting device and method capable of automatically executing optimal color correction processing with stored colors taken into consideration and a medium with a color correction control program recorded thereon. <P>SOLUTION: A computer 21 constituting the center of color correction calculates the x-y chromaticity of each pixel by a step S110, and when the chromaticity is within the possible range of the chromaticity of a skin color, the computer 21 totals those pixels by steps S120 and S130, and calculates the mean value of the totaled results of all the pixels by a step S160, and calculates color correction quantity with the number of pixels taken into consideration by a step S170. Thus, it is possible to accurately total the pixels of colors to be corrected without being affected by the brightness, and to execute the optimal color correction without substantially affecting the colors of the peripheral pixels by adjusting the correction quantity with the number of pixels taken into consideration. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color correction device, a color correction method, and a medium having a color correction control program recorded therein, which performs optimum color correction on real image data such as a digital photographic image.

[0002]

2. Description of the Related Art Various color correction processes are performed on digital image data. For example, it is a process of emphasizing or weakening each of the RGB element colors.
For the sake of convenience, the process of strengthening and the process of weakening are both referred to as emphasis processing. Usually, these processes can be executed by a microcomputer, and the operator checks the image on the monitor and selects the element color that needs to be corrected, while determining parameters such as the degree of emphasis.

[0003]

In recent years, color correction by image processing has become easy and has become widely used. However, when it comes to which element color and how much to emphasize, humans must still be involved.
This is because, in the digital image data that is the target of the color correction processing, it was not possible to determine where the portion where the color shift is noticeable was.

For example, in the case of the color of a building, the color shift is not known unless the original color is known. However, the skin color of a person is almost imaginable, and the operator is the person in the photograph image. Correct the skin color so that it looks natural.

What is more troublesome here is the element of human memory color. When the subject is a lemon, even if the actual color measured by the colorimeter and the color of the photograph match, the color of the photograph looks a little dull unless contrasted. This is because, as a human sense, the color of lemon is remembered to be vivid, whereas the real thing is not so vivid. Therefore, even if the original color tone can be corrected, that is not enough. Memories can be flesh tones, greens of trees, and blue sky.

On the other hand, in the case where human beings are involved in color correction, if the flesh color is matched with the memorized color, other colors will be displaced, so it is appropriate even if the flesh color does not match the memorized color. The degree of emphasis is determined so that it is within the range.

As described above, since the conventional color correction processing cannot compare with the original color, it cannot be automatically corrected, and even if it is corrected, it is difficult to satisfy the human color. In the end, there was the problem that humans had to be involved.

The present invention has been made in view of the above problems, and a color correction device, a color correction method, and a color correction control program capable of automatically executing optimum color correction processing in consideration of a memory color. The purpose is to provide a medium on which is recorded.

[0009]

In order to achieve the above object, the invention according to claim 1 separates a color image for each predetermined element color and at the same time outputs an image output device based on color image data representing strength and weakness. Is a color correction device that corrects the color image data so that the image output result becomes a desired color when a color image is output by performing image output for each element color, based on the color image data. Chromaticity determining means for obtaining the chromaticity of each pixel, target chromaticity pixel totalizing means for totalizing pixels whose chromaticity determined by the chromaticity determining means is within a predetermined range, and chromaticity within the predetermined range. A color correction amount judgment that corrects the same color correction amount according to the ratio of the totaled pixels to all pixels while obtaining the color correction amount that eliminates the difference between the predetermined optimum value for pixels and the above totalization result. And means, based on the color correction amount determined by correcting it is constituted comprising a color correction means for color correcting the image data.

In the invention according to claim 1 configured as described above, the chromaticity determining means determines the chromaticity of each pixel based on the color image data. Chromaticity represents the absolute ratio of color stimulus values and is independent of brightness. Therefore, an important part of the image (this is called an object) can be divided according to the range of chromaticity. For example, the range that can be taken by the skin color or the range that can be taken by the green color of the trees. Since this can be said about the chromaticity, the target chromaticity pixel totaling means totals the pixels when the chromaticity determined by the chromaticity determining means is within a predetermined range. In the above-mentioned example, if the obtained chromaticity is within the range of chromaticity that the skin color can take, the pixel is targeted for aggregation. The specific contents of the aggregation can be various values such as average value and median,
Summing up only the pixels whose chromaticity is within the predetermined range for all the pixels in the image corresponds to the fact that a person pays attention to a pixel that seems to be flesh color and judges its average color.

Therefore, what is next to be done is to judge whether or not it matches the stored color, and the color correction amount judging means determines the optimum value and the predetermined optimum value for the pixels having the chromaticity within the predetermined range. A color correction amount that eliminates the difference from the count result is calculated. However, if this color correction amount is applied as it is, only the flesh color will be the same as the memorized color, but the deviation in the other color portions will be unacceptable. Therefore, the color correction amount determination means corrects the same color correction amount according to the ratio of the totaled pixels to all pixels. As a result, adjustment is performed so that the color correction of the skin color portion does not excessively change the color of other portions. Then, the color correction means corrects the color of the image data based on the color correction amount obtained by the correction.

The chromaticity determining means determines the chromaticity from the color image data of each pixel, and may be converted into the chromaticity in consideration of the coordinate system of the color space adopted by the original color image data.
In this case, if the chromaticity itself is a direct element, it may be used, or if it is not a direct element, it is converted. The conversion may use a conversion table or may be calculated by a conversion formula. In this case, it does not necessarily have to be accurate, and may include an error with a small influence.

The target chromaticity pixel totaling means may determine whether the calculated chromaticity is within a predetermined range, and totalize the pixels within the predetermined range. In this case, it is not always necessary to make a binary decision as to whether or not it is within a certain range, and weighting may be changed and aggregation may be performed. Further, although the totaling method is extremely diverse, as an example in which the calculation amount is taken into consideration, the invention according to claim 2 is the color correction device according to claim 1, wherein the target chromaticity pixel totaling means sets the target pixel as a target pixel. For each determined pixel, the average value is summed up for each element color of the color image data, and the color correction amount determination means determines the optimum value for each element color for the color image data having the chromaticity in the predetermined range. It is provided as a configuration.

In the invention according to claim 2 configured as described above, the target chromaticity pixel totaling means totals an average value for each element color of the color image data for each pixel determined to be the target pixel. Although it may be calculated as chromaticity, it is calculated using the element colors of the color image data. On the other hand, the color correction amount determining means also has the optimum value for each element color with respect to the color image data having the chromaticity in the predetermined range correspondingly, so that the comparison for each element color can be performed as it is. The difference can be used as the correction amount of the element color.

Needless to say, although the amount of calculation increases as a totaling method, it is also possible to use median or standard deviation in addition to this.

With respect to the range of chromaticity to be aggregated by the target chromaticity pixel aggregating means, the invention according to claim 3 is directed to claim 1
Alternatively, in the color correction apparatus according to any one of claims 2 to 5, the target chromaticity pixel totaling unit is configured to total pixels for a range in which chromaticity of a memory color can be taken.

In the invention according to claim 3 configured as described above, pixels are aggregated in a range in which chromaticity that includes so-called human memory colors can be taken. In this case, it is not always necessary to obtain one totaling result in only one range, and a plurality of ranges may be designated and a plurality of totaling may be individually performed.

The color correction amount determination means obtains a color correction amount that eliminates a difference between a predetermined optimum value for pixels having a chromaticity within a predetermined range and the above-mentioned totaling result, and the totaled pixels are all pixels. The correction amount for the same color is corrected according to the proportion occupied. In this case, it is not always necessary to perform the two-step processing, and similar results may be obtained. For example, if you obtain something that reflects the difference between the optimum value and the aggregation result at the aggregation stage, use it, or use it if a result that includes the ratio to all pixels is obtained. I don't care. Further, the difference between the optimum value and the totalized result does not necessarily require a calculation of subtraction, and may be one that inherently includes such an intention.

Various modes are possible for the color correction amount. As an example, the invention according to claim 4 is the color correction device according to any one of claims 1 to 3,
The color correction amount determination means is configured to use a tone curve representing an input / output relationship when changing the intensity of each element color and to form a tone curve corresponding to the correction amount.

In the invention according to claim 4 configured as described above, the color correction amount determination means forms a tone curve according to the correction amount, and the color correction means inputs and outputs each element color according to the tone curve. The strength is changed so that the relationship is represented by the same tone curve.

The method of totalizing pixels having chromaticity within a predetermined range and reflecting the totalized result in the color correction amount does not necessarily have to be limited to an actual apparatus, and an example thereof is the invention according to claim 5. Is a color image is separated into each predetermined element color, and the image output device outputs an image for each element color based on the color image data indicating the strength and weakness. A color correction method for correcting the color image data so as to obtain a desired color, the step of obtaining the chromaticity of each pixel based on the color image data, and the obtained chromaticity is within a predetermined range. While the step of totalizing the pixels and obtaining the color correction amount that eliminates the difference between the predetermined optimum value for the pixels having the chromaticity within the predetermined range and the total result, A step of correcting the amount of the same color modified according to a percentage of pixels, based on the corrected color correction amount determined by some as structure and a step of color correcting the image data.

That is, there is no difference that the method is not limited to a substantial device and is effective as a method.

By the way, as described above, the color correction apparatus for judging the chromaticity and performing the color correction processing may exist alone or may be used in a state of being incorporated in a certain device. The idea includes various aspects. Further, it can be changed as appropriate, such as being realized by hardware or software.

When it comes to software for controlling a color correction device as an example of embodying the idea of the invention, it must be said that it naturally exists on a recording medium recording such software and is used.

As an example thereof, in the invention according to claim 6, the color image is color-separated for each predetermined element color, and the image output device outputs the image for each element color based on the color image data showing the strength. A medium for recording a color correction control program for correcting the above-mentioned color image data so that the image output result becomes a desired color when outputting a color image by performing the above-mentioned, based on the above-mentioned color image data. The chromaticity of the pixel is obtained, and the pixels having the obtained chromaticity within a predetermined range are totalized to eliminate the difference between the predetermined optimum value and the totalized result for the pixels having the chromaticity within the predetermined range. While correcting the color correction amount as described above, the same color correction amount is corrected according to the ratio of the total pixels to all pixels, and the image data is corrected based on the corrected color correction amount. There is a configuration that you want to modify.

Of course, the recording medium may be a magnetic recording medium or a magneto-optical recording medium, and any recording medium developed in the future can be considered in exactly the same manner. In addition, the duplication stage of the primary duplication product, the secondary duplication product, and the like is absolutely the same. In addition, the present invention is used even when a communication line is used as a supply method, and the same applies to a case where the present invention is written in a semiconductor chip.

Further, even when a part is software and a part is realized by hardware, there is no difference in the idea of the invention, and it is necessary to store a part on a recording medium. It may be in such a form that it is read as appropriate.

[0028]

As described above, the present invention can provide a color correction device which can approximate the judgment of a human and can automate the color correction processing by totaling using the chromaticity. it can.

Further, according to the second aspect of the present invention, whether or not the object to be totalized is judged by the chromaticity, but since it is the element colors of the color image data that are totaled, the calculation when using the totalized result And so on.

Further, according to the invention of claim 3,
By summing up the pixels of the memory color, the reflection degree of the correction is adjusted according to the number of pixels, and becomes closer to human judgment.

Further, according to the invention of claim 4,
Since the tone curve is used, it is easy to comprehensively add color corrections to other elements. In this case, not only the memory color portion is approximated to an ideal color, but also adjacent color areas are continuously changed, so that a pseudo contour due to a tone jump does not occur.

Further, according to the invention of claim 5,
A color correction method that exhibits the same effect can be provided, and
According to the present invention, it is possible to provide a medium in which the color correction control program is recorded.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a color correction system to which a color correction device according to an embodiment of the present invention is applied, and FIG. 2 is a schematic block diagram showing a concrete hardware configuration example.

In FIG. 1, an image input device 10 outputs color image data representing a photograph or the like as pixels in a dot matrix to a color correction device 20, and the same color correction device 20 performs optimum color correction according to the same color image data. Execute the process. The same-color correction device 20 outputs the color image data subjected to the color correction process to the image output device 30, and the image output device outputs the color-corrected image as pixels in a dot matrix. put it here,
The color image data output by the color correction device 20 determines the object and color of the image based on the chromaticity of each pixel, and determines the optimal color correction policy and degree in consideration of the overall color correction. It was done. Therefore, the color correction device 20
A chromaticity determination means, a target chromaticity pixel totalization means, a color correction amount determination means, and a color correction means are provided.

A specific example of the image input device 10 corresponds to the scanner 11, the digital still camera 12 or the video camera 14 in FIG. 2, and a specific example of the color correction device 20 is a computer 21, a hard disk 22 and a keyboard 2.
3 corresponds to a computer system including a CD-ROM drive 24, a flexible disk drive 25, a modem 26, and the like, and a specific example of the image output device 30 includes a printer 31, a display 32, and the like. In the case of the present embodiment, since the color of the pixel represented by the color image data is compared with the stored color to determine whether or not there is a deviation, the photographed data such as a photograph is suitable as the same color image data. It should be noted that the modem 26 is connected to a public communication line and can be connected to an external network via the same public communication line so that software and data can be downloaded and introduced.

In the present embodiment, the image input device 10
While the scanner 11 or the digital still camera 12 as an output outputs the gradation data of RGB (green, blue, red) as the color image data, the printer 31 as the image output device 30 outputs the CMY (cyan, magenta, (Yellow) or CMYK binary data in which black is added to this is required as an input, and the display 32 displays RG.
B gradation data is required as an input. On the other hand, the operating system 21a is operating in the computer 21, and the printer driver 21b and the display driver 21 corresponding to the printer 31 and the display 32 are provided.
c is incorporated. The color correction application 21d is controlled by the operating system 21a to execute processing, and executes printing and display processing in cooperation with the printer driver 21b and the display driver 21c as necessary. Therefore, the specific role of the computer 21 as the color correction device 20 is to input RGB gradation data to create RGB gradation data that has been subjected to optimum color correction, and to display it via the display driver 21c. The printer driver 21b.
Is converted into binary data of CMY (or CMYK) via the printer and printed by the printer 31.

As described above, in this embodiment, the computer system is incorporated between the image input / output devices to perform the color correction. However, such a computer system is not necessarily required, and the color image is not necessarily required. It can be applied to various systems that use data. For example, as shown in FIG. 3, a color correction device that corrects the color based on the chromaticity of each pixel is incorporated in the digital still camera 12a, and the converted color image data is used to display the display 32a.
The system may be such that it is displayed on the screen or printed on the printer 31a. Further, as shown in FIG. 4, in the printer 31b for inputting and printing the color image data without going through the computer system, the scanner 11b is used.
It is also possible to automatically determine the object and color of the image from the color image data input via the digital still camera 12b, the modem 26b, or the like, and correct the color.

The above-mentioned judgment of the object and the color correction accompanying it are concretely performed in the computer 21 as shown in FIG.
The color correction processing program corresponding to the flowchart shown in FIG. It should be noted that this flowchart corrects colors so that the so-called flesh color looks beautiful.

In this color correction processing, first, the skin-like pixels are totalized based on the chromaticity of each pixel. In addition, when performing the totaling, the totaling is performed for all the pixels while moving the target pixel as shown in FIG.

First, in step S110, the xy chromaticity of each pixel is calculated. Now, assuming that the RGB gradation data in the RGB color system of the target pixel is (R, G, B), r = R / (R + G + B) (1) g = G / (R + G + B) ... (2), chromaticity coordinates x, y in the XYZ color system
X = (1.1302 + 1.6387r + 0.6215g) / (6.7846-3.0157r-0.3857g)… (3) y = (0.0601 + 0.9399r + 4.5306g) / (6.7846-3.0157r-0.3857) g)… (4) The corresponding relationship is established. Here, since the chromaticity represents the absolute ratio of the color stimulus values without being influenced by the brightness, it can be said that it is possible to determine what kind of object the pixel is from the chromaticity. . For example, taking the skin color as an example, it is included in the range 0.35 <x <0.40… (5) 0.33 <y <0.36… (6), so this range is obtained when the chromaticity of each pixel is calculated. If it is inside, it can be said that the pixel is not mistaken even if it is considered as a pixel showing human skin.

Therefore, in step S120, it is determined whether the converted xy chromaticity based on the RGB gradation data of each pixel is within the skin color range, and if it is the skin color, the same is performed in step S130. The color image data of the pixels is totaled. This aggregation means simple addition of RGB gradation data. In addition, as will be described later, the number of pixels is also counted in order to obtain an average value for pixels determined to be flesh color.

After that, irrespective of whether the skin color is determined or not, the target pixel is moved in step S140, and the process is repeated until it is determined in step S150 that all the pixels are finished. Then, when the processing is completed for all the pixels, the total result is divided by the number of pixels in step S160 to obtain an average value (Rs.ave, Gs.ave, Bs.ave).

As is clear from the above, step S11
The chromaticity determination means is composed of software processing for calculating xy chromaticity at 0 and hardware for executing the software processing. Further, in step S120, it is determined whether or not the same chromaticity is within a predetermined target range, and if the same chromaticity is within the predetermined target range, the process of totalizing the color image data in step S130 is performed in steps S140 and S150. Is performed for all pixels while moving the target pixel, and the total result is divided by the number of pixels to obtain an average value in step S160. Therefore, the software processing and the hardware configuration for executing the software processing are the target chromaticity pixel totaling means. Make up.

On the other hand, ideal values (Rs.ideal, Gs.ideal, Bs.ideal) are obtained in advance for skin-colored pixels which are considered to be preferable. This ideal value is different from the colorimetric result when it comes to memory colors. In the case of flesh color, the illusion that the flesh color that is intentionally shifted is more correct than the flesh color that the colorimetric results match. This is based on a fixed perception of the skin color that appears in photographs as a human sense,
It is called memory color. In the present invention, the ideal value including such a memory color is set, and the color is corrected so as to eliminate the difference from the ideal value. Therefore, the ideal value is not limited to the actual color. Any color that is widely expected as a target may be used.

The average value (Rs.ave, Gs.ave, Bs.ave) of the RGB gradation data for the skin tone pixel and the ideal value (Rs.ideal, Gs.ideal, Bs.ave) obtained in the case of a desirable skin tone. The difference from ideal) essentially means the deviation in the color image data.

However, it is not preferable to directly apply this difference as the correction amount. For example, if the same correction amount is applied to all pixels, the flesh-colored portion may be a preferable color, but the color of the pixels other than the flesh-colored portion may be greatly affected.

Therefore, in this embodiment, the ratio of the number of pixels of skin color to the total number of pixels (skin color ratio) is calculated and the correction amount is adjusted. That is, the correction amounts ΔR, ΔG, ΔB
ΔR = ks (Rs.ideal-Rs.ave) (7) ΔG = ks (Gs.ideal-Gs.ave) (8) ΔB = ks (Bs.ideal-Bs.ave) (9) Here, the skin color ratio ks is calculated by ks = (skin color pixel number / total pixel number).

The color correction amount thus obtained cannot be used as it is for the correction of the color image data. In this embodiment, the tone curve is formed by using the correction amount in step S180. FIG. 7 is an explanatory diagram showing a tone curve formation state.

The tone curve means the input-output relationship when converting the RGB gradation data by changing the emphasizing degree, and taking 256 gradations of "0" to "255" as an example, the gradation " A spline curve that passes through the output values specified for three predetermined points of "0", gradation "255", and a gradation between them is used. As an example, assuming that the intermediate gradation is “64”, the input values are “0”,
"64" and "255", and output values are "0" and "6"
When it is "4" or "255", the input / output relationship is matched and the tone curve becomes a straight line. However, when the output value with respect to the input value “64” is not “64”, a gentle curve is drawn as shown in FIG. 7 to form the input / output correspondence.
In the present embodiment, the RG described above as the intermediate gradation is used.
The average values (Rs.ave, Gs.ave, Bs.ave) of the B gradation data are used as control points, and the above-mentioned correction amounts ΔR, ΔG, ΔB are reflected in the tone curve at each point. By changing the control point in this way, the ideal value (Rs.ideal, Gs.ideal, Bs.i
deal).

In step S190, the color correction is executed on the color image data by converting the element colors of the color image data for all pixels again using the tone curve thus obtained. .

Of course, in this way, the difference between the totalization result and the ideal value is calculated, and the correction is performed according to the ratio of the target pixel to all the pixels, and the tone curve is calculated based on the calculated color correction amount. Forming step S180
It can be said that the processing of step S21 and the hardware configuration for executing these steps constitute the color correction amount determination means, and step S19
It can be said that the process of converting the color image data with 0 and the hardware configuration for executing the process configure the color correcting unit.

Up to now, an embodiment has been described in which the object to be modified is the skin color as an example for ease of understanding, but the object to be color-corrected is not limited to the skin color. Taking memory colors as an example, in addition to skin tones, there are many desires to make the green of trees vivid and to make the blue sky clear blue. FIG. 8 shows a modification in which the target of color correction can be selected.

In this example, the target of color correction is selected in the first step S205. The computer 21 displays the screen shown in FIG. 9 on the screen of the display 32, and prompts the operator to select a color correction target. In this example, the flesh color correction that cleans the flesh tones, the green correction that refreshes the green of the trees, and the blue sky color correction that makes the clear sky color are displayed side by side, and a check box is provided for each You can choose to. In this case, they can be selected redundantly. And
If you click the "OK" button after checking the desired check boxes, the checked ones will be flagged as prepared for each target, and steps S210 to S2 will be performed.
The loop process of 50 is started.

This loop processing is to calculate the chromaticity of all the pixels while moving the target pixel in the same manner as in the previous example, and in step S210, (1) to (4) for the target pixel. ) Xy chromaticity is calculated based on the equation. In the next step S215, step S20
With reference to the flag set in step 5, it is determined whether the operator has selected the flesh color correction. Then, if it is selected, in step S220, the aggregation processing is performed on the skin color pixels. This counting process is performed in step S in the previous example.
Similar to steps 120 and S130, if the xy chromaticity obtained in step S210 is within the range of chromaticity that the skin color can take, RGB gradation data is totaled for each element color.

In the next step S225, it is determined whether or not the operator has selected the green correction by referring to the flag as in the case of the skin color correction. And if you have selected,
It is determined whether or not the xy chromaticity of this pixel is within the range of chromaticity corresponding to the green color of the trees, and if it is within the range, step S230.
Total at. This total is calculated in an area different from the area used for skin color total.

Thereafter, in step S235, the same judgment is performed for blue-sky color correction, and in step S240, another area is totaled.

Then, in step S245, the target pixel is moved, and the process is repeated until it is determined in step S250 that all pixels have been moved. In this example, there may be a plurality of objects to be color-corrected, but even in that case, if the chromaticity of the target pixel is within the predetermined range in step S215 to S240, the target color is calculated in the sense that the totaling is performed. It can be said that this constitutes a degree pixel aggregation means.

When the chromaticities of all the pixels are totaled, in steps S255 to S265, the correction amount is calculated for each color based on the totalized result. Note that in this example, unlike the previous example, the process of obtaining the average value from the totalization result is simultaneously performed in this correction amount end processing, and the calculation procedure and the like can be changed as appropriate. Although the flesh color correction has been described in the above example, the processing is exactly the same for the green color correction and the blue sky color correction. That is, the average value is calculated based on the totalized result, the difference from the ideal value obtained for the preferable image is obtained, and the correction amount is corrected by multiplying the green color ratio and the blue sky color ratio like the skin color ratio. .

When step S265 is completed, there are three correction amounts. This is because the flesh color correction, the green color correction, and the blue sky color correction are individually added up to obtain the correction amount. Therefore, in the present embodiment, these totalization results are added so as to be superposed. That is, assuming that the processing target is further expanded, the color correction amounts ΔR, ΔG, and ΔB for the respective processing targets are

[0061]

[Equation 1]

[0062]

[Equation 2]

[0063]

[Equation 3]

Is calculated as put it here,

[0065]

[Equation 4]

It is assumed that there is no duplicate count.

The color correction amount ΔR obtained in this way,
The process of step S270 is to form a tone curve as shown in FIG. 7 based on ΔG and ΔB. In this case, the control points are Σki ・ Ri.ave, Σki ・ G
i.ave, Σki · Bi.ave. Of course, step S255
The processing from S270 to S270 constitutes a color correction amount determination means. When the tone curve is formed, the color image data is modified in step S275.

The color correction device described above can also be applied as a printer driver. Normally, the printer driver cannot temporarily store the input data in the process of processing and outputting the data. Therefore, there is a limitation in dividing the area by a desired amount and changing the processing. However, (11)
By setting the color correction amounts for a plurality of elements as shown in Expressions (12), effective correction can be performed even in such a printer driver having many restrictions.

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

First, a description will be given according to the above embodiment.
It is assumed that a photographic image as shown in FIG. 10 is read by the scanner 11 and printed by the printer 31. Then, first, while the operating system 21a is running on the computer 21, the color correction application 21d is activated to cause the scanner 11 to start reading a photo. When the read color image data is captured by the color correction application 21d via the operating system 21a, the pixel to be processed is set to the initial position. Then, in step S110 (1)
The xy chromaticity of the pixel is calculated based on Expressions (4), and in step S120, it is determined whether the x value and the y value are within the chromaticity range of the skin color. And
If it is within the chromaticity range of the skin color, the color image data of the pixel is totaled for each element color in step S130. As shown in FIG. 10, at least the limbs and the face should be determined to be flesh-colored pixels regardless of the brightness, and in this example, several percent of all pixels are tabulated as flesh-colored pixels. The above process is repeated while moving the target pixel in step S140 until it is determined in step S150 that all pixels have been executed.

When the execution is completed for all pixels, the total result is divided by the number of skin color pixels to calculate an average value in step S160, and the difference between the ideal value and the average value of the skin color pixels is calculated in step S170. Meanwhile, the flesh color ratio corresponding to the ratio between the flesh color pixel number and the total pixel number is multiplied, and step S180
To form a tone curve. Then, step S19
At 0, the data is converted for each element color of the color image data based on this tone curve to correct the color. Then, while trying to bring the flesh color closer to the ideal value, the correction amount is set conservatively in consideration of the ratio between the number of flesh color pixels and the total number of pixels. .

In other words, in the example shown in FIG. 10, the correction amount is corrected by multiplying the difference between the average value of the totaled skin color pixels and the ideal value by a skin color ratio of several%, and the corrected correction amount is corrected. It will be necessary to correct the color by forming a tone curve suitable for.

Further, in the case where the correction target can be selected as in the later example, if flesh color correction, green correction and blue sky color correction are selected, step S2 is performed for all pixels.
In step 10, xy chromaticity is calculated, and steps S215 to S2 are performed.
At 40, the total is individually calculated for each correction target. In the example shown in FIG. 10, the xy chromaticity falls within the respective target ranges in the flesh-colored portion of the person image, the leaves of the tree, and the blue sky portion of the back, and is aggregated.

When all the pixels are finished, the color correction amount for each target process is calculated in consideration of the occupation ratio of each target pixel in steps S255 to S265, and the tone curve in which the correction amounts are superposed is calculated in step S270. To form. Finally, in step S275, color correction is executed on the color image data of all pixels. Then, the correction to make the skin color closer to the ideal value, the correction to make the green of the leaves look refreshing, and the correction to make the blue sky a clear color are adjusted and executed according to the occupancy of each pixel. .

Of course, each color-corrected color image data is displayed on the display 32 via the display driver 21c, and if good, the printer driver 2
It is printed by the printer 31 via 1b. That is,
The printer driver 21b inputs the color-corrected RGB gradation data, and after a predetermined resolution conversion, the printer 31
The rasterization corresponding to the print head area is performed, the rasterized data is color-converted from RGB to CMYK, and then the CMYK gradation data is converted to binary data and output to the printer 31.

With the above processing, the color image data of the photograph read by the scanner 11 is automatically subjected to the optimum color correction, displayed on the display 32, and then printed by the printer 31.

As described above, the computer 21, which is the center of the color correction, calculates the xy chromaticity of each pixel in step S110, and in steps S120 and S130, the same chromaticity is within the range in which the chromaticity of the skin color can be obtained. If it is within the range, the total is calculated, and when the total is calculated for all the pixels, the average value is obtained in step S160 and the color correction amount considering the number of pixels is calculated in step S170. Color pixels can be accurately aggregated, and the correction amount is adjusted in consideration of the number of pixels.
It is possible to execute optimum color correction without significantly affecting the colors of surrounding pixels.

[Brief description of drawings]

FIG. 1 is a block diagram of a color correction system to which a color correction device according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram of specific hardware of the same color correction apparatus.

FIG. 3 is a schematic block diagram showing another application example of the color correction apparatus of the present invention.

FIG. 4 is a schematic block diagram showing another application example of the color correction apparatus of the present invention.

FIG. 5 is a flowchart showing a color correction process in the color correction device of the present invention.

FIG. 6 is a diagram showing a state in which processing target pixels are moved.

FIG. 7 is an explanatory diagram showing a tone curve for converting gradation data with a predetermined intensity.

FIG. 8 is a flowchart showing a color correction process according to a modified example.

FIG. 9 is a diagram showing a target of color correction that can be selected in the same color correction processing.

FIG. 10 is a diagram showing an original photographic image for color correction.

[Explanation of symbols]

10 ... Image input device 20 ... Color correction device 21 ... Computer 21a ... Operating system 21b ... printer driver 21c ... Display driver 21d ... Color correction application 22 ... Hard disk 23 ... Keyboard 24 ... CD-ROM drive 25 ... Flexible disk drive 26 ... Modem 30 ... Image output device

Continued front page    F term (reference) 5B057 CA01 CA08 CA16 CB01 CB08                       CB16 CE17 CE18 CH01 CH11                 5C055 AA14 BA05 BA06 BA07 BA08                       EA05 FA21 HA37                 5C066 AA11 BA17 CA17 EB02 GA01                       GB03 HA03                 5C077 MP08 PP32 PP33 PP37 PP39                       PP46 PQ12 PQ22                 5C079 HB01 HB03 HB05 HB12 LA24                       LB01 MA01 MA11 NA03 NA18

Claims (6)

[Claims] 1. An image for outputting a color image by color-separating a color image for each predetermined element color and outputting an image for each element color by an image output device based on color image data representing strength and weakness. A color correction device that corrects the color image data so that the output result becomes a desired color, and a chromaticity determination means for determining the chromaticity of each pixel based on the color image data, and the chromaticity determination means. Target chromaticity pixel totalizing means for totaling pixels for which the obtained chromaticity is within a predetermined range, and eliminating the difference between the above-mentioned totaling result and a predetermined optimum value for pixels with chromaticity within the predetermined range. Color correction amount determining means for correcting the same color correction amount according to the ratio of the totalized pixels to all pixels while obtaining such color correction amount, and the image data based on the corrected color correction amount. Color correction apparatus characterized by comprising a color correction means for correcting color. 2. The color correction device according to claim 1, wherein the target chromaticity pixel totaling unit totalizes an average value for each element color of the color image data for each pixel determined to be a target pixel. The color correction device is characterized in that the color correction amount determination means has an optimum value for each element color with respect to the color image data having the chromaticity within the predetermined range. 3. The color correction device according to claim 1 or 2, wherein the target chromaticity pixel totaling means totals pixels for a range of chromaticity of a memory color. A color correction device characterized by performing. 4. The color correction apparatus according to any one of claims 1 to 3, wherein the color correction amount determination means displays a tone curve representing an input / output relationship when changing the intensity of each element color. A color correction device which is utilized and forms a tone curve corresponding to the correction amount. 5. An image for outputting a color image by color-separating a color image for each predetermined element color and outputting an image for each element color by an image output device based on the color image data showing the intensity. A color correction method for correcting the above-mentioned color image data so that an output result becomes a desired color, the step of obtaining the chromaticity of each pixel based on the above-mentioned color image data, and the obtained chromaticity is within a predetermined range. The step of totalizing the pixels within the range, and the totaling pixels while obtaining the color correction amount that eliminates the difference between the total value and the predetermined optimum value for the pixels having the chromaticity in the predetermined range. A color correction method comprising: a step of correcting the same color correction amount according to a ratio of all pixels; and a step of correcting the color of the image data based on the color correction amount obtained by the correction. 6. A computer for outputting a color image by color-separating a color image for each predetermined element color and outputting an image for each element color by an image output device based on the color image data showing the intensity. Is a medium in which a color correction control program for correcting the color image data is recorded so that the image output result becomes a desired color, and the chromaticity of each pixel is obtained based on the color image data. The chromaticity is aggregated for pixels that are within a predetermined range, while obtaining a color correction amount that eliminates the difference between the predetermined optimum value and the aggregated result for pixels with chromaticity within the predetermined range, A color correction control program characterized by correcting the same color correction amount according to the ratio of the totaled pixels to all pixels and performing color correction on the image data based on the corrected color correction amount. A medium that records grams.