JP2002027266A - Image processing system and image processing method and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control color tone correction by making a decision whether an image requires color tone correction or not when writing data is received and an image is displayed or printed. SOLUTION: The image processing system has a function for receiving writing data containing RGB image data, for correcting the color tone of the RGB image data contained in the writing data, and for delivering corrected data to an image output unit. The system comprises a writing data analyzing means 202 for extracting the color space characteristics information of the RGB image data from the writing data, a section 303 for determining the correcting content of the RGB image data using a specified feature quantity calculated from he RGB image data, and color converting means (304, 305) wherein the color converting means (304, 305) performs color tone correction of the RGB image data according to a correcting content determined at the correction content determining section 303 only when the color space characteristics information of the RGB image data can not be extracted by the writing data analyzing means 202.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image processing system, an image processing method, and a recording medium.

[0002]

2. Description of the Related Art In a multimedia system centered on a host computer, a color matching system (CMS) for performing color matching processing of image data between an input device and an output device has been developed.

[0003] A color sync (TM) of Apple Inc., which is a typical CMS framework, converts an image signal of a color space (Device Dependent Color Space) dependent on an input device into a device independent color space (Device Independent Col- umn).
or Space), and further converts an image signal in a device-independent color space into a color space that depends on an output device, thereby realizing a common CMS on the system.

[0004] Data representing conversion characteristics for this conversion process is called a profile, which is prepared in a host computer for each device, and an image signal is automatically or manually selected at the time of conversion according to the conversion characteristics of the profile. Is converted.

In the above-described color matching system, since the input signal is color-converted into the output signal via a device-independent color space, colorimetrically consistent color reproduction can be performed.

[0006] On the other hand, with the spread of the Internet and intranets, documents are being shared, and there is an increasing demand to be able to accurately grasp colors even on a remote computer. Therefore, photographic image data, etc.
When the image is corrected beforehand and attached to the document, saved and stored with the color management information of the photographic image added, and viewed remotely, the CMS architecture described above is used to match the monitor characteristics of the remote computer. Functions such as displaying are beginning to be provided in some applications.

As described above, while a platform for accurate color reproduction is prepared, digital photographic image data is rapidly spreading with the spread of scanners and digital cameras. When printing out such photographic image data, he would like to make use of the characteristics of digital images to make color corrections according to his liking for images that are underexposed or backlit rather than accurately reproducing colors. The demand is increasing.

Therefore, Japanese Patent Application Laid-Open No. Hei 10-208034 analyzes RGB image data to perform color tone correction, and outputs the image data to a printer through a printer driver or displays the image on a display screen through a display driver. . Here, as the color tone correction, R
The luminance distribution of the GB image data is obtained, and the contrast between the luminance of the conversion source and the luminance of the conversion destination is changed from a direct proportional state to a state in which the luminance is appropriately distorted into an S-shape based on the standard deviation, thereby to improve the contrast. A process for automatic correction has been proposed. In addition, a device such as a binary image determination or a business graph is determined based on the state of the luminance distribution so that the contrast correction process is not performed. ing.

In such conventional automatic image correction processing,
An effect of automatically adjusting the color tone and outputting an image of a digital camera or a scanner image with underexposure / overexposure / color balance being lost is exhibited.

[0010]

However, according to the technique disclosed in Japanese Patent Application Laid-Open No. Hei 10-208034, the printer automatically determines whether or not color tone correction is necessary based on only RGB image data. Since the correction content is determined, there is a problem that even if the data has been corrected, the correction process is performed again at the time of output to the printer.

As described above, when an attempt is made to determine what color correction should be performed only from the RGB image data,
Judgment becomes difficult, and R which does not need to be corrected originally
The risk of correcting the GB image data increases.

For example, in the case of an Internet novice who is not so conscious of color management, an image captured by an image input device is often disclosed as it is, but a company in which the appearance of colors on a web browser is regarded as important. Advertisements and product images are often published after they have been modified for better appearance.

However, since the monitor characteristics used by the remote user who browses the image information are various, in such a case where the color appearance is important, the RGB for the drawing object in the document is used.
It is common to specify properties. By doing so, when browsing a document to which color management information has been added, accurate display is possible by displaying the document using a color management mechanism.

The present invention relates to an image processing system and an image processing system capable of determining whether or not an image requires color tone correction and controlling color tone correction processing when displaying and printing an image upon receiving drawing data. It is an object to provide a processing method and a recording medium.

[0015]

According to a first aspect of the present invention, there is provided a method for receiving drawing data including RGB image data and receiving RGB data included in the drawing data.
In an image processing system having a function of correcting a color tone of image data and outputting the corrected image data to an image output device, a drawing data analysis unit for extracting color space characteristic information of RGB image data from the drawing data, A correction amount determining unit that determines the correction content of the RGB image data using the characteristic amount calculated by the characteristic amount calculation unit; and a color conversion processing unit. The color conversion processing means performs the color tone correction processing of the RGB image data with the correction content determined by the correction content determination means only when the drawing data analysis means cannot extract the color space characteristic information of the RGB image data. Features.

According to a second aspect of the present invention, in the image processing system according to the first aspect, the color conversion processing means includes a step of extracting the color space characteristics of the RGB image data by the drawing data analysis means. The color conversion processing is performed using the color space characteristics of the RGB image data and the color space characteristics of the image output device so that the colorimetric values match.

According to a third aspect of the present invention, there is provided an image having a function of receiving drawing data including RGB image data, correcting the color tone of the RGB image data included in the drawing data, and outputting the corrected tone to an image output device. In the processing system,
A drawing data analysis unit that extracts color space characteristic information of RGB image data from the drawing data; a feature calculation unit that obtains a predetermined feature from the RGB image data; and a feature calculated by the feature calculation unit. And a color conversion processing means for determining a plurality of types of correction contents for the RGB image data, and the color conversion processing means uses a drawing data analysis means to convert color space characteristic information of the RGB image data. When the color space characteristic information of the RGB image data cannot be extracted and when the color space characteristic information of the RGB image data cannot be extracted, different correction contents are selected from among a plurality of types of correction contents, and different color tone correction processes are performed on the RGB image data. And

According to a fourth aspect of the present invention, in the image processing system of the first or third aspect, the color conversion processing means determines at least one of a dynamic range, a tone curve, and a color balance of the image data. It is characterized in that color tone correction processing for correction is performed.

According to a fifth aspect of the present invention, in the image processing system of the third aspect, if the color space characteristics of the RGB image data can be extracted by the drawing data analyzing means, the color space characteristics of the RGB image data can be extracted. Is characterized in that the type of image to be corrected is limited as the content of the correction as compared with the case where the image cannot be extracted.

According to a sixth aspect of the present invention, in the image processing system according to the third aspect, when the color space characteristics of the RGB image data can be extracted by the drawing data analysis means, the color space characteristics of the RGB image data can be extracted. Is characterized in that the criterion for determining the feature amount to be corrected is limited as the content of correction, as compared with the case where it cannot be extracted.

According to a seventh aspect of the present invention, in the image processing system according to the third aspect, when the color space characteristics of the RGB image data cannot be extracted by the drawing data analysis means, the image data is used to detect the subject. The brightness is determined to determine the content of the correction, and the color content of the RGB image data can be extracted by performing the color tone correction process on the RGB image data with the content of the correction. It is characterized in that the content is determined, and the color tone correction processing of the RGB image data is performed with the correction content.

According to an eighth aspect of the present invention, there is provided an image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected data to an image output device. It is determined whether or not the color space characteristic information is included. If the color space characteristic information is not included, a predetermined characteristic amount is obtained from the RGB image data, and RGB is determined using the predetermined characteristic amount.
It is characterized in that color tone correction of image data is performed.

According to a ninth aspect of the present invention, there is provided an image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected image data to an image output device. It is determined whether or not the color space characteristic information is included. If the color space characteristic information is included, the color tone having a limited correction range is compared with the case where the color space characteristic information is not included. The correction is performed.

According to a tenth aspect of the present invention, when drawing data including RGB image data is received, the color tone of the RGB image data is corrected and output to an image output device, the color of the RGB image data is added to the drawing data. It is determined whether or not the space characteristic information is included. If the color space characteristic information is not included, a predetermined characteristic amount is obtained from the RGB image data, and the RGB image data is obtained using the predetermined characteristic amount. Is a computer-readable recording medium on which a program for causing a computer to execute the color tone correction processing is recorded.

According to the eleventh aspect of the present invention, when drawing data including RGB image data is received, the color tone of the RGB image data is corrected and output to an image output device, the drawing data includes the color of the RGB image data. It is determined whether or not the space characteristic information is included, and when the color space characteristic information is included, the color tone correction with a limited correction range is performed as compared with the case where the color space characteristic information is not included. This is a computer-readable recording medium on which a program for causing a computer to execute a process to be performed is recorded.

According to a twelfth aspect of the present invention, an image having a function of receiving drawing data including RGB image data, correcting the color tone of the RGB image data included in the drawing data, and outputting the corrected tone to an image output device. A drawing data analysis unit for detecting, from the drawing data, a type of the image generating apparatus that has generated the RGB image data;
A feature amount calculating unit for obtaining a predetermined feature amount from the GB image data, a correction content determining unit for determining the correction content of the RGB image data using the feature amount calculated by the feature amount calculating unit, a color conversion processing unit, Wherein the color conversion processing means performs color tone correction processing of the RGB image data with the correction content determined by the correction content determination means in accordance with the type of the image generation device detected by the drawing data analysis means. It is characterized by the fact that it is designed to be switched.

The invention according to claim 13 is the first invention.
3. In the image processing system according to item 2, when the image generation device is an image display device, the color conversion processing unit does not perform color tone correction processing, and performs color space characteristics of the image display device and color space of the image output device. The color conversion processing is performed so that the colorimetric values match using the characteristic.

The invention according to claim 14 is the first invention.
3. In the image processing system according to item 2, when the image generation device is an image input device, the color conversion processing unit determines at least a dynamic range and a tone curve of the image data according to the correction content determined by the correction content determination unit. , Color tone correction processing for correcting any of the color balance.

[0029] The invention according to claim 15 provides the invention according to claim 1.
3. In the image processing system according to item 2, when the image generation device cannot be determined, the color conversion processing unit determines at least a dynamic range, a tone curve, and a color balance of image data according to the correction content determined by the correction content determination unit. Is characterized in that color tone correction processing for correcting any of the above is performed.

[0030] Further, the invention according to claim 16 is based on claim 1.
3. In the image processing system according to item 2, when the image generation device is not defined, the type of image to be corrected is limited and color tone correction processing is performed as compared with the case where the image generation device is an image input device. It is characterized by performing.

Further, the invention according to claim 17 is based on claim 1
3. In the image processing system according to item 2, when the image generation device is not defined, color tone correction is performed by limiting a reference of a feature amount to be corrected, as compared with a case where the image generation device is an image input device. Processing is performed.

In the image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected RGB image data to an image output device, the image processing apparatus according to the present invention preferably generates an image in which RGB image data is generated. It is characterized in that the type of the generating device is read from the drawing data, and whether to correct the color tone of the RGB image data is switched according to the type of the read image generating device.

Further, the invention according to claim 19 is based on claim 1
8. In the image processing method according to 8, the color tone correction process of the RGB image data is not performed when the type of the image generating device is the image display device, and the RGB image data is not processed when the type of the image generating device is the image input device or unknown. It is characterized in that color tone correction processing is performed.

The invention according to claim 20 is the first invention.
9. The image processing method according to item 9, wherein different color tone correction processes are performed depending on whether the type of the image generating device is an image input device or unknown.

According to a twenty-first aspect of the present invention, the type of the image generating device that has generated the RGB image data is read from the drawing data, and the color tone of the RGB image data is corrected according to the type of the read image generating device. It is a computer-readable recording medium on which a program for causing a computer to execute a process of switching whether or not to execute is recorded.

[0036]

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

FIG. 1 is a diagram showing an example of an image processing system according to the present invention. In the example of FIG. 1, the image processing system includes a display 100, a digital camera 101,
It has a scanner 102, a computer 103, an image output device 104, and an image processing device 200.

Here, software such as various color correction applications and printer drivers can be mounted on the computer 103. The digital camera 101 and the scanner 102 are input devices for capturing image data to be processed. The display 10
Reference numeral 0 denotes an output device for displaying image data, and the image output device 104 is an output device for printing out image data. The image output device 10
As 4, a color printer, a color copier or a color facsimile machine can be used.

FIG. 2 is a diagram for explaining the processing functions of the computer 103 and the image processing device 200 in the image processing system of FIG. Referring to FIG. 2, the computer 103 has a function of controlling the image processing apparatus 200. When the computer 103 receives an output command from an operator, the computer 103 captures image data or image data. Is converted into a series of drawing data and transmitted to the image processing apparatus 200.

The image processing apparatus 200 also stores a drawing data sent from the computer 103 in a buffer memory 201, reads out the drawing data from the buffer memory 201, and stores the drawing data attributes (graphics drawing data, image drawing data). Drawing data analysis means 202 for interpreting data and text drawing data); graphics image processing means 203 for performing graphics image processing when the drawing data is graphics; and graphics data processing means 203 for performing graphics image processing. Image processing means 204 for performing image processing for images, text image processing means 205 for performing image processing for text when the drawing data is text, image processing means for graphics 203, image processing for image Means 204, text image processing means 20 From data subjected to image processing and raster image generating means 206 for generating a raster image (raster data) by any of the image processing means,
A transmission data generation unit 207 that converts the raster data into data (transmission data (for example, print data)) that can be interpreted by the image output device 104.

In the configuration example shown in FIG.
After the drawing data transmitted from the computer 103 is temporarily stored in the buffer memory 201, the image output device 1
04 is converted to interpretable data.

As an example of the conversion process to data that can be interpreted by the image output device 104, first, the drawing data analysis unit 2
02 reads out the drawing data from the buffer memory 201 and transmits the data to various image processing means while interpreting the attributes of the drawing data. For example, in the case of drawing graphics, a drawing command is sent to the graphics image processing means 203, and in the case of drawing an image, a drawing command is sent to the image processing means 204. The data subjected to appropriate image processing by the various image processing means in this way is output to the raster image generation means 206 by the raster image generation means 206.
After being aggregated into one plane of raster data, the transmission data generation unit 207 adds information necessary for communication with the image output device 104 to generate final data for the image output device 104.

First Embodiment FIG. 3 is a diagram showing a configuration example of a drawing data analyzing means 202 and an image image processing means 204 according to a first embodiment of the present invention. Referring to FIG. 3, the image processing unit for image 204 includes a feature amount calculation unit 302 that analyzes image data included in the drawing data and calculates a predetermined feature amount.
A correction content determination unit 303 that determines what kind of color correction is to be performed based on the feature value calculated by the feature value calculation unit 302 (determines the content of the color correction), and a correction content determination unit 3
A color conversion parameter setting unit 304 for setting a color conversion parameter for realizing the color correction content determined in step 03
And a color conversion processing unit 305 that performs a color conversion process on image data based on the color conversion parameters set by the color conversion parameter setting unit 304.

That is, image processing means for image 204
Has a function of analyzing at least the characteristics of image data and generating a color conversion parameter for performing appropriate color tone correction.

Incidentally, the image processing means for image 204
The image data input to the
(Green, blue, red) gradation data, and the image format is a bitmap format. Although the number of gradations of each color component is generally 8 bits = 256 gradations, another gradation number such as 64 or 512 may be used.

The image processing means for image 204 may be provided with a halftone conversion means for converting the data into data that can be output by the image output device 104, a resolution conversion means for converting the resolution, and the like.

By the way, in the first embodiment of the present invention,
The drawing data analysis unit 202 also functions as a color space characteristic extraction unit that extracts color space characteristic information of RGB image data from the drawing data, and the color conversion parameter setting unit 304
A color conversion parameter used for color conversion processing is controlled based on a detection result of RGB color space characteristic information (header information (for example, profile information) of image data) obtained by the drawing data analysis unit 202.

In other words, in the first embodiment of the present invention, the color conversion parameter setting unit 304 and the color conversion processing unit 30
Reference numeral 5 denotes the RGB content of the correction determined by the correction content determining unit 303 only when the drawing data analysis unit 202 cannot extract the color space characteristic information of the RGB image data.
The color tone correction processing of the image data is performed.

In the present invention, any color space characteristic information can be used.
or Consortium) profile is particularly famous as color space characteristic information.

Next, the overall operation of the image processing means 204 according to the first embodiment of the present invention will be described.

First, the drawing data analysis means 202 performs detection processing of RGB color space characteristic information from the image drawing data. For example, in a bitmap format, which is an image data format of the Windows (registered trademark) system, the color space characteristics of the RGB image data can be defined in the header information portion of the image data in the drawing data. Therefore, as a result of searching for the header information portion in the drawing data, the RGB
If the color space characteristics are described, the color conversion parameters used for the color conversion processing can be controlled based on the description.

When detecting the RGB color space characteristics from the drawing data, the drawing data analysis means 202 gives the color space characteristic information to the color conversion parameter setting section 304. on the other hand,
When the RGB color space information is not described in the drawing data, a code meaning undefined is given to the color conversion parameter setting unit 304. The drawing data analysis unit 202 separates the image data portion in the image drawing data from the header information portion, and
And a color conversion processing unit 305.

The color conversion processing unit 305 is a color conversion device compatible with color management.
In step 5, color conversion processing is performed using the color space characteristic information of the input device and the color space characteristic information of the output device.

Now, when the drawing data analysis unit 202 detects the RGB color space characteristic information from the drawing data, the color conversion parameter setting unit 304 inputs the detected color space characteristic information to the color conversion processing unit 305. The color space characteristic is given as it is, whereby the color conversion processing unit 305 uses the detected color space characteristic information as the input color space characteristic,
When the image output device 104 is a printer, color conversion of image data is executed using the color space characteristic information of the printer as an output color space characteristic.

As described above, when the drawing data includes the color space characteristic information, the color tone correction processing is not performed, and the color conversion based on the colorimetric matching based on the color space characteristic information is performed.

On the other hand, when the RBG color space characteristic information is not detected from the drawing data by the drawing data analysis means 202, the color conversion parameters for performing the color tone correction by operating the feature amount calculation unit 302 and the correction content determination unit 303. Generate That is, first, the feature amount calculation unit 302 receives the image data from the drawing data analysis unit 202, calculates the feature amount for performing the color tone correction, and sets the correction content determination unit 30
Send to 3. The correction content determination unit 303 determines how to correct the image data based on the feature amount calculated by the feature amount calculation unit 302. Here, examples of correction content candidates include dynamic range correction, tone curve correction, and color balance correction, but other methods may be used. When the correction content is determined by the correction content determination unit 303, the color conversion parameter setting unit 304 generates a correction parameter that realizes the correction content. Further, the color conversion parameter setting unit 304 combines the generated correction parameters with predefined default color conversion parameters (for example, set in a parameter storage memory (not shown)) to convert the RGB image data into colors. A new color conversion parameter for conversion is generated, and the generated color conversion parameter is provided to the color conversion processing unit 305 as an input color space characteristic. As a result, the color conversion processing unit 305 can perform color tone correction and output an appropriate color-corrected image.

The above color conversion parameters include:
A gamma table for tone conversion may be used, or a matrix conversion parameter (for example, an ICC color profile) for converting an input RGB signal into an XYZ signal or the like.
And so on.

Next, a method of correcting a color tone will be described.
When automatic exposure and automatic white balance do not operate properly when shooting with a digital camera, etc., when image data is transmitted from a digital camera or the like and output to an image display device or image output device, the gradation balance Often the result is a bad image. Therefore, for such an image having a poor gradation balance, a histogram (frequency distribution) of the gradation values of the image is analyzed to automatically expand the dynamic range, change the contrast,
Several automatic image correction methods for adjusting the balance of green and blue color components have been proposed.

FIG. 4 is a flowchart for explaining an example of a typical color tone correction method. Referring to FIG. 4, first, image data is sub-sampled and reduced to reduce the number of pixels to speed up the processing (step S1). next,
A frequency distribution (histogram) of gradation values for each color component of the image data is obtained (step S2). That is, when the image data is represented by red, green, and blue components, a red gradation value distribution, a green gradation value distribution, and a blue gradation value distribution are obtained. However, if the storage device for storing the frequency distribution creation result has a limited capacity, the frequency distribution of the gradation values may be obtained for only one color component. FIG. 5 shows an example of the luminance histogram obtained by the above processing.

Then, a predetermined characteristic amount is calculated from the histogram obtained in step S2, and it is determined whether or not the image data has an appropriate gradation characteristic. The correction parameters are determined and determined (steps S3, S4, S5). Here, the contents of the color tone correction processing generally include dynamic range correction, color balance correction, tone curve correction, and the like.

That is, in step S3, first, the white luminance and the black point luminance of the input image are obtained as feature amounts in order to determine whether or not the dynamic range is appropriately obtained. As the white luminance and the black point luminance, the maximum value and the minimum value of the input image are used.
Can be white brightness. If it is determined that the dynamic range is insufficient as a result of the determination of the dynamic range, a level correction process is performed to expand the dynamic range. Also, there is an example in which the expansion range of the dynamic range is limited so that a night scene image or the like is not converted more than necessary.

Next, in step S4, the color balance (color balance) is corrected so that the image having the color cast is determined and the color cast is removed. Various methods have been proposed for color cast correction. For example, since the color cast is conspicuous in a relatively bright part of the image, the RGB of the pixel with high luminance in the frequency distribution (histogram) is obtained.
Can be considered as a feature amount, a method of determining whether or not color fogging has occurred based on the amount of deviation from the feature amount (the average of RGB for high-brightness pixels) and determining the correction content. In this case, it is necessary to provide a parameter such as how much luminance should be checked or how much deviation should be determined to cause color cast.

For example, the color cast can be determined as follows. That is, when ΔR = Rave-Gave and ΔB = Bave-Gave, it is determined that the color is cast when ΔR> Rth and ΔB> Gth, and the R component and the B component are set so that ΔR and ΔB become 0. Perform gradation conversion. Where Ra
“ve”, “Gave”, and “Bave” are average values of R, G, and B components present in 10% from the brightest side of the histogram.

After the color balance (color balance) correction is performed, the exposure state is determined, and correction processing is performed as necessary. For example, when performing gradation conversion on an underexposed or overexposed image, the median or variance of the luminance value of the image data is obtained as a feature amount, and by determining these, it is determined whether the image is overexposed or underexposed. Generally, it can be determined. Other schemes can be used. Other shooting conditions (backlighting, flash photography, night photography, etc.)
In some cases, such as estimating a subject and estimating a subject from a feature amount of each block by dividing image data into small blocks.

If it is determined that the exposure situation requires correction, tone curve correction can be performed as in step S5. Tone curve correction can be realized by creating a correction tone curve and performing gamma correction using a simple look-up table as shown in FIG.

As described above, various color tone correction methods have been conventionally proposed. In each case, some characteristic amount is calculated from the image data, and the appropriateness of the gradation is determined based on the result to determine the correction content. A procedure to be determined will be performed.

As described above, in the first embodiment of the present invention, when the color space characteristic information of the RGB image data is described in the drawing data, the color tone correction processing is not performed. In addition, the color conversion processing can be executed at high speed, and the risk of performing unnecessary correction on an image for which color tone correction has already been performed can be reduced.

FIG. 7 shows an image processing apparatus 20 according to the first embodiment.
11 is a flowchart for describing an image processing method of No. 0. Referring to FIG. 7, first, in step S101,
The drawing data analysis unit 202 performs a process of detecting RGB color space characteristics. Next, in step S102, it is determined whether RGB color space characteristic information has been detected from the drawing data.

As a result, if the color space characteristic information cannot be detected, the process proceeds to step S103, and the process proceeds to step S1.
In step 03, the frequency distribution of gradation values for each color component is calculated from the image data. Next, in step S104, the above-described feature amounts (for example, white luminance and black point luminance) are calculated from the frequency distribution. Next, in step S105, step S1
The content (color tone correction processing method) for correcting the image data is determined based on the feature amount obtained in step 04. The correction contents include tone curve correction, dynamic range correction, and color balance correction as described above. Then, if it is determined what kind of color tone correction is to be performed, step S106
Thus, a color conversion parameter for realizing the color tone correction is generated.

On the other hand, if the color space characteristic information has been detected in step S102, the flow advances to step S107 to set the detected color space characteristic information as a color conversion parameter.

Then, color conversion processing is performed using the finally generated color conversion coefficients, and the result is output to the image output device 104.

As described above, in the first embodiment of the present invention, only when the drawing data analysis means 202 cannot extract the color space characteristic information of the RGB image data, the correction content determined by the correction content determination unit 303 is used. Since the color tone correction processing of the RGB image data is performed, the danger that unnecessary color tone correction processing is performed on image data created under sufficient color management can be reduced. At the same time, color correction is performed on low-quality image data for which strict color management is not performed.
A clear image with optimized contrast and color balance can be obtained.

As described above, in the first embodiment of the present invention, when the RGB color space characteristic information is included in the drawing data, the color reproduction is performed faithfully without performing the color tone correction processing. In this case, the risk of correcting an image that does not need to be corrected is reduced, but the possibility that the image that needs to be corrected is not corrected is also increased. For this reason, the user may feel dissatisfied because the correction effect is not so much seen in consumer applications.

Second Embodiment In a second embodiment of the present invention, in order to avoid the above-described problem in the first embodiment, the color tone correction is performed even when RGB color space characteristic information is detected in the drawing data. Is performed. However, in order not to apply excessive correction to the image data when the color space characteristic information is included,
In the color tone correction processing for image data when the color space characteristic information is included, the type of image to be corrected and the criterion for determining the feature amount are more limited than the color tone correction processing for image data that does not include the color space information. Like that.

FIG. 8 is a diagram showing a configuration example of the drawing data analysis means 202 and the image processing means 204 for images in the second embodiment. The image processing means 20 for images shown in FIG.
4 includes two types of feature value calculation units 410 and 420 that analyze image data to calculate a predetermined feature value, and determine what color tone correction is to be performed based on the calculated feature value (correction). Two types of correction content determination units 41 for determining the content
1, 421, a color conversion parameter setting unit 430 for realizing the correction content, and a color conversion processing unit 402. Here, the color conversion parameter setting unit 430 determines whether one of the two types of correction content determination units 411 and 412 depends on whether the drawing data analysis unit 202 has detected color space characteristic information from the drawing data. The color conversion parameters are generated in accordance with the correction contents determined by the correction content determination unit.

The two types of correction content decision sections 411, 4
When the same feature value is used by the reference number 21,
10, 420 may be common. That is, only one extra-quantity calculating unit (for example, 410) may be provided.

Next, the overall operation of the image processing means 204 for images according to the second embodiment will be described.

First, the drawing data analysis means 202 transmits information on whether or not the RGB color space characteristics have been detected from the drawing data to the color conversion parameter setting section 430. On the other hand, the image data part in the image drawing data is separated,
The information is sent to both of the feature amount calculation units 410 and 420.

The feature value calculation unit 410 receives the image data from the drawing data analysis unit 202, calculates a feature value for performing color tone correction, and provides the calculated feature value to the correction content determination unit 411. The correction content determination unit 411 determines how to correct the image data based on the feature value calculated by the feature value calculation unit 410 (that is, determines the correction content). When the correction content is determined by the correction content determination unit 411, the result is given to the color conversion parameter setting unit 430.

Similarly, the feature value calculation unit 420 receives the image data from the drawing data analysis unit 202, calculates a feature value for performing color tone correction, and provides the calculated feature value to the correction content determination unit 421. In the correction content determining unit 421,
It is determined how to correct the image data based on the feature amount calculated by the feature amount calculation unit 420 (that is, the content of the correction is determined). When the correction content is determined by the correction content determination unit 421, the result is given to the color conversion parameter setting unit 430.

The correction content determined by the correction content determining unit 411 and the correction content determined by the correction content determining unit 421 are different from each other as follows. That is,
As described later, the correction content determined by the correction content determination unit 411 is smaller than the correction content determined by the correction content determination unit 421 so that the range of change of the original data is suppressed. The type is limited, and the criterion for determining the feature amount is limited.

The color conversion parameter setting section 430 receives information on correction contents from the two types of correction content determination sections 411 and 421 and generates color conversion parameters for realizing correction. However, two types of correction content determination units 41
Which correction content of the two types of correction content from 421 and 421 is to be used to generate the color conversion parameter is controlled by the detection result of the color space characteristic information from the drawing data analysis means 202. That is, the color conversion parameter setting unit 430
Then, when the color space characteristic information is detected, the correction parameter for realizing the color tone determined by the feature amount calculation unit 410 and the correction content determination unit 411 and the detected color space characteristic information are subjected to color conversion. When the color space characteristic information is not detected, the characteristic amount calculation unit 42
0, a correction parameter for realizing the color tone correction determined by the correction content determination unit 421 and default color space characteristic information preset in the image processing unit 204 are provided to the color conversion processing unit 402.

The color conversion processing section 402 stores the correction parameters and the color conversion parameters such as color space characteristic information provided from the color conversion parameter setting section 430 with the RO in the apparatus in advance.
The color conversion process is performed using the color space characteristic information of the output device stored in M or the like.

Specifically, the color conversion processing unit 402 first
After performing gradation conversion such as dynamic range conversion, contrast conversion, and color balance conversion on the RGB image data according to the correction parameters, the RGB image data is converted into a standard signal using the RGB color space characteristic information. Next, the standard signal is converted into color data for an image output device (for example, a printer) using the color space characteristic information of the output device.

In the above-described color conversion processing, gradation conversion, standard signal conversion, and printer conversion are sequentially performed. Of course, first, the respective parameters are connected to input RGB image data and output to the color of the image output device (for example, a printer). The image data may be converted in one pass after parameters for converting the data are created.

Next, the color tone correction processing according to the second embodiment will be specifically described.

As described above, as typical color tone correction processing, correction processing such as dynamic range correction, color balance correction, and tone curve correction is performed, and it is determined whether these corrections are necessary. Various determination methods have been proposed. In general, the method differs depending on whether the correction is made positively or the correction is made so as not to change much from the original data.

In the second embodiment, the drawing data is
When the color space characteristic information is included, since the image data tends to be relatively color-managed image data, correction is performed so as not to change as much as possible from the original data. When the characteristic information is not included, aggressive color tone correction is performed.

More specifically, the feature quantity calculating section calculates, for example, the white luminance of the image from the frequency distribution (histogram) of the gradation values.
The black point luminance is obtained as a feature value.

The dynamic range is corrected based on the white luminance and black point luminance values of the image as feature amounts. At this time, the limit of the enlargement width is changed by the above-described two-system color tone correction. For example, the correction content determination unit 421 expands the dynamic range if the white luminance, which is the feature amount calculated by the feature amount calculation unit, is equal to or higher than level 200, and the correction content determination unit 411 sets the white brightness to level 240. In this case, the dynamic range is expanded.

By making the determination criteria of the characteristic values different in this way, even if the images have the same gradation distribution, the dynamic range is not largely corrected when the color space characteristic information is detected. be able to.

Similarly, in the correction of the color balance, the correction range can be limited by changing the determination level of the color cast. When the color space characteristic information is detected, the color balance correction itself may not be performed, and the color balance correction may be performed only when the color space characteristic information is not detected.

In the case of the tone curve correction, the correction parameter can be controlled by changing the correction width obtained from the median value and the variance value of the luminance value of the image data. The correction may be performed only in a specific shooting situation.

For example, if color space characteristic information is detected as a result of the photographing situation determination, correction is performed only for a backlight scene as an image type, and when color space characteristic information is not detected, image correction is performed. As the type of image, correction can be performed for images other than backlight, such as daytime, night view, and indoor images.

Further, as a typical method of color tone correction, there is a method of performing more advanced color tone correction by analyzing an image for each small block and estimating a portion where a subject is photographed. However, such subject estimation tends to cause an estimation error, so that a large improvement effect can be obtained. However, there is a risk that image quality is deteriorated in some images. Therefore, when the color space characteristic information is detected, the color tone is corrected based on the overall brightness information without subject estimation, and only when the color space characteristic information is not detected,
The subject may be estimated to perform dynamic color tone correction.

FIG. 9 is a flowchart for explaining an image processing method of the image processing apparatus 200 according to the second embodiment.

Referring to FIG. 9, first, at step S20
In step 1, the drawing data analysis unit 202 performs a process of detecting RGB color space characteristics. Next, in step S202, it is determined whether RGB color space characteristic information has been detected.

As a result, when the color space characteristic information cannot be detected, the process proceeds to step S203, and the process proceeds to step S2.
In step 03, a frequency distribution of gradation values for each color component is calculated from the image data. Next, in step S204, the above-described feature amounts (for example, white luminance and black point luminance) are calculated from the frequency distribution. Next, in step S205, the content for correcting the image data is determined based on the feature amount obtained in step S204. As described above, the correction contents include tone curve correction, dynamic range correction, color balance correction, and the like. Then, when it is determined what kind of color correction is to be performed, a color conversion parameter for realizing the color correction is generated in step S206.

On the other hand, if the color space characteristic information is detected in step S202, color conversion parameters are set by performing color tone correction processing different from steps S203 to S206 (steps S207 to S21).
0). That is, in step S207, a frequency distribution of gradation values for each color component is calculated from the image data. Next, in step S208, the above-described feature amounts (for example, white luminance and black point luminance) are calculated from the frequency distribution. Next, based on the feature amount obtained in step S208, step S20
In step 9, contents for correcting the image data are determined. At this time, the content of the correction is limited to the content of the correction determined in step S205. Then, if it is determined what kind of color tone correction is to be performed, step S210
Thus, a color conversion parameter for realizing the color tone correction is generated.

Of course, the frequency distribution used in step 204 and the frequency distribution used in step S208 may be the same, and the feature amounts calculated in steps S204 and S208 may be the same.

As described above, in the second embodiment of the present invention, the case where the color space characteristic information of the RGB image data can be extracted by the drawing data analysis means and the case where the color space characteristic information of the RGB image data cannot be extracted are Since different correction contents are selected from among a plurality of types of correction contents and different color tone correction processes are performed on the RGB image data, it is possible to correct the color tone suitable for the attribute of the drawing data. .

Third Embodiment In this type of image processing system, RGB image data captured by an image input device (such as a digital camera or a scanner) is added with profile information of the image input device and rendered. When color correction is performed on the RGB image data, profile information of the image display device performing the correction is added to the RGB image data and stored as drawing data. become.

In the third embodiment of the present invention, the color tone correction processing is controlled in accordance with the type of image generating device (image input device or image display device) added to the drawing data as described above. Has become. That is, in the third embodiment, when the type of the image generation device is the image input device, it is considered that the color correction work has not been performed on the RGB image data, while the type of the image generation device is the image input device. In the case of a display device (for example, a display), attention is paid to the fact that it is highly likely that the user has already performed color correction work on the RGB image data while looking at the image display device.

Focusing on the above points, in the third embodiment of the present invention, in the configuration example of FIG.
02 has a function of detecting, from the drawing data, the type of the image generating apparatus that has generated the RGB image data. The feature amount calculation unit 302 obtains a predetermined feature amount from the RGB image data, and the correction content determination unit 303 The correction content of the RGB image data is determined using the feature amount calculated by the feature amount calculation unit 302, and the color conversion parameter setting unit 304 determines, based on the type of the image generation device obtained by the drawing data analysis unit 202, The color conversion parameters used for the color conversion processing are controlled.

In other words, in the third embodiment of the present invention, the color conversion parameter setting unit 304 and the color conversion processing unit 30
Reference numeral 5 switches whether or not to perform the color tone correction processing of the RGB image data with the correction content determined by the correction content determination unit 303 according to the type of the image generation device detected by the drawing data analysis unit 202. ing.

Next, the overall operation of the drawing data analyzing means 202 and the image processing means 204 in the third embodiment will be described.

First, the drawing data analysis means 202 detects and reads profile information describing attributes of RGB signals and the like from the image drawing data.

For example, in a bitmap format which is a standard image data format of the Windows operating system, an ICC profile corresponding to a header portion of image data can be described to define a color attribute of the image data.

FIG. 10 shows the data format of the ICC profile. The ICC profile has been standardized in a data format as shown in FIG. 10, and is frequently used in various scenes in recent years. As shown in FIG. 10, the ICC profile includes a header portion, a Tag table indicating a position where Tag data exists, and Tag data (substantial portion of Tag data). In the header portion, in addition to the name of CMM (color conversion engine) to be used, the type of device, and the type of standard signal, the type of profile is described. This profile type is
Code data of the image generating apparatus that generates image data is described as "scnr" if the image generating apparatus is a scanner, and "mntr" if the image generating apparatus is an image display apparatus (display). ing.

The Tag portion (Tag table, Tag
g data), various additional data related to color conversion can be set in detail as necessary, and color conversion parameters for converting device signals to standard signals such as XYZ signals and Lab signals are also provided. It is described as Tag data.

As described above, by controlling the color conversion processing with reference to the information of the image generation device (the image generation device that has generated the RGB image data) described in the header portion of the image data, the image conversion device is more suitable for an image. Color reproduction can be realized.

That is, the drawing data analysis means 202
When a profile is detected from the drawing data, the profile information is provided to the color conversion parameter setting unit 304. On the other hand, when the profile is not described in the drawing data, a code indicating that the profile is not defined is given to the color conversion parameter setting unit 304. Further, the image data portion in the image drawing data is separated and sent to the feature amount calculation unit 302 and the color conversion processing unit 305.

A color conversion processing unit 305 uses a color conversion parameter for converting an input RGB signal into a standard color signal and a color conversion parameter for converting a standard color signal into a color signal of an output device. And do
As each color conversion parameter, the one set in the color conversion parameter setting unit 304 is used. For specific color conversion processing, masking conversion, memory map interpolation, or the like can be used, and there is no particular limitation.

The color conversion parameter setting unit 304 receives the input R
An input device color conversion parameter for converting a GB signal into a standard signal and an output device color conversion parameter for converting a standard signal into an output device color signal are set. The color conversion parameters for input are the profile information from the drawing data analysis unit 202 and the correction content determination unit 3.
It is generated as a parameter suitable for the image data using the correction parameter determined in step S03. As the color conversion parameter for the output device, a parameter registered in the image output device in advance is used (for example, when the image output device is a printer, an image output is previously performed by inquiring of a printer driver or the like). Use the parameters registered in the device).

FIG. 11 is a flowchart for explaining the operation of setting the input color conversion parameters in the color conversion parameter setting section 304. Referring to FIG. 11, first, it is determined whether or not profile information has been received from the drawing data analysis unit 202 (step S301). As a result, when profile information is not received (for example, when a code with an undefined profile is received), the color conversion parameter setting unit 304 proceeds to step S30.
At 3, the color conversion parameters are set, for example, in a parameter storage memory (not shown). In this case, since the color space characteristics of the input RGB signals are unknown, a default color conversion parameter is read from a ROM or the like as a color conversion parameter and set.

If no profile is defined and input RG
An image whose color space characteristic of the B signal is unknown is image data for which strict color management has not been performed. Therefore, there is a high possibility that an appropriate color tone will not be obtained even if color conversion is performed using default color conversion parameters. Therefore, in this case, the color conversion parameter setting unit 304 includes the feature amount calculation unit 302 and the correction content determination unit 3
03 (Step S)
306), the color conversion parameters set in the parameter storage memory are updated using the correction contents (step S307). Then, the color conversion processing unit 305 performs color tone correction processing and color conversion processing based on the updated color conversion parameters. That is, when the image generation device cannot be determined, the color conversion parameter setting unit 304 and the color conversion processing unit 305 perform a color tone correction process for correcting at least one of the dynamic range, the tone curve, and the color balance of the image data.

On the other hand, if it is determined in step S301 that the profile information has been received, the color conversion parameter setting unit 304 reads the color space characteristic information of the RGB signal described in the profile, and It is set (step S302). That is, R
When the conversion from the GB signal to the XYZ signal is performed by the matrix operation, the coefficient of the matrix operation is set. When the conversion is performed by the memory map interpolation operation, the parameter of the interpolation operation is set as the color conversion parameter.

Next, in step S304, the profile type is read, and in step S305, whether the profile type indicates an image input device (for example, a scanner) or an image display device (for example, a display) Is determined. For example, when the profile type is “scnr”, since the image data is input by the image input device, it can be considered that the color tone has not been corrected. Output to an image output device, there is a high possibility that the image quality can be improved. On the other hand, when the profile type indicates the image display device (in this case, the profile type is “mntr”), the profile is created by an application on a PC (personal computer) or input by an image input device. Since the image has been changed / saved by color correction, it is considered that it is preferable for the operator to faithfully reproduce the RGB signal.

That is, if it is determined in step S305 that the image has been created on the image display device, the flow advances to step S308 to cause the color conversion processing unit 305 to perform color conversion processing. That is, in this case, the color conversion processing unit 305
Realizes colorimetrically accurate color reproduction by performing color conversion using the color conversion parameters set in step S302 as they are. That is, when the image generation device is an image display device, the color conversion processing unit 305 uses the color space characteristics of the image display device and the color space characteristics of the image output device so that the colorimetric values match. Perform conversion processing.

If it is determined in step S 305 that the image data is image data input by the image input device, the color conversion parameter setting unit 304 determines whether the feature amount calculation unit 302 and the correction content determination unit 303 have the same. Using the determined correction contents, the color conversion parameters are updated in the same manner as when no profile is included (step S
306, S307). Thereby, the color conversion processing unit 305
Can perform color conversion by correcting (improving) the color tone of image data. That is, when the image generation device is an image input device, the color conversion processing unit 305 performs a color tone correction process for correcting at least one of the dynamic range, the tone curve, and the color balance of the image data.

As described above, in the third embodiment, the color profile is not described in the drawing data, or the type of the device described in the profile is fetched from an image input device such as a scanner or a digital camera. If it means that the data is image data, the feature amount calculation unit 302 and the correction content determination unit 303 are operated to generate color conversion parameters for performing color tone correction, perform color tone correction processing, and generate a profile. If the described device type is an image display device such as a display, the color tone correction process is not performed.

As described above, in the image processing system according to the third embodiment of the present invention, it can be determined that the operator is viewing the RGB image data on the image display device, and the characteristics of the image display device are known. Only in the case of, the color correction processing is not performed, so that the color conversion processing can be performed at high speed and the danger of performing unnecessary correction on an image for which the color correction has already been performed. Can be reduced.

FIG. 12 is a flowchart for explaining an image processing method of the image processing apparatus 200 according to the third embodiment. Referring to FIG. 12, first, step S401
Then, it is determined whether color tone correction is necessary based on the drawing data. Whether or not the color tone correction is necessary is determined based on whether or not the image generation device that has generated the image data is an image display device, as described with reference to FIG. In step S401,
If it is determined that color tone correction is necessary, first, in step S402, a frequency distribution of tone values for each color component is calculated from the image data. Next, in step S403, the above-described feature amount (for example, white luminance, black point luminance) is calculated from the frequency distribution.
Is calculated. Next, in step S404, step S404
The content for correcting the image data is determined based on the feature amount obtained in 403 (the processing method of color tone correction is set). As described above, the correction contents include tone curve correction, dynamic range correction, color balance correction, and the like. When it is determined what kind of color tone correction is to be performed (when the correction content is determined), in step S405, a color conversion parameter for realizing the color tone correction is generated.

On the other hand, if the RGB color space characteristics of the image display device are detected in the drawing data in step S401, it is determined that the color tone correction is not necessary, so the process proceeds to step S406, where the detected RGB color space is detected. The characteristic information is set in the color conversion parameter.

Then, color conversion processing is performed using the finally generated color conversion coefficients, and the result is output to the image output device 104.

With the above method, the risk of unnecessary color tone correction processing being performed on image data created on a PC (personal computer) or color-corrected can be reduced. By performing color tone correction processing on low-quality image data that has not been color-corrected, a clear image with optimized contrast and color balance can be obtained.

Fourth Embodiment In the above-described third embodiment, the drawing data is analyzed, and when the RGB image data is input by the image input device and when the RGB color space characteristic information is unknown. Is
A similar color tone correction process was performed. But R
If an image whose GB color space characteristic information is unknown (for example, an image created by a PC (personal computer)) is subjected to the same color tone correction processing as an image input by the image input device, inappropriate There is a risk that correction will be made.

Therefore, in the fourth embodiment, different color tone corrections are performed when the RGB color space characteristic information of the image data is not defined and when the color space characteristics of the image input device are clearly defined. To be applied. That is, RG
When the B color space characteristic information is not defined, the type and correction of the image to be corrected are compared with the case where the color space characteristic of the image input device is clearly defined so that excessive correction is not applied. The criterion for determining the target feature amount is limited.

The construction of the image processing means 204 for images in the fourth embodiment is basically the same as that shown in FIG.

Next, the overall operation of the image processing means 204 according to the fourth embodiment will be described.

That is, first, the drawing data analysis means 20
2 transmits to the color conversion parameter setting unit 430 information on whether or not the RGB color space characteristics have been detected from the drawing data.
On the other hand, a part of the image data in the image drawing data is separated and sent to both of the feature amount calculation units 410 and 420.

The feature value calculation unit 410 receives the image data from the drawing data analysis unit 202, calculates a feature value for performing color tone correction, and provides the calculated feature value to the correction content determination unit 411. The correction content determination unit 411 determines how to correct the image data based on the feature value calculated by the feature value calculation unit 410 (that is, determines the correction content). When the correction content is determined by the correction content determination unit 411, the result is given to the color conversion parameter setting unit 430.

Similarly, the feature value calculation unit 420 receives the image data from the drawing data analysis unit 202, calculates a feature value for performing color tone correction, and provides the calculated feature value to the correction content determination unit 421. In the correction content determining unit 421,
It is determined how to correct the image data based on the feature amount calculated by the feature amount calculation unit 420 (that is, the content of the correction is determined). When the correction content is determined by the correction content determination unit 421, the result is given to the color conversion parameter setting unit 430.

The color conversion parameter setting section 430 receives information on correction contents from the two types of correction content determination sections 411 and 421, and generates color conversion parameters for realizing correction. However, two types of correction content determination units 41
Which correction content of the two types of correction content from 421 and 421 is to be used to generate the color conversion parameter is controlled by the content of the profile information from the drawing data analysis means 202.

That is, when a code indicating that the profile is undefined is received from the drawing data analysis means 202, the color conversion parameter setting section 430 determines the feature by the feature quantity calculation section 420 and the correction content determination section 421. The correction parameter for realizing the obtained color tone correction and the default color space characteristic preset in the image processing apparatus 200 are provided to the color conversion processing unit 402 as the color conversion parameter for the input signal.

On the other hand, when the profile information from the drawing data analysis means 202 is the RGB signal of the image input device, the color conversion parameter setting section 430 is determined by the feature amount calculation section 410 and the correction content determination section 411. A correction parameter for realizing color tone correction and RGB color space characteristic information of the image input device described in the profile information are provided to the color conversion processing unit 402 as color conversion parameters for an input signal.

When the profile information from the drawing data analysis means 202 is an RGB signal of the image display device, the color conversion parameter setting section 430 sets the RGB color space characteristics of the image input device described in the profile information. Information is provided to the color conversion processing unit 402 as a color conversion parameter for an input signal.

The color conversion processing unit 402 is provided with a color conversion parameter such as a correction parameter and a color space characteristic provided from the color conversion parameter setting unit 430 and color space characteristic information of an output device which is recorded in advance in a ROM or the like in the apparatus. Is used to perform color conversion processing.

More specifically, first, the color conversion processing unit 402
After performing gradation conversion such as dynamic range conversion, contrast conversion, and color balance conversion on the RGB image data according to the correction parameters, the RGB image data is converted into a standard signal using the RGB color space characteristic information. Next, the standard signal is converted into color data for the image output device (for example, a printer) 104 using the color space characteristic information of the output device.

In the above-described color conversion processing, gradation conversion, standard signal conversion, and printer conversion are performed in this order. Of course, the input RGB image data is first connected to convert the input RGB image data into the color of an image output device (eg, a printer). The image data may be converted in one pass after parameters for converting the data are created.

As described above, in the fourth embodiment, different color tone correction processing is performed depending on the case where the RGB color space information of the image data is not defined or the type of the image generating apparatus.

Next, the tone correction processing in the fourth embodiment will be specifically described.

As described above, as typical color tone correction processing, correction processing such as dynamic range correction, color balance correction, and tone curve correction is performed. However, it is determined whether these corrections are necessary. Various determination methods have been proposed. In general, the method differs depending on whether the correction is made positively or the correction is made so as not to change much from the original data.

In the fourth embodiment, when it is not clear which image generating device is used to generate image data, a correction is made so that the image data does not greatly change from the original data. If it is clear that the image is an input image, aggressive color tone correction is performed.

More specifically, first, white luminance and black point luminance of an image are obtained from the frequency distribution (histogram) of gradation values as feature amounts. The dynamic range is corrected based on these values. At this time, the limit of the enlargement width is changed by the above-described two-system color tone correction. For example, the correction content determination unit 421
It is assumed that if the white luminance is at least level 200, the dynamic range is expanded, and the correction content determination unit 411
In this case, if the white luminance is equal to or higher than the level 240, the dynamic range is expanded.

By making such a determination, it is possible to prevent the dynamic range from being greatly corrected when color space characteristic information is detected, even for images having the same gradation distribution.

Similarly, in the color balance correction, the correction width can be limited by changing the color cast determination level. When the RGB color space characteristic information is not defined, the color balance correction itself is not performed, and the color balance correction is performed only when it is clear that the image data is obtained by the image input device. Is also good.

In the case of the tone curve correction, the correction parameters can be controlled by changing the correction width obtained from the median value and the variance of the luminance value of the image data, and further, the photographing state can be estimated. The correction may be performed only in a specific shooting situation.

For example, as a result of judging the photographing situation, RGB
When the color space characteristic information is not defined, the correction is performed only for the backlight scene as the image type,
When it is clear that the image data is image data obtained by the image input device, it is possible to perform correction on images of daytime, night view, indoors, etc. other than the backlight as the image type.

FIG. 13 is a flowchart for explaining an image processing method of the image processing apparatus 200 according to the fourth embodiment.

Referring to FIG. 13, first, at step S5
In step 01, it is determined whether or not the image data includes color signal attribute information such as a profile (whether or not the color signal attribute information has been detected). As a result, if the color signal attribute information has been detected, the process proceeds to step S502.

In step S502, the color signal attribute information is read to determine whether the source of the image data is an image input device or an image display device. As a result, when it is determined that the generation source of the image data is the image display device, step S
In step S511, RGB color space characteristics described in color signal attribute information such as an ICC profile are read, and color conversion parameters are set using the read color space characteristics.

In contrast, in step S502,
If it is determined that the source of the image data is the image input device, the color conversion parameters are set by executing the color tone correction processing of steps S503 to S505. That is, first, in step S503, a frequency distribution of gradation values for each color component is calculated from the image data. Next, in step S504, the above-described feature amount (for example, white luminance,
Black point luminance). Next, in step S505,
The content for correcting the image data is determined based on the feature amount obtained in step S504. As described above, the correction contents include tone curve correction, dynamic range correction,
For example, color balance correction.

If it is determined what kind of color tone correction is to be performed (if the correction content is determined), step S506 is performed.
Thus, a color conversion parameter for realizing the color tone correction is generated.

On the other hand, if the color signal attribute information cannot be detected in step S501, the process proceeds to step S507.
In steps S509 to S509, color conversion parameters different from those in steps S503 to S505 are set to set color conversion parameters. That is, in step S507, the frequency distribution of the gradation values for each color component is calculated from the image data. Next, in step S508, the above-described feature amounts (for example, white luminance and black point luminance) are calculated from the frequency distribution. Next, in step S509, the content for correcting the image data is determined based on the feature amount obtained in step S508. The correction content is set to a content that is more limited than the correction content determined in step S505.

When it is determined what kind of color tone correction is to be performed (if the correction content is determined), step S510 is performed.
Thus, a color conversion parameter for realizing the color tone correction is generated.

In the above processing, step S50
Color tone correction processing of 3 to S505 and steps S507 to S507
If the frequency distribution and the feature amount used in the color tone correction processing in step 509 can be shared, they can be shared.

As described above, in the fourth embodiment of the present invention, the case where the RGB color space characteristic information of the image data is not defined and the case where the color space characteristic of the image input device is clearly defined. Since different color tone corrections are performed, appropriate color tone correction according to each case can be performed.

FIG. 14 is a diagram showing an example of the hardware configuration of the image processing system shown in FIGS. Referring to FIG. 14, this image processing system is realized by, for example, a workstation or a personal computer, and is used as a CPU 21 for controlling the whole, a ROM 22 storing a control program of the CPU 21, and a work area of the CPU 21. RAM 23 and hard disk 24
And a digital camera 101 and a scanner 102 for inputting RGB image data, a display 100 for displaying image data, and an image output device 104 such as a color printer.

Here, CPU 21, ROM 22, RAM
23 and the hard disk 24 have a function as the computer 103 in FIGS. In this case,
The functions of the image processing apparatus 200 shown in FIGS.
Can be given.

The function as such an image processing device in the CPU 21 can be provided, for example, in the form of a software package (specifically, an information recording medium such as a CD-ROM). In the example, when the information recording medium 30 is set, a medium driving device 31 that drives the information recording medium 30 is provided.

In other words, the image processing system of the present invention causes a general-purpose computer system having an image scanner, a display, and the like to read a program recorded on an information recording medium such as a CD-ROM, and It is also possible to implement the present invention in an apparatus configuration in which a microprocessor executes image processing. in this case,
A program for executing the image processing of the present invention (that is, a program used in a hardware system)
Is provided in a state recorded on a medium. The information recording medium on which the program or the like is recorded is not limited to a CD-ROM, but may be a ROM, a RAM, a flexible disk, a memory card, or the like. The program recorded on the medium is installed in a storage device incorporated in the hardware system, for example, the hard disk 24, so that the program can be executed to realize an image processing function.

A program for realizing the image processing system of the present invention may be provided not only in the form of a medium but also by communication (for example, by a server).

The present invention also relates to an image recording apparatus for transmitting an input color image signal such as image data obtained by reading a photographic film or image data obtained from a digital camera to an image output device such as a color printer. It can be applied to image processing devices that convert to signals, driver software for color printers, image editing software, and web browsing applications.

[0165]

As described above, according to the first, second, fourth, eighth and tenth aspects of the present invention, drawing data including RGB image data is received.
In an image processing system having a function of correcting a color tone of RGB image data included in drawing data and outputting the corrected color tone to an image output device, a drawing data analyzing means for extracting color space characteristic information of RGB image data from the drawing data A feature value calculating means for obtaining a predetermined feature value from the RGB image data; a correction content determining means for determining the correction content of the RGB image data using the feature value calculated by the feature value calculating means; Processing means, wherein the color conversion processing means uses the correction content determined by the correction content determination means only when the drawing data analysis means cannot extract the color space characteristic information of the RGB image data.
Since the color tone correction processing of the image data is performed, the risk that unnecessary correction processing is performed on an image that requires accurate color reproduction can be avoided.

In particular, according to the second aspect of the present invention, in the image processing system according to the first aspect, the color conversion processing means is provided when the color space characteristics of the RGB image data can be extracted by the drawing data analysis means. Performs color conversion processing using the color space characteristics of the RGB image data and the color space characteristics of the image output device so that the colorimetric values match, so that both desirable color reproduction and faithful color reproduction can be achieved. .

Further, claims 3 to 7, claim 9,
According to the eleventh aspect of the present invention, drawing data including RGB image data is received, and R included in the drawing data is received.
In an image processing system having a function of correcting a color tone of GB image data and outputting the corrected color tone to an image output device, a drawing data analyzing unit for extracting color space characteristic information of RGB image data from the drawing data, Feature value calculating means for obtaining a predetermined feature value; correction content determining means for determining a plurality of types of correction content for the RGB image data using the feature value calculated by the feature value calculating means;
Color conversion processing means, wherein the color conversion processing means determines whether or not the drawing data analysis means can extract the color space characteristic information of the RGB image data and when the color space characteristic information of the RGB image data cannot be extracted. Since different correction contents are selected from among the types of correction contents and different color tone correction processes are performed on the RGB image data, it is possible to correct the color tone suitable for the attribute of the drawing data.

According to the fourth aspect of the present invention, in the image processing system according to the first or third aspect,
Since the color conversion processing means performs at least one of a dynamic range, a tone curve, and a color balance of the image data, the color conversion processing means performs the color tone correction processing.
It is possible to appropriately correct an image in which the AE does not function well, the flash light does not illuminate the subject well when photographing with a digital camera, or the flash does not emit light when the subject is backlit.

According to a fifth aspect of the present invention, in the image processing system according to the third aspect, when the color space characteristics of the RGB image data can be extracted by the drawing data analysis means, the color of the RGB image data can be extracted. Since the type of image to be corrected is limited as the content of the correction as compared with the case where the spatial characteristics cannot be extracted, the necessity of correction can be accurately determined according to the description content of the drawing data.

According to a sixth aspect of the present invention, in the image processing system according to the third aspect, when the color space characteristics of the RGB image data can be extracted by the drawing data analysis means, the color of the RGB image data can be extracted. As compared with the case where the spatial characteristics cannot be extracted, the criterion for determining the feature amount to be corrected is limited as the correction content. So, according to the description contents of the drawing data,
The correction amount can be set appropriately.

According to the invention of claim 7, in the image processing system of claim 3, if the color space characteristics of the RGB image data cannot be extracted by the drawing data analyzing means, the image data is used. The brightness of the subject is determined to determine the content of the correction, and the color content correction processing of the RGB image data is performed based on the correction content. If the color space characteristics of the RGB image data can be extracted, the brightness of the entire image is determined. Since the correction content is determined by the correction and the color correction process of the RGB image data is performed using the correction content, it is possible to reduce the deterioration of the image quality due to the estimation error of the subject with respect to the image which is unlikely to require the color tone correction.

According to the twelfth aspect of the present invention, the type of the image generating device that has generated the RGB image data is read from the drawing data, and the RGB image data is read in accordance with the type of the read image generating device. Since it is switched whether or not to correct the color tone of the data, it is possible to avoid the risk of performing unnecessary correction processing on an image that requires accurate color reproduction.

In particular, according to the invention of claim 13, in the image processing system of claim 12, when the image generation device is an image display device, the color conversion processing means performs a color tone correction process. Instead, a color conversion process is performed using the color space characteristics of the image display device and the color space characteristics of the image output device so that the colorimetric values match, and thereby, for example, creation / correction on a computer It is possible to prevent the changed image from being changed carelessly.

According to the fourteenth aspect of the present invention, in the image processing system according to the twelfth aspect, when the image generation device is an image input device, the color conversion processing means includes a correction content determination means. At least the dynamic range of the image data,
A color tone correction process for correcting any one of the tone curve and the color balance is performed, and an image that has not been subjected to color correction can be specified and appropriate color correction can be automatically performed.

According to a fifteenth aspect of the present invention, in the image processing system according to the twelfth aspect, when the image generation device cannot be determined, the color conversion processing means is determined by the correction content determining means. In accordance with the correction content, at least one of the dynamic range, the tone curve, and the color balance of the image data is corrected, so that, for example, a color signal assumed by the image output device is corrected. Even when image data having different color space characteristics is input, appropriate color correction can be automatically performed.

According to the sixteenth aspect of the present invention, in the image processing system according to the twelfth aspect, when the image generation device is not defined, the image generation device is an image input device. In comparison, since the color tone correction processing is performed by limiting the type of image to be corrected, the necessity of correction can be accurately determined according to the description content of the drawing data.

According to the seventeenth aspect of the present invention, in the image processing system according to the twelfth aspect, when the image generation device is not defined, the image generation device is an image input device. On the other hand, since the color tone correction process is performed by limiting the criterion of the feature amount to be corrected, the correction amount can be appropriately set according to the description content of the drawing data.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an image processing system according to the present invention.

FIG. 2 is a diagram for explaining processing functions of a computer and an image processing device in the image processing system of FIG. 1;

FIG. 3 is a diagram illustrating a configuration example of a drawing data analysis unit and an image image processing unit according to the first and third embodiments of the present invention.

FIG. 4 is a flowchart for explaining an example of a typical color tone correction method.

FIG. 5 is a diagram illustrating an example of a luminance histogram.

FIG. 6 is a diagram showing a lookup table.

FIG. 7 is a flowchart illustrating an image processing method of the image processing apparatus according to the first embodiment.

FIG. 8 is a diagram showing a configuration example of a drawing data analysis unit and an image image processing unit according to the second and fourth embodiments of the present invention.

FIG. 9 is a flowchart illustrating an image processing method of the image processing apparatus according to the second embodiment.

FIG. 10 is a diagram showing a data format of an ICC profile.

FIG. 11 is a flowchart illustrating an operation of setting a color conversion parameter for input in a color conversion parameter setting unit.

FIG. 12 is a flowchart illustrating an image processing method of the image processing apparatus according to the third embodiment.

FIG. 13 is a flowchart illustrating an image processing method of the image processing apparatus according to the fourth embodiment.

FIG. 14 is a diagram illustrating an example of a hardware configuration of an image processing system according to the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 display 101 digital camera 102 scanner 103 computer 104 image output device 200 image processing device 201 buffer memory 202 drawing data analysis means 203 graphics image processing means 204 image image processing means 205 text image processing means 206 raster image generation means 207 Transmission data generation means 302 Feature amount calculation unit 303 Correction content determination unit 304 Color conversion parameter setting unit 305 Color conversion processing unit 410, 420 Feature amount calculation units 411, 412 Correction content determination unit 430 Color conversion parameter setting unit 402 Color conversion processing unit 21 CPU 22 ROM 23 RAM 24 Hard Disk 30 Information Storage Medium 31 Medium Drive

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5B021 AA01 LG07 5B057 CA01 CA08 CA12 CA16 CB01 CB06 CB12 CB16 CC01 CE11 CE17 CH07 5C077 LL19 MP08 PP31 PP32 PP37 PP66 PQ08 PQ19 5C079 HB01 LA01 LA12 LA23 LA31 LB02 NA02

Claims (21)

[Claims] 1. An image processing system having a function of receiving drawing data including RGB image data, correcting the color tone of the RGB image data included in the drawing data, and outputting the corrected data to an image output device. Drawing data analysis means for extracting color space characteristic information of the RGB image data, feature quantity calculation means for obtaining a predetermined feature quantity from the RGB image data, and the RGB image using the feature quantity calculated by the feature quantity calculation means A correction content determining unit for determining the correction content of the data; and a color conversion processing unit.
An image processing system comprising: performing color tone correction processing of RGB image data with the correction content determined by the correction content determination means only when color space characteristic information of B image data cannot be extracted. 2. The image processing system according to claim 1, wherein the color conversion processing unit determines a color space characteristic of the RGB image data if the drawing data analysis unit can extract a color space characteristic of the RGB image data. An image processing system that performs a color conversion process using a color space characteristic of an image output device so that colorimetric values match. 3. An image processing system having a function of receiving drawing data including RGB image data, correcting the color tone of the RGB image data included in the drawing data, and outputting the corrected data to an image output device. Drawing data analysis means for extracting color space characteristic information of the RGB image data, feature quantity calculation means for obtaining a predetermined feature quantity from the RGB image data, and the RGB image using the feature quantity calculated by the feature quantity calculation means A correction content determining means for determining a plurality of types of correction content for the data; and a color conversion processing means, wherein the color conversion processing means can extract color space characteristic information of the RGB image data by the drawing data analysis means. When the color space characteristic information of the RGB image data cannot be extracted, different correction contents are selected from among a plurality of types of correction contents. An image processing system for performing different color tone correction processing on RGB image data. 4. The image processing system according to claim 1, wherein said color conversion processing means performs color tone correction processing for correcting at least one of a dynamic range, a tone curve, and a color balance of the image data. An image processing system, comprising: 5. The image processing system according to claim 3, wherein when the color space characteristics of the RGB image data can be extracted by the drawing data analyzing means, the color space characteristics of the RGB image data cannot be extracted. An image processing system wherein the type of image to be corrected is limited as the correction content. 6. The image processing system according to claim 3, wherein when the drawing data analysis means can extract the color space characteristics of the RGB image data, compared to when the color space characteristics of the RGB image data cannot be extracted. An image processing system characterized in that, as correction contents, a criterion for determining a feature amount to be corrected is limited. 7. The image processing system according to claim 3, wherein when the drawing data analysis means cannot extract the color space characteristics of the RGB image data, the brightness of the subject is determined using the image data and the correction content is determined. Is determined, and a color tone correction process is performed on the RGB image data with the correction contents.
When the color space characteristics of the GB image data can be extracted, the brightness of the entire image is determined to determine the correction content, and the correction content performs the color tone correction process of the RGB image data. . 8. An image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected image data to an image output device, wherein the drawing data includes color space characteristic information of the RGB image data. If color space characteristic information is not included, a predetermined characteristic amount is obtained from the RGB image data, and color tone correction of the RGB image data is performed using the predetermined characteristic amount. An image processing method characterized by the following. 9. An image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected image data to an image output device, wherein the drawing data includes color space characteristic information of the RGB image data. And if the color space characteristic information is included,
An image processing method comprising performing color tone correction with a limited correction range as compared with a case where color space characteristic information is not included. 10. When receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected data to an image output device, whether the drawing data includes color space characteristic information of the RGB image data. It is determined whether the color space characteristic information is not included, and if the color space characteristic information is not included, a predetermined feature amount is obtained from the RGB image data, and the color tone correction of the RGB image data is performed using the predetermined feature amount. A computer-readable recording medium recording a program to be executed by a computer. 11. When receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected image data to an image output device, whether the drawing data includes color space characteristic information of the RGB image data. A program for causing a computer to execute a process of performing color tone correction with a limited correction range when color space characteristic information is included, as compared with a case where color space characteristic information is not included. A computer-readable recording medium on which is recorded. 12. An image processing system having a function of receiving drawing data including RGB image data, correcting the color tone of the RGB image data included in the drawing data, and outputting the corrected RGB image data to an image output device. A drawing data analyzing unit that detects a type of the generated image generating apparatus from the drawing data; a feature amount calculating unit that obtains a predetermined feature amount from the RGB image data; and a feature amount calculated by the feature amount calculating unit. A correction content determining unit for determining the correction content of the RGB image data; and a color conversion processing unit, wherein the color conversion processing unit corrects the correction content in accordance with the type of the image generating apparatus detected by the drawing data analysis unit. It is characterized by switching whether or not to perform the color tone correction processing of the RGB image data according to the correction contents determined by the determining means. Image processing system. 13. The image processing system according to claim 12, wherein when the image generation device is an image display device, the color conversion processing unit does not perform a color tone correction process.
An image processing system that performs a color conversion process using a color space characteristic of an image display device and a color space characteristic of an image output device so that colorimetric values match. 14. The image processing system according to claim 12, wherein when the image generation device is an image input device, the color conversion processing means determines at least an image according to the correction content determined by the correction content determination means. An image processing system for performing a color tone correction process for correcting any one of a dynamic range, a tone curve, and a color balance of data. 15. The image processing system according to claim 12, wherein when the image generation device cannot be determined, the color conversion processing unit determines at least dynamic image data according to the correction content determined by the correction content determination unit. An image processing system for performing a color tone correction process for correcting any one of a range, a tone curve, and a color balance. 16. The image processing system according to claim 12, wherein when the image generation device is not defined, the type of the image to be corrected is smaller than when the image generation device is an image input device. An image processing system characterized in that a color tone correction process is performed by limiting the color tone. 17. The image processing system according to claim 12, wherein when the image generation device is not defined, the feature amount to be corrected is smaller than when the image generation device is an image input device. An image processing system wherein a color tone correction process is performed by limiting a reference. 18. An image processing method for receiving drawing data including RGB image data, correcting the color tone of the RGB image data, and outputting the corrected image data to an image output device, wherein the type of the image generating device that generated the RGB image data is set to the drawing data. , And according to the type of the read image generating apparatus, R
An image processing method characterized by switching whether or not to correct the color tone of GB image data. 19. The image processing method according to claim 18, wherein when the type of the image generating device is an image display device, the tone correction processing of the RGB image data is not performed, and the type of the image generating device is an image input device or an unknown type. And performing a color tone correction process on the RGB image data. 20. The image processing method according to claim 19, wherein different color tone correction processes are performed when the type of the image generation device is an image input device and when the type is unknown. 21. A computer which reads a type of an image generating device that has generated RGB image data from the drawing data and switches whether or not to correct the color tone of the RGB image data according to the type of the read image generating device. A computer-readable recording medium recording a program to be executed by a computer.