JP2001016607A - Digital photographing device and digital photographing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly correct a color tone of an image over the entire image. SOLUTION: A digital camera is used to acquire original image data (step ST11) and chromaticity of illumination light is obtained on the basis of an output from a multi-band sensor (step ST12). Conversion on the basis of chromatic adaptation is applied to each pixel of the original image depending on the chromaticity of the light and that of a reference light to correct the color tone (steps ST15, ST16). Thus, proper correction is applied to the entire image and the image when a photographing object is illuminated is obtained as a corrected image. Furthermore, using, e.g. a daylight tone light for the reference light can realize proper color reproduction of the entire image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for correcting a color tone of an image obtained by a digital camera, a scanner, or the like.

[0002]

2. Description of the Related Art Conventionally, image processing for correcting the color tone of an image obtained as digital data by an image input device such as a digital camera or a scanner according to human visual characteristics has been performed. A typical example of such a correction is a correction based on white balance that makes a white object look white (that is, equalizes the average value of each of the RGB values).

In color correction based on white balance,
An output value from a dedicated sensor (a so-called white balance sensor) is used, or a TTL (through the lens) method for specifying a light source from an image obtained by a CCD is used.

[0004]

However, in the system using the white balance sensor, there is a problem that the accuracy of correction is poor when using a light source other than a black system light source (for example, a fluorescent light). The problem is that the effects cannot be completely eliminated. One of the causes of such a problem is that the same correction is uniformly applied to all pixels of an image, so that a white object is corrected to be white, but other color portions are not appropriately corrected. Can be

The present invention has been made in view of the above problems, and has as its object to appropriately correct the color tone of an image obtained by a digital camera or the like for the entire image.

[0006]

According to a first aspect of the present invention, there is provided a digital photographing apparatus, which corresponds to photographing means for photographing an object to be photographed to obtain an image as digital data, and illumination light at the time of photographing. Chromaticity obtaining means for obtaining the chromaticity of light as a first chromaticity; storage means for storing the chromaticity of a predetermined illumination light as a second chromaticity; Correction means for performing color conversion of the image by performing conversion based on chromatic adaptation using the first and second chromaticities.

According to a second aspect of the present invention, in the digital photographing apparatus according to the first aspect, the correction means stores a table for converting color information of each pixel based on chromatic adaptation. There is a means for creating from chromaticity of 2.

According to a third aspect of the present invention, in the digital photographing apparatus according to the first or second aspect, the chromaticity obtaining means includes:
A means for acquiring light intensities in a plurality of wavelength bands;

According to a fourth aspect of the present invention, in the digital photographing device according to the first or second aspect, the photographing means acquires a plurality of preliminary images photographed through each of a plurality of filters as the image. Then, the chromaticity obtaining means obtains the first chromaticity from the plurality of preliminary images.

According to a fifth aspect of the present invention, there is provided a digital photographing method, comprising: a photographing step of acquiring an image as digital data by photographing a photographing object; and a chromaticity of light corresponding to illumination light at the time of photographing. A chromaticity obtaining step of obtaining the chromaticity as one chromaticity, and chromatic adaptation using the first chromaticity and the second chromaticity which is the chromaticity of the predetermined illumination light for the color information of each pixel of the image. A correction process for performing color correction on the image by performing a conversion based on the image.

According to a sixth aspect of the present invention, in the digital photographing method according to the fifth aspect, in the correcting step, the tables for converting the color information of each pixel based on chromatic adaptation are stored in the first and second tables. And a step of creating from the chromaticities of 2.

According to a seventh aspect of the present invention, there is provided the digital photographing method according to the fifth or sixth aspect, wherein the chromaticity obtaining step comprises:
A step of acquiring light intensities of a plurality of wavelength bands with respect to the light from the imaging target.

According to an eighth aspect of the present invention, in the digital photographing method according to the fifth or sixth aspect, in the photographing step, a plurality of preliminary images are taken as the images by photographing through each of a plurality of filters. Acquired in the chromaticity acquiring step, the first image is obtained from the plurality of preliminary images.
Is required.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS <1. First Embodiment> FIG.
Is a digital camera 1 according to the first embodiment of the present invention.
It is a perspective view which shows the whole of FIG. The digital camera 1 includes a lens unit 11 for photographing, and a lens unit 1
And a main unit 12 that processes the image acquired as digital data in 1.

The lens unit 11 has a lens system 111 having a plurality of lenses, and a CCD 112 for acquiring an image of an object to be photographed via the lens system 111. The image signal output from the CCD 112 is transmitted to the main unit 12.
Sent to. In addition, the lens unit 11 includes a viewfinder 113 for the operator to capture the shooting target, and
Multiband sensor 11 used for image processing described later
4 are provided.

Note that other sensors such as a distance measuring sensor are also arranged in the window where the multiband sensor 114 is provided.

The main unit 12 is provided with a flash 121 and a shutter button 122.
By operating, an image is electrically acquired by the CCD 112. At this time, the flash 12
1 emits light.

An image signal from the CCD 112 is transmitted to the main body 12.
The processing described below is performed internally, and the main unit 1
2 is stored in an external memory 123 (a so-called memory card) mounted on the memory card 2. The external memory 123 is the main unit 1
2 When the cover on the lower surface is opened and the take-out button 124 is operated, it is taken out from the main body 12. The data stored in the external memory 123 as a recording medium can be transferred to another device using a separately provided computer or the like. Conversely, the digital camera 1 can read data stored in the external memory 123 by another device.

A liquid crystal display, operation buttons, and the like are provided on the back of the main body 12, and a desired input operation is performed by an operator operating the buttons while looking at the screen.

FIG. 2 shows the configuration of the digital camera 1.
FIG. 2 is a block diagram schematically showing a configuration mainly for executing processing according to the present invention.

In the configuration shown in FIG.
CCD 112, A / D converter 115, shutter button 1
The CPU 22, the ROM 22, and the RAM 23 realize a function of acquiring an image. That is, the lens system 111
Forms an image of the object to be photographed on the CCD 112, and when the shutter button 122 is pressed, the image signal from the CCD 112 is digitally converted by the A / D converter 115.
The digital image signal converted by the A / D conversion unit 115 is stored in the RAM 23 of the main unit 12 in image data (hereinafter referred to as “original image data” in order to distinguish it from corrected image data described later).
That. ) 231 is stored. The control of these processes is performed by the CPU 21 operating according to the program 221 stored in the ROM 22.

The CPU 2 provided in the main body 12
1. ROM 22 and RAM 23 implement the function of processing images. Specifically, in accordance with the program 221 stored in the ROM 22, the CPU 21 performs a color correction process on the acquired image while using the RAM 23 as a work area. At this time, the multi-band sensor 114
Information from is used.

The illumination chromaticity data 232 stored (ie, stored) in the RAM 23 is stored in the multiband sensor 114.
Is generated from the output of The reference light chromaticity data 233 is data used together with the illumination chromaticity data 232 when correcting a color of an image, which will be described later.
T) 234 is generated. The corrected image data 235 is image data generated by correcting the original image data 231 using the LUT 234, and is stored in the external memory 123 as necessary.

The display 24 is a means for displaying an image and displaying information to an operator.
5 is a means for receiving an input operation from the operator.

FIG. 3 mainly shows a CPU 21 and a ROM 22.
FIG. 4 is a block diagram showing a configuration of functions realized by the RAM 23 and other configurations, and FIG. 4 is a flowchart showing a flow of image processing. In the configuration shown in FIG. 3, the illumination chromaticity data generation unit 201, the LUT generation unit 202, and the color correction unit 203 are functions realized by the CPU 21, the ROM 22, the RAM 23, and the like. Hereinafter, the operation of the digital camera 1 will be described with reference to FIGS.

First, the CCD 112 is operated by the photographing operation described above.
Is transmitted from the A / D converter 115 to the RAM 23, and the original image data 2
31 is stored (step ST11).

Next, the output from the multi-band sensor 114 is input to the illumination chromaticity data generator 201. The multiband sensor 114 is a sensor that acquires the intensity of incident light in a plurality of wavelength bands. The intensities of a plurality of wavelength bands obtained by the multi-band sensor 114 are combined by the illumination chromaticity data generation unit 201 to become data indicating the spectral distribution of light corresponding to the illumination light (step ST12).

Generally, in an image of a photographed object illuminated with white light, the average of colors becomes gray.
Is treated as the spectral distribution of the illumination light.

As the multi-band sensor 114, a sensor in which a filter that transmits only light in each wavelength band is provided for each of a plurality of light intensity detectors can be used. For example, a wavelength band in the visible region is divided into a plurality of wavelength bands, and a filter that transmits only light in each wavelength band is provided in each light intensity detector. The plurality of wavelength bands is preferably four or more, but it is possible to estimate the approximate spectral distribution of light incident on the digital camera 1 even with three (for example, three color filters of RGB). In this case, C
The CD 112 can also serve as the multiband sensor 114.

As the small and high-resolution multi-band sensor 114, Nobukazu Kawagoe and two others, "Spectrophotometer CM-100", Minolta Techno Report No.5 1988
(Pp. 97-105), as described in SPD
There is also known a device in which metal film interference filters having different thicknesses are provided on a (silicon photodiode) stepwise. In this multi-band sensor, the thickness of the metal film interference filter is changed for each SPD area, and it is realized that the intensity of light in a predetermined wavelength band is obtained for each SPD area.

When the spectral distribution of the illumination light is determined by the illumination chromaticity data generation unit 201, the chromaticity of the illumination light is further determined and stored in the RAM 23 as illumination chromaticity data 232 (step ST13). Specifically, first, the wavelength is λ, the spectral distribution of the illumination light is E (λ), and the color matching functions corresponding to each color of RGB are r (λ), g (λ), and b (λ), respectively. The stimulus values X, Y, and Z are determined by the equations shown in Equation 1.
Here, k is a coefficient appropriately set.

[0032]

(Equation 1)

Then, using the tristimulus values X, Y, and Z,
The chromaticities xe and ye of the illumination light are obtained by the calculation represented by.

[0034]

(Equation 2)

When the chromaticity of the illumination light is obtained, a reference light is selected (step ST14). The reference light is light assumed to be illumination light in the corrected image,
For example, when daylight-colored light is selected as the reference light, an image of a shooting target illuminated by daytime sunlight is obtained by the following correction processing. The operation button 2 is used to select the reference light by the operator.
5 accepts the digital camera 1 via
The chromaticity of one reference light is determined from the chromaticities of a plurality of types of reference lights stored in the RAM 23 in advance. In addition, RAM
23 stores data relating to a plurality of reference lights as reference light chromaticity data 233. In the following description, data relating to the chromaticity of the selected reference light is simply referred to as reference light chromaticity data 233. I do.

When the reference light is determined, the LUT creation unit 20
2, an LUT 234 for converting a pixel value as color information of the original image is generated using the illumination chromaticity data 232 and the reference light chromaticity data 233, and is stored in the RAM 23 (step ST15).

The LUT 234 is a conversion table referred to in order to quickly convert the pixel value of each pixel in the image based on the chromatic adaptation. This conversion is performed by converting the chromaticity of the illumination light of the original image to xe. , Ye, the chromaticity of the reference light is xr, yr, the original pixel values of RGB are R1, G1, B1, and the converted pixel values of RGB are R2, G2, B2, respectively, and Equation 3 (CIE
(Simplified formula based on the prediction formula of (International Illuminating Engineering Institute)).

[0038]

(Equation 3)

Note that Pr, Pb, and Pg are obtained by Equation (4).

[0040]

(Equation 4)

Further, ξ1, η1, and ζ1 are obtained by Expression 5, and ξ2, η2, and ζ2 are obtained by Expression 6.

[0042]

(Equation 5)

[0043]

(Equation 6)

Here, as the LUT 234, a conversion table is not created for all possible values of RGB pixel values.
34 are created. That is, the pixel values of the original image are RGB
Can take 256 values from 0 to 255 (that is, 700,000 colors) for each of
4 is the converted value to be stored in 2 for each of RGB.
For example, by calculating every other value after conversion instead of obtaining the value 56, the value to be stored in the LUT 234 becomes RG.
B is reduced to 128 for each of them, and is reduced to 64 by calculating the converted value every third.

After the LUT 234 has been created, the LU
Using T234, the color correction unit 203 corrects the image by converting the pixel value of each pixel of the original image. LUT234 is RG
B is created by thinning out the possible values of each of the pixels B. In the actual conversion, the value obtained by performing linear interpolation on the value stored in the LUT 234 according to the pixel value of the pixel of the original image is the converted value. The pixel value is used. When the conversion of the pixel values of all the pixels of the original image is completed, the color information of these pixels is stored in the RAM 23 as corrected image data 235 (step ST16).

Thereafter, the corrected image is displayed on the display 24 based on the corrected image data 235 (step ST17). Further, the corrected image data 235 is stored in the external memory 123 by an input operation of the operator as needed.

The digital camera 1 according to the first embodiment of the present invention has been described above. In this digital camera 1, the chromaticity of the illumination light for the object to be photographed and the chromaticity of the reference light are used. Color correction based on chromatic adaptation is performed for all pixels of the original image. Accordingly, it is possible to perform appropriate color correction that reflects the intention of the operator on the entire image.

In the conventional correction of the color tone based on the white balance, the same conversion is uniformly applied to all pixels, so that the entire image cannot be properly corrected. However, in the digital camera 1 according to the present invention, For example, by using daylight (D65) light as reference light, it matches human vision (that is, considers human color adaptation so that the color remains in the memory of the person who observed the photographing target). Color reproduction can be appropriately performed on the entire image.

When converting the pixel value, the LUT2
Since 34 is created, the amount of processing required for image processing can also be kept low. Further, by preparing a thinned conversion table as the LUT 234, the storage capacity of the RAM 23 can be reduced.

Further, the illumination chromaticity data 232 can be easily obtained by using the output from the multi-band sensor 114.

<2. Second Embodiment> FIG. 5 is a diagram showing a configuration of a digital photographing system 3 according to a second embodiment of the present invention. The digital photographing system 3 includes a monochrome digital camera 31 for acquiring an image to be photographed, a rotary filter 32 having a plurality of filters, and a computer 33 for processing an image obtained by the digital camera 31. The rotary filter 32 has a plurality of filters that transmit only light in a predetermined wavelength band, and limits light incident on the digital camera 31 to a specific wavelength band.

FIG. 6 is a block diagram showing a main configuration of the digital photographing system 3. In the digital camera 1 according to the first embodiment, as shown in FIG. 2, the illumination chromaticity data 232 is obtained using the multiband sensor 114,
Although image processing is performed inside the digital camera 1, in the digital photographing system 3 according to the second embodiment, the illumination chromaticity data 432 is a plurality of images photographed by the digital camera 31. The first embodiment differs from the first embodiment in that the image processing is performed by the computer 33.

As shown in FIG. 6, the digital camera 31 includes a lens system 311, a CCD 312, and an A / D converter 31.
3 and a function of acquiring an image to be captured as digital data.

The computer 33 includes the digital camera 31
CPU 4 has a function of processing an image acquired by
1, ROM 42, RAM 43 and disk drive 4
4 The ROM 42 stores a program 421 for processing an image. The RAM 43 stores preliminary image data 431, illumination chromaticity data 432, reference light chromaticity data 433, and corrected image data 43 after correction.
5 is an area where images are stored or an image processing operation is performed.

The RAM 43 can exchange data with a recording medium such as a fixed disk, a portable magnetic disk, or a magneto-optical disk. Like the first embodiment, the RAM 43 needs corrected image data 435. , And can be stored in a recording medium. In FIGS. 5 and 6, RA is recorded via a disk drive 44 as a recording medium.
The recording medium 9 for transferring data with M43 or the like is illustrated.

Further, an image processing program is stored in the recording medium 9, and this program is read into the RAM 43.
The computer 33 may function as an image processing device by a program in the M42 and a program in the RAM 43.

The computer 33 further has a display 4 for displaying images and displaying information to the operator.
And an input unit 46 such as a keyboard and a mouse for receiving an input from the operator.

Digital camera 31 and computer 3
The configuration according to 3 is similar to the configuration of the digital camera 1 according to the first embodiment as described above, but in this digital photographing system 3, the illumination chromaticity data 432 is obtained using the rotary filter 32. The first point is that
Is different from the embodiment of FIG.

The rotary filter 32 has a configuration in which a disk-shaped rotating body is provided with a plurality of filters that transmit only light in a specific wavelength band, and the digital camera 31 has different wavelengths by rotating the rotating body. Only the light in the band enters while being switched. Each filter corresponds to each wavelength band obtained by dividing the wavelength band of visible light into a plurality.

The computer 33 can recognize which type of filter is located in front of the lens system 311 of the digital camera 31 based on a signal from an encoder provided in the rotary filter 32.

FIG. 7 shows a CPU 41, a ROM 42, and a RAM.
FIG. 7 is a block diagram illustrating a functional configuration and other configurations realized by the illumination chromaticity data generation unit 401 and the color correction unit 403;
This corresponds to a function realized by the work area of the M42 and the RAM 43. Note that, in the digital photographing system 3, unlike the first embodiment, color correction is performed without using an LUT.

FIGS. 8 and 9 show the digital photographing system 3.
6 is a flowchart showing a flow of the operation of FIG. Hereinafter, the operation of the digital photographing system 3 will be described with reference to FIGS.

First, a predetermined filter is used by the digital camera 3.
1 lens system 311 (step ST2).
1) Shooting is performed under the control of the computer 33. As a result, only light in the wavelength band transmitted by the filter is incident on the digital camera 31, and preliminary image data 431 corresponding to one preliminary image is transferred from the A / D converter 313 of the digital camera 31 to the computer 33 and is transmitted to the RAM 43. (Step ST22).

Next, the rotary filter 32 is rotated, and a filter that transmits only light of another wavelength band is formed by the lens system 311.
Is arranged in front of the camera and performs photographing (steps ST21 and S21).
T22). Thereby, the preliminary image data 431 corresponding to another preliminary image is stored in the RAM 43.

Thereafter, by changing the filters and photographing repeatedly (step ST23), the preliminary image data 431 corresponding to each filter is stored in the RAM 43. The preliminary image data 431 includes the rotary filter 3
Information about the filter from No. 2 is given. Shooting a plurality of preliminary images is equivalent to shooting a color image to be shot (ie, an original image).

When the preliminary image data 431 corresponding to a plurality of preliminary images is stored in the RAM 43, the illumination chromaticity data generation unit 401 calculates the spectral distribution of light corresponding to illumination light from the preliminary image data 431. (Step ST
24). That is, the CPU 41 performs an arithmetic process described below according to the program 421 in the ROM 42.

As a method for obtaining the spectral distribution of illumination light from a plurality of preliminary images, any method may be used as long as appropriate data is generated. For example, Shoji Tominaga, "Camera system and algorithm to achieve color constancy",
The technique described in IEICE Technical Report PRU95-11 (1995-05) (pages 77 to 84) may be adopted. In this method, the spectral distribution of the illumination light and the spectral reflectance of the imaging target are obtained as follows.

First, the spectral distribution C (λ) of light incident from a position on a photographing target (hereinafter referred to as “target position”) has a wavelength of λ, a spectral reflectance at the target position of S (λ), and illumination. Assuming that the spectral distribution of light is E (λ),

[0069]

(Equation 7)

Is represented as Here, α and β are scale factors, αS (λ) E (λ) is a diffuse reflection component, and β
E (λ) corresponds to a specular reflection component.

The pixel value of the pixel corresponding to the target position in the image captured by the k-th filter (ie,
The output value of the CCD 312) ρk is defined as Rk (λ), where Sk is the spectral sensitivity of the CCD 312 corresponding to the wavelength band of the filter.

[0072]

(Equation 8)

Is represented as

Here, by using a dimensional linear model expressing the spectral distribution E (λ) of the illumination light and the spectral reflectance S (λ) at the target position as a weighted sum of a plurality of basis functions,
Finally,

[0075]

(Equation 9)

Is transformed. Here, ρ is a vector having a pixel value ρk as an element, and Λ is the spectral reflectance S (λ) at the target position.
Is a matrix representing the response of the sensor to the basis function of the dimensional linear model, σ is the vector of the weighting coefficients of the dimensional linear model of the spectral reflectance S (λ), and H is the dimensional of the spectral distribution E (λ) of the illumination light. A matrix representing the response of the sensor to the basis function of the linear model, and ε is a vector of weighting coefficients of the dimensional linear model of the spectral distribution E (λ).

Then, under the same illumination, σ and ε are obtained from the above equations by using a simplified calculation method while utilizing the rule that the direction of the vector Hε is constant for a plurality of target positions. . Thus, the coefficients of the two dimensional linear models are obtained, and the spectral distribution E (λ) of the illumination light and the spectral reflectance S (λ) at the target position are obtained. Note that only the spectral distribution E (λ) of the illumination light is used in the present invention.

Using the method exemplified above, the illumination chromaticity data generation unit 401 obtains the spectral distribution E (λ) of the illumination light.
In the above description, it is described that the scale factors α and β are appropriately set in advance. However, the calculation may be performed with the scale factor β set to 0 for simple processing.

When the spectral distribution of the illumination light is obtained by the illumination chromaticity data generation unit 401, the chromaticity of the illumination light is subsequently calculated by the calculations shown in Expressions 1 and 2 as in the first embodiment. Is obtained (step ST25). The obtained chromaticity of the illumination light is stored in the RAM 43 as illumination chromaticity data 432.

When the illumination chromaticity data 432 is stored, next, the reference light is selected as in the first embodiment (step ST26). That is, when the input unit 46 of the computer 33 receives an input from the operator, the chromaticity of one reference light is determined from the chromaticities of the plurality of reference lights stored in the RAM 43 in advance. In the following description, the data relating to the chromaticity of the selected reference light is simply referred to as reference light chromaticity data 433.

Next, the color correction unit 403 combines the colors of the plurality of preliminary images to generate an original image represented by RGB pixel values, and preliminarily converts the pixel values of the original image to the preliminary image. Correction is performed (step ST27). The original image was obtained through a filter, and the sensitivity of each of the photographing means constituted by the rotary filter 32 and the digital camera 31 with respect to each of RGB does not completely conform to Equation 1 using the color matching function. Therefore, R
By converting each pixel value of GB using a 3 × 3 matrix, the spectral sensitivity of the photographing unit is made to approximate a color matching function in a pseudo manner.

The 3 × 3 matrix is determined so that the color difference between the color of the image obtained by photographing the color chart and the color of the color chart measured by the colorimeter is minimized.

When the preliminary correction of the original image is completed, a correction based on chromatic adaptation is performed on the original image using the illumination chromaticity data 432 obtained in step ST25 and the selected reference light chromaticity data 433. (Step ST28). That is, the pixel values of each pixel of the original image are converted by performing the operations shown in Equations 3 to 6 on the pixel values of each pixel. The image data corrected by the conversion is stored in the RAM 43 as corrected image data 435.

Thereafter, a corrected image is displayed on the display 45 based on the corrected image data 435 (step ST29). In addition, the corrected image data 435 is stored in the recording medium 9 in accordance with an operator's instruction input from the input unit 46 as necessary.

Although the digital photographing system 3 according to the second embodiment of the present invention has been described above, the digital photographing system 3 uses the chromaticity of the illumination light and the chromaticity of the reference light for the photographing target. Since color conversion based on chromatic adaptation is performed for all pixels of the original image, the color tone of the entire image can be appropriately corrected, as in the first embodiment. Thus, for example, by using daylight (D65) light as reference light, color reproduction suitable for human vision (that is, considering color adaptation) can be performed on the entire image.

In this embodiment, since the calculation is performed without creating a thinned-out LUT, the processing amount is increased, but more appropriate correction is realized.

<3. Modifications> While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-discussed preferred embodiments, but allows various modifications.

For example, in the first embodiment, the creation of a thinned-out LUT is used.
In this embodiment, the original image is preliminarily corrected, but these processes need only be performed as needed. Alternatively, an LUT that has not been thinned out may be prepared as an LUT.

In the second embodiment, the rotary filter 32 is arranged in front of the digital camera 31. However, a mechanism for switching a plurality of filters may be provided inside the digital camera 31. Further, a digital camera 31 having a plurality of (preferably four or more) input bands may be used without providing a filter switching mechanism, so that an image may be obtained for each of a plurality of wavelength bands. .

The digital camera 31 and the rotary filter 32 do not need to be connected to the computer 33 via a transmission line, and the preliminary image data 431 and the like are taken into the computer 33 via a recording medium. Is also good.

Further, the present invention is not limited to the case where an image is obtained using a digital camera, but can be used for an image obtained with another image input device such as a scanner.

[0092]

According to the first to eighth aspects of the present invention, conversion based on chromatic adaptation using the first and second chromaticities is performed on the color information of each pixel of the image. Appropriate color correction can be performed.

According to the second and sixth aspects of the present invention, the amount of calculation can be reduced by using a table.

Further, according to the third and seventh aspects of the present invention, the first chromaticity can be easily obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an entire digital camera according to the present invention.

FIG. 2 is a block diagram showing a configuration for executing processing according to the present invention in the digital camera shown in FIG. 1;

FIG. 3 is a block diagram showing the configuration shown in FIG. 2 divided into functions.

FIG. 4 is a flowchart showing a flow of an operation when correcting a color tone of an image in the digital camera shown in FIG. 1;

FIG. 5 is a diagram showing a configuration of a digital photographing system according to the present invention.

6 is a block diagram showing a configuration for executing processing according to the present invention in the digital photographing system shown in FIG. 5;

7 is a block diagram showing the configuration shown in FIG. 6 divided into functions.

FIG. 8 is a flowchart showing a flow of an operation when correcting a color tone of an image in the digital photographing system shown in FIG. 5;

FIG. 9 is a flowchart showing a flow of an operation when correcting a color tone of an image in the digital photographing system shown in FIG. 5;

[Explanation of symbols]

Reference Signs List 1 digital camera 3 digital photographing system 11 lens unit 21, 41 CPU 22, ROM 23, 43 RAM 31 digital camera 32 rotary filter 33 computer 114 multi-band sensor 201, 401 illumination chromaticity data generator 202 LUT generator 203, 403 Color correction unit 231 Original image data 232, 432 Illumination chromaticity data 233, 433 Reference light chromaticity data 234 LUT 431 Preliminary image data ST11 to ST13, ST15, ST16, ST21 to ST21
ST25, ST28 step

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/46 Z 5C079 F term (Reference) 5B047 AB04 BA03 BB01 BC05 BC07 DB01 DC20 5B057 AA20 BA02 BA29 CA01 CB01 CE17 CH07 5C065 AA03 BB01 CC08 CC09 DD02 DD17 EE06 EE12 FF02 FF05 GG21 GG22 GG23 GG24 GG30 GG31 GG32. 5C079 HB01 JA12 JA16 JA23 LA23 LB01 MA04 NA03 PA00

Claims (8)

[Claims] 1. A digital photographing apparatus, comprising: photographing means for acquiring an image as digital data by photographing a photographing target; and a chromaticity of light corresponding to illumination light at the time of photographing as a first chromaticity. Chromaticity acquiring means for acquiring, chromaticity of a predetermined illumination light as a second chromaticity, and storage means for storing the chromaticity of predetermined illumination light as the second chromaticity;
By performing conversion based on chromatic adaptation using the chromaticity of
A digital photographing apparatus comprising: a correction unit configured to perform color correction of the image. 2. The digital photographing apparatus according to claim 1, wherein the correction means converts a table for converting color information of each pixel based on chromatic adaptation from the first and second chromaticities. A digital photographing apparatus, comprising: a creating unit. 3. The digital photographing apparatus according to claim 1, wherein said chromaticity acquiring means has means for acquiring light intensities in a plurality of wavelength bands. 4. The digital photographing apparatus according to claim 1, wherein the photographing unit acquires a plurality of preliminary images photographed through each of a plurality of filters as the image, and Acquiring means for acquiring the first image from the plurality of preliminary images;
A digital photographing apparatus for determining the chromaticity of a digital image. 5. A digital photographing method, comprising: a photographing step of acquiring an image as digital data by photographing a photographing target; and a chromaticity of light corresponding to illumination light at the time of photographing as a first chromaticity. A chromaticity obtaining step of obtaining; and performing conversion based on chromatic adaptation using the first chromaticity and a second chromaticity that is the chromaticity of predetermined illumination light on the color information of each pixel of the image. And a correction step of performing color correction of the image. 6. The digital photographing method according to claim 5, wherein the correcting step comprises: converting a table for converting color information of each pixel based on chromatic adaptation from the first and second chromaticities. Creating a digital photographing method. 7. The digital imaging method according to claim 5, wherein the chromaticity acquiring step includes a step of acquiring light intensities of a plurality of wavelength bands with respect to light from the imaging target. Characteristic digital photography method. 8. The digital photographing method according to claim 5, wherein in the photographing step, a plurality of preliminary images are acquired as the images by photographing through each of a plurality of filters, and A digital photographing method, wherein in the degree obtaining step, the first chromaticity is obtained from the plurality of preliminary images.