JP2001103508A - Digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decide a white balance adjustment gain of a digital camera by analyzing photographed scene. SOLUTION: The digital camera is provided with a photographing purpose image pickup device 73 that picks up an image of an object passing through a photographing lens 90 to provide an output of image data, an analysis purpose image pickup device 86 that is placed at a position conjugate to the photographing purpose image pickup device 73 with respect to the photographing lens 90 and receives the object image to provide an output of scene analysis image data, and a scene detection processing circuit 35 (Figure 2) that decides a white balance adjustment gain on the basis of the scene analysis image data outputted from the analysis purpose image pickup device 86. The white balance adjustment is applied to image data outputted from the photographing purpose image pickup device 73 on the basis of the white balance adjustment gain decided by the scene detection processing circuit 35 (Figure 2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital camera which images a subject and records the image as electronic image data.

[0002]

2. Description of the Related Art An image pickup device such as a CCD for picking up an image of a subject passing through a photographing lens and outputting image data, and adjusting an amplification gain for image data output from the image pickup device to adjust white balance and γ. 2. Description of the Related Art There is known a digital camera including an image processing circuit for performing image processing such as the above. The image processing circuit calculates parameters such as R gain and B gain for white balance adjustment or a gradation curve for γ correction based on image data output from the imaging device by a predetermined algorithm. Is performed.

[0003]

In the above-described conventional digital camera, a white balance adjustment coefficient is calculated so that color information such as a captured main subject and a background is averaged to obtain an achromatic color, and the calculated adjustment is performed. White balance adjustment is performed on the image data using the coefficients. When photographing a person with such a camera, if the proportion of the skin color portion such as the face in the object scene is small, the white balance adjustment value is calculated mainly from the color information other than the skin color. Incorrect adjustment is likely to occur in a flesh-colored part, and color fading and a color cast image may occur.

An object of the present invention is to provide a digital camera which analyzes a photographic scene, performs white balance adjustment, and can sufficiently suppress color fading and color cast.

[0005]

FIG. 1 shows an embodiment of the present invention.
The present invention will be described with reference to FIG. (1) The digital camera according to the first aspect of the present invention captures an image of a subject passing through the imaging lens 90 and outputs image data. And an analysis imaging device 86 that receives a subject image and outputs scene analysis image data, and at least one of data of a large area of the scene analysis image and data of a small area of the scene analysis image Calculating means 35 for calculating a gain by using
The object described above is achieved by including C and a gain adjustment unit 103 that performs gain adjustment by multiplying the image data output from the imaging device 73 by the gain calculated by the gain calculation unit 35C. (2) In the digital camera according to the first aspect, in the digital camera according to the first aspect, the gain calculating unit 35C selects and selects one of a large area and a small area of the scene analysis image according to the subject. It is characterized in that the gain is calculated using the data of the area. (3) The digital camera according to the third aspect of the invention is a photographic imaging device 73 that captures a subject image passing through the photographic lens 90 and outputs image data, and a conjugate of the photographic lens 90 and the photographic imaging device 73. The image pickup device 86 for analysis, which is provided at an appropriate position and receives a subject image and outputs image data for scene analysis, detection means 35C for detecting at least two colors from data of the image for scene analysis, and detection means 35C A gain calculating unit 35C for calculating a gain using at least one detected color, and a gain for performing a gain adjustment by multiplying the image data output from the imaging device 73 by the gain calculated by the gain calculating unit 35C. Adjusting means 1
03, the above-described object is achieved. (4) According to a fourth aspect of the present invention, in the digital camera according to the third aspect, the detecting means 35C detects at least a flesh color, and the gain calculating means 35C calculates a gain using the flesh color. (5) According to a fifth aspect of the present invention, in the digital camera according to the third aspect, the gain calculating means (35C) comprises a detecting means (35).
One of the two colors detected in C is selected according to the subject, and the gain is calculated using the selected color. (6) The digital camera according to claim 6 captures an image of a subject passing through the photographic lens 90 and outputs image data, and the photographic lens 90 is conjugated to the photographic imaging device 73. And an image pickup device 86 for receiving scene images and outputting image data for scene analysis, and converting data of the image for scene analysis into a first coordinate system and a second coordinate system related to color. Conversion means 3
5C and gain calculating means 35C for calculating a gain using at least one coordinate system converted by the converting means 35C.
The above-mentioned object is achieved by providing a gain adjustment unit 103 that performs gain adjustment by multiplying the image data output from the imaging device 73 by the gain calculated by the gain calculation unit 35C. (7) In the digital camera according to the sixth aspect of the present invention, in the digital camera according to the sixth aspect, the gain calculating unit 35C selects one of the first and second coordinate systems according to the subject, and selects the selected coordinate system. Is used to calculate the gain. (8) The digital camera according to the eighth aspect of the present invention is a photographic imaging device 73 that captures a subject image passing through the photographic lens 90 and outputs image data, and a conjugate of the photographic lens 90 and the photographic imaging device 73. And an image pickup device 86 for receiving a subject image and outputting image data for scene analysis, and a data of a predetermined area of the image for scene analysis in a first coordinate system and a second coordinate system for color. Conversion means 35C for converting to a coordinate system, and one of the first and second coordinate systems is selected according to the size of the area used by the conversion means 35C, and the gain is calculated using the selected coordinate system. Gain calculating means 35C, and a gain adjusting means 103 for performing a gain adjustment by multiplying the image data output from the photographing imaging device 73 by the gain calculated by the gain calculating means 35C. And it allows to achieve the above object. (9) According to a ninth aspect of the present invention, in the digital camera according to the eighth aspect, the conversion means 35C changes the size of the area of the scene analysis image to be used according to the subject.

[0006] In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments are used to make the present invention easier to understand. However, the present invention is not limited to this.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a single-lens reflex digital still camera according to this embodiment includes a camera body 70 and a finder device 8 attached to and detached from the camera body 70.
0, a lens 91 and an aperture 92, and a camera body 70
And an exchangeable zoom lens 90 which is attached to and detached from the camera. The subject light enters the camera body 70 through the interchangeable zoom lens 90, before being released, is guided to the finder device 80 by the quick return mirror 71 located at the position shown by the dotted line to form an image on the finder mat 81, and the focus detection device. 36
Image. The subject light that forms an image on the viewfinder mat 81 is further guided to an eyepiece 83 by a pentaprism 82. In addition, the subject light is supplied to the prism 84 before the release.
Then, the light enters the scene analysis imaging device 86 through the imaging lens 85 to form a subject image. After the release, the quick return mirror 71 rotates to the position shown by the solid line, and the subject light forms an image on the image pickup device 73 via the shutter 72. The imaging device 86 for scene analysis is disposed at a position conjugate with the imaging device 73 for imaging with respect to the imaging lens 91.

FIG. 2 is a block diagram showing a circuit of a digital camera according to an embodiment of the present invention. The CPU 21 receives a half-press signal and a full-press signal from a half-press switch 22 and a full-press switch 23 linked to the release button, respectively. When the half-press switch 22 is operated and a half-press signal is input, the focus detection device 36 detects the focus adjustment state of the interchangeable zoom lens 90 according to a command from the CPU 21, and captures the subject light incident on the interchangeable zoom lens 90. Lens driving device 37 so as to form an image on the imaging device 73
Drives the lens 91 to the in-focus position. Lens information such as the aperture value of the interchangeable zoom lens 90 is input to the CPU 21 via the lens information input unit 38. The CPU 21 drives and controls the CCD 26 of the imaging device 73 for photographing via the timing generator 24 and the driver 25. And
Analog processing circuit 2 by timing generator 24
7 and the operation timing of the A / D conversion circuit 28 are controlled.

When the full-press switch 23 is turned on after the half-press switch 22 is turned on, the quick return mirror 71 rotates upward, and subject light from the interchangeable zoom lens 90 is reflected on the light receiving surface of the CCD 26. Image and CCD
26 stores signal charges corresponding to the brightness of the subject image. The signal charges stored in the CCD 26 are swept out by the driver 25 and input to an analog signal processing circuit 27 including an AGC circuit and a CDS circuit. After analog processing such as gain control and noise removal is performed on the analog image signal by the analog signal processing circuit 27, the A / D
The signal is converted into a digital signal by the conversion circuit 28. The digitally converted signal is guided to, for example, an image processing circuit 29 configured as an ASIC, where image preprocessing such as white balance adjustment, contour compensation, and gamma correction, which will be described later, is performed.

The image data subjected to the image pre-processing is further subjected to a format process (image post-process) for JPEG compression, and the image data after the format process is temporarily stored in the buffer memory 30. You.

The image data stored in the buffer memory 30 is processed by the display image creation circuit 31 into image data for display, and displayed on an external monitor 32 such as an LCD as a photographing result. The image data stored in the buffer memory 30 is subjected to data compression at a predetermined ratio by the compression circuit 33 according to the JPEG method, and is recorded on a recording medium (memory card) 34 such as a flash memory.

FIG. 3 is a block diagram showing details of the image processing circuit 29 in the digital camera operating as described above. FIG. 3 shows a line processing circuit 100 that performs signal processing on image data from the CCD 26 line by line.
The image pre-processing described above is performed. This line processing circuit 100
Performs various kinds of signal processing described later on the 12-bit R, G, and B signals output from the A / D conversion circuit 28. The digital clamp circuit 101, the gain setting circuit 102, and the gain adjustment circuit The circuit includes a circuit 103, a black level circuit 104, and a gamma correction circuit 105.

The 12-bit R, G, and B signals output from the A / D conversion circuit 28 correspond to the output of the CCD 26 by one.
Defective pixels (dot-sequential for each line, whose address is specified in advance and set in a register)
Digital clamp circuit 10 after correcting data from
1 is input. The digital clamp circuit 101
A weighted average of a plurality of pixel data to be used as optical black is subtracted from each pixel data of the line in a dot-sequential manner for each line with respect to the output of D26.

A gain setting circuit 102 sets an adjustment gain for pixel data of each of R, G, and B colors. The adjustment gain is set such that a gain is given to each pixel data of each color output from the CCD 26, and the output level of each color is set to a predetermined level by the given gain.
Even when the output level of the pixel data output from the CCD 26 differs due to the variation of the CCD 26, the image data level input to the gain adjustment circuit 103 is set to a predetermined value regardless of the instrumental difference of the CCD 26 by setting the adjustment gain. Level. Gain adjustment circuit 10
Reference numeral 3 denotes a white balance adjustment gain of R gain and B gain which is calculated by a scene detection processing circuit 35 described later with respect to the input pixel data of each of R and B, and is stored in a memory in the CPU 21. , B signal to perform white balance adjustment.

The black level circuit 104 stores predetermined values stored in the registers of the CPU 21 in R, G,
Add to the B signal. The γ correction circuit 105 includes a CCD
The gamma correction is performed on the 26 outputs using a gradation look-up table in a dot-sequential manner for each line.

-White Balance Detection- The white balance detection processing performed by the scene detection processing circuit 35 of FIG. 2 will be described in detail. The scene detection processing circuit 35 includes an imaging device 86 for scene analysis, an A / D conversion circuit 35B that converts an analog signal from the imaging device 86 for scene analysis into a digital signal, and white balance adjustment based on the converted digital signal. CP that generates coefficients
U35C. The CPU 35C analyzes the scene photographed by the digital data photographed by the scene analyzing photographing device 86, detects a white balance, and determines a white balance adjusting gain. Here, the scene analysis means, for example, an analysis relating to a distribution state of RGB signals of a shooting scene.

The imaging device 86 for scene analysis has, for example, 480 divided into 24 columns × 20 columns as shown in FIG.
It is a single two-dimensional CCD having a number of pixels. As shown in FIG. 5, on the surface of the imaging device 86, R divided into 480 blocks of 24 columns × 20 rows corresponding to 480 pixels is provided.
A GB color filter 861 is provided. As shown in FIG. 5, the 480 block RGB filters are grouped into 16 middle area blocks M11, M12,..., M43, M44 so as to have filter elements each having 6 columns × 5 rows, as shown in FIG. Used for scene analysis. Also,
As shown in FIG. 6, the 480 block RGB filter is
40 small area blocks S11, S12,..., S57, so that each has filter elements of 3 columns × 4 rows.
It is grouped in S58 and used for the second scene analysis.

In the first scene analysis, detection of a color having no hue, that is, a so-called achromatic color, for each of the 16 blocks divided as shown in FIG. Done. When the object field is divided into about 16 middle area blocks, there is a strong possibility that a plurality of colors of the subject exist in one block. Therefore, the first scene analysis is based on the RGs existing in each block.
By averaging the B color data, using the fact that the average value is achromatic when a plurality of colors exist, the R, G,
The achromatic color is detected by averaging the B color data. In each of the 16 divided blocks Mmn, there are ten pieces of data for each color of R, G, and B. Therefore, the color data of each block Mmn is calculated using the following equations (1) to (3). The average values R _M (m, n), G _M (m, n) and B _M (m, n) are calculated.

(Equation 1) Here, R _M (m, n) is 10% belonging to the middle area block Mmn.
The average value of the R data, G _M (m, n) is the middle area block Mm
The average value of 10 G data belonging to n, B _M (m, n) is the average value of 10 B data belonging to the middle area block Mmn.

Using the average values of the R, G, and B color data calculated for each of the 16 blocks in total, the RGB primary colors are measured in accordance with JISZ8725 "Method of measuring light source distribution temperature and color temperature / correlated color temperature". Convert data to TC-Duv coordinate data. When the color temperature (TC) of the 16 data after conversion is plotted on the TC-Duv coordinate, the value of the Duv axis is, for example, ±
Data within 10 is determined to be achromatic, and data exceeding ± 10 is determined not to be achromatic. As a result of the first scene analysis, if there is data determined to be an achromatic color among the color temperatures of the 16 data, the color temperature of this data is set to the color temperature (TC )-Determine the white balance adjustment R gain for the R data and the white balance adjustment B gain for the B data by applying the relationship of the white balance adjustment gain.

The values of the R gain and the B gain determined in FIG. 7 are the Duv values of the data plotted on the TC-Duv coordinates.
This is a value that is previously determined by actual measurement so that the value of the axis is set to 0, that is, data determined to be achromatic is made closer to achromatic, and is expressed as a function of the color temperature (TC). The values of the R gain and the B gain are stored in a storage area of the CPU 35C as a look-up table, and are read out according to the color temperature.

If there are a plurality of data determined to be achromatic among the data of the 16 blocks, the average value of the color temperatures of all the data determined to be achromatic is calculated, and the calculated color temperature is calculated. The average value of the temperature is applied to the relationship between the color temperature (TC) and the gain for white balance adjustment in FIG. 7 to determine the R gain and the B gain. If there is no data determined to be achromatic among the data of the 16 blocks, the white balance adjustment coefficient is not set by the first scene analysis.

In the second scene analysis, a predetermined color, for example, a flesh color is detected for each of the 40 blocks divided as shown in FIG. 6 in the image data output from the image pickup device 86. When the object scene is divided into about 40 small area blocks, there is a strong possibility that the color of the subject existing in one block is one color. Therefore, the second
Scene analysis detects a specific color present in each block. In particular, in this embodiment, the color of a human face, that is, the skin color is detected. Each divided block Sij has:
Since there are four sets of data for each of the colors R, G, and B, each block Si is calculated using the following equations (4) to (6).
The average values R _S (i, j), G _S (i, j) and B _S (i, j) of each color data are calculated for each j.

(Equation 2) Here, R _S (i, j) is the average value of four R data belonging to the small area block Sij, and G _S (i, j) is the small area block Sij
, B _S (i, j) is the average of the four B data belonging to the small area block Sij.

Using the average value of the R, G, and B color data calculated for each of the 40 blocks in total, the ratio between the R data and the G data and the ratio between the B data and the G data are calculated. It is converted into the data of the R / GB / G coordinates as shown. R /
G is calculated by the above equation (4) ÷ the above equation (5), and B / G is calculated by the above equation (6).
算出 Calculated by equation (5). FIG. 8 is a diagram showing a color temperature curve represented by R / GB / G coordinates. In FIG. 8, the color temperature is lower in the lower left portion where the color temperature is lower than 4500K, higher in the upper portion, and 6500K in the uppermost portion.
It is shown that it exceeds. An area 81 surrounded by a dashed line in FIG. 8 is a skin color area detected by the second scene analysis. The color temperature curve of FIG. 8 is stored in the storage area of the CPU 35C as a look-up table, and the R / G
And a color temperature value corresponding to B / G.

The ratio of the average values of the R, G, and B color data calculated for each of the 40 blocks as described above: 40 data are converted into R / GB / G coordinates based on R / G and B / G. When plotted above, the data inside the area 81 is determined to be skin color, and the data outside the area 81 is determined not to be skin color. As a result of the second scene analysis, if there is data determined to be a flesh color from the forty data, a set determination is made as to whether a flesh color is also detected around the area where the flesh color is detected. For example, in FIG.
When the skin color is detected in the region S14 to the region S14 to
S16, area S24, area S26, and area S34 to
Skin color determination is performed in a total of eight areas in S36. Area S2
If a skin color is detected in, for example, three or more of the eight regions around 5, the data in the region S25 is stored as the skin color data. On the other hand, if there are two or less skin color detected areas in the eight surrounding areas, the data in the area S25 is regarded as isolated data and is not stored as skin color data.

When there are a plurality of regions such as S25 in which the skin color data is stored, as described above, the regions Sij
The average value of the color temperature obtained from the color temperature curve of FIG. The calculated color temperature average value is applied to the relationship of color temperature (TC) -white balance adjustment gain in FIG. 7 to obtain a white balance adjustment R gain for R data and a white balance adjustment B gain for B data. decide. If there is only one area such as S25 in which the skin color data is stored, the color temperature obtained in that area is applied to FIG. 7 as it is to determine the R gain and the B gain for white balance adjustment. If there is no area where the skin color data is stored in the 40 blocks, the white balance adjustment coefficient is not set by the second scene analysis.

If the white balance adjustment coefficient is not determined in the first scene analysis and the second scene analysis described above, the color temperature value 5500K stored in the memory in the CPU 35C is read as a default value. By applying this 5500K to FIG. 7, the white balance adjustment coefficient R gain and B
The gain is determined.

The gain adjustment value R determined as described above
Gain and B gain are C as white balance adjustment values.
It is temporarily stored in the register of the PU 21. In the gain adjustment circuit 103 described above, when white balance adjustment is performed on the R and B pixel data input to the gain adjustment circuit 103, the R gain and the B gain stored in the CPU 21 are read out. The R and B signals are multiplied respectively.

The above-described white balance detection processing is shown in FIG.
This will be described with reference to the flowchart of FIG. The white balance detection processing is repeatedly performed at predetermined intervals while the power of the digital still camera is turned on. Step S
At 11, the signal charges are accumulated by the imaging device 86 for scene analysis, and the accumulated charges are swept out and converted into digital data by the A / D conversion circuit 35B.
C is taken in. In step S12, the CPU 3
The data captured in 5C is divided into 16 middle area blocks, and R, G,
The average value of the data of each color B is calculated. In step S13, the 16 sets of RGB data are converted into TC-Duv coordinate data, and in step S14, achromatic data is detected from the data after the coordinate conversion.

In step S15, it is determined whether or not there is detected achromatic data. If it is determined that there are two or more achromatic data (Y (two or more) in step S15), step S16 is performed. Then, the average value of the color temperature (TC) of the detected achromatic data is calculated, and the process proceeds to step S17. If it is determined in step S15 that there is one achromatic data (Y (one) in step S15), the process proceeds to step S17 with the color temperature (TC) of the achromatic data. The above steps S12 to S15 are the first scene analysis processing.

On the other hand, if a negative determination is made that there is no achromatic data detected in step S15 (step S15).
In 15N), the second scene analysis after step S19 is performed. In step S19, step S11
The data fetched by the CPU 35C is divided into 40 small area blocks, and the average values of the R, G, and B color data existing for each of the divided blocks are calculated. In step S20, 40 sets of RGB data are R / GB /
The coordinates are converted to G coordinate data, and in step S21, flesh color data is detected from the data after the coordinate conversion.

In step S22, a set determination process is performed in which the skin color data is regarded as skin color data only when a predetermined number or more of skin colors are detected in eight small region blocks around the small region block where the skin color data is detected. As a result of the set determination process, it is determined in step S23 whether or not there is skin color data regarded as skin color data, and when it is determined that there is two or more skin color data (Y (two or more) in step S23). Proceeds to step S24, calculates the average value of the color temperature (TC) calculated from the detected flesh color data, and proceeds to step S1.
Proceed to 7. If it is determined in step S23 that there is one skin color data (Y (one) in step S23),
The process proceeds to step S17 with the color temperature (TC) of the skin color data. If it is determined in step S23 that there is no skin color data (N in step S23), the process proceeds to step S25, in which the color temperature value 5500K stored in the CPU 35C is read as a default value, and the process proceeds to step S17.

In step S17, the R gain and the B gain for white balance adjustment are read from the look-up table stored in the storage area of the CPU 35C based on the color temperature (TC). Read R gain, B
When the gain value is stored in the CPU 21 in step S18, the processing in FIG. 10 ends.

The operation of the digital still camera thus configured will be described. FIG. 11 is a flowchart showing a program started by the half-press switch. When the half-press switch 22 is operated, in step S31, a focus detection operation of the photographing zoom lens 90 and a photometric operation of detecting the brightness of the subject are performed. When the focus detection state is detected by the focus detection device 36, the lens driving device 37 drives the lens 91 to the in-focus position based on the detected focus adjustment state. The luminance of the subject is detected by the CPU 35C using the data output from the imaging device 86 for scene analysis. The luminance data detected by the CPU 35C is
When output to 1, the CPU 21 performs an exposure calculation based on the luminance data and the aperture value of the zoom lens 90 sent from the lens information input unit 38.

In step S32, the R gain and B gain values for white balance adjustment stored in the register of the CPU 21 are read as described above. If it is determined in step S33 that the full-press switch 23 has been operated, the quick return mirror jumps up,
The shooting sequence is started. In step S34, C
Each pixel of the CD 26 accumulates the light receiving signal, and after the accumulation is completed, the accumulated charges of all the pixels are sequentially read. In step S35, the read image data is stored in the analog signal processing circuit 2
After being processed in 7, the data is converted into digital image data by an A / D conversion circuit 28 and input to an image processing circuit 29. Next, proceeding to step S36, the above-described white balance adjustment, γ gradation correction, JPEG formatting, and the like are performed by the image processing circuit 29. When the image processing is completed, the process proceeds to step S37, and the image data after the image processing is temporarily stored in the buffer memory 30. In step S38, image data is read from the buffer memory 30 and J
The data is compressed by the PEG compression circuit 33. Step S3
In step 9, the compressed image data is stored in the memory card 34, and the process ends.

In the above description, the case of photographing under natural light has been described. For example, when photographing under fluorescent light, it is necessary to adjust the gain for white balance adjustment. Generally, the color temperature of the captured RGB data is higher when photographing under a fluorescent light than when photographing under natural light. This color temperature difference is corrected by correcting the values of the R gain and the B gain in FIG. 7 by a predetermined amount. Therefore, two sets of lookup tables storing the values of the R gain and the B gain are prepared for photographing under natural light and for photographing under fluorescent light, and are read out by switching according to the photographing light at the time of photographing. To do.

The features of this embodiment will be summarized. (1) In the first scene analysis of steps S12 to S15, the object scene is divided into 16 medium regions, the average of each color data of RGB is obtained for each of the divided regions, and the data on the TC-Duv coordinates is obtained. To achromatic data. As a result, there is a strong possibility that a plurality of colors of the subject exist in one middle area block.
Averaging the GB color data has the effect of making it easier to detect achromatic colors. Also, if the number of divided areas is large, the amount of calculation at the time of conversion processing to TC-Duv coordinates increases,
With six regions, the load on the CPU can be reduced, and the effect of reducing the processing time can be obtained. (2) The average of the color temperatures of the achromatic data detected in the first scene analysis is calculated, and the R gain and the B gain for white balance adjustment are determined according to the calculated average of the color temperatures. Therefore, the average white balance adjustment is performed for the entire screen, and the color of the subject can be reproduced.

(3) In the second scene analysis of steps S19 to S23, the object scene is divided into 40 small areas, and the average of RGB color data is obtained for each divided area to obtain R / GB / Converted to data on G coordinate to detect flesh color data. Further, a set determination process is performed on the detected skin color data, and when a predetermined number or more of the surrounding data is skin color, the data is regarded as skin color data again. As a result, it is more likely that the subject in one small area block is one color, and this has an effect of making it easier to detect a specific color present in the block. (4) The average of the color temperatures of the data regarded as the skin color data in the second scene analysis is calculated, and the R gain and B for white balance adjustment are calculated according to the calculated average of the color temperatures.
Since the gain is determined, optimal white balance adjustment is performed on the skin color portion of the object scene. Therefore, for example, when a person is photographed against a green background, the skin color of the person can be reproduced regardless of the background color.

(5) Since the scene analysis image pickup device 86 is disposed in the viewfinder device 80, the scene analysis image pickup device 86 is operated before the mirror 71 is mirrored up by operating the full-press switch 23. It becomes possible to image the data for scene analysis, determine the gain for white balance adjustment, and store it in the CPU 21. Therefore, since it is not necessary to determine the white balance adjustment gain in the shooting sequence from step S34 performed by operating the full-press switch 23, the shooting processing time is shorter than when the scene analysis data is shot by the shooting can. Can be shortened. (6) The imaging device 86 for scene analysis is used for both the imaging of the data for scene analysis and the luminance detection of the subject, so that the mounting space can be reduced as compared with the case where the imaging device 86 is not shared. The effect of reducing costs can be obtained.

In the above description, the scene is divided into 16 medium regions in the first scene analysis, and the scene is divided into 40 small regions in the second scene analysis. The number of these divisions may not be as described. In addition, although it has been described that the image is divided into rectangles so as to be equally divided, these may not be equally divided and may not necessarily be divided into rectangles. Furthermore, although the entire area of the area received by the imaging device 86 for scene analysis is divided, only a specific area may be used.

In the above description, 16 sets of RGB data based on the 16 regions divided by the first scene analysis are coordinate-converted into TC-Duv coordinate data, and the data is converted into 40 regions divided by the second scene analysis. Forty sets of RGB data were converted to R / GB / G coordinate data. If the number of divisions is not necessarily 16 or 40, the data of the smaller number of divisions is used to convert the coordinates to data of TC-Duv coordinates, and the data of the larger number of divisions is used to convert the data of R / GB / G coordinates. What is necessary is just to convert coordinates. Also, regardless of the number of divided areas,
The coordinates to be converted may be selected according to the purpose of photographing. For example, when shooting multi-colored subjects such as snapshots, if you select TC-Duv coordinates, you can perform average white balance adjustment for all colors, When shooting
If the R / GB / G coordinates are selected, the optimum white balance adjustment can be performed for a specific color such as skin color.

In the above description, the skin color is detected in the second scene analysis to determine the white balance adjustment gain. However, instead of the skin color, for example, a green color or an achromatic color may be detected. . Further, the color to be detected can be switched according to the photographing mode so that the skin color is detected when a person is photographed and the green color is detected when a landscape is photographed. For example, if green is detected in the distant view mode and flesh color is detected in the portrait mode, optimal white balance adjustment for each detected color is achieved. Will be performed. Furthermore,
A plurality of colors such as flesh color and green may be detected, and the color for which the number of data determined as a group by the group determination processing is maximum may be adopted to determine the white balance adjustment gain.

In the above description, the second scene analysis is performed when no achromatic color is detected as a result of the first scene analysis. However, the first scene analysis and the second scene analysis are performed. One of the scene analysis may be selected and performed, and the white balance adjustment gain may be determined based on the color temperature obtained by the selected scene analysis. Also, by performing both scene analyses, it is also possible to determine the white balance adjustment gain by averaging two color temperatures obtained by the two scene analyses.

In the above description, a single-lens reflex digital still camera has been described. However, the present invention can be applied to a non-single-lens reflex digital camera. In this case, the subject images are separately formed on the imaging device for photographing and the imaging device for scene analysis using a beam splitter, a half mirror, or the like. In the above description, the imaging device for photographing and the imaging device for scene analysis are separately provided. However, the imaging device for photography may also be used as the imaging device for scene analysis. In this case, when the power is turned on, regardless of the operation of the release button, the subject image picked up by the image pickup device is repeatedly displayed as a through image on a display device such as a liquid crystal monitor. The white balance adjustment gain is determined as described above using the captured data. Then, white balance adjustment is performed on the subject image data captured when the release operation is performed by using the white balance adjustment gain.

In the above description, the TC-Duv coordinate system and the R / GB / G coordinate system are used as the coordinate systems related to the colors. However, the coordinate system using the color difference signals RY and BY is used. You can also.

The correspondence between each component in the claims and each component in the embodiment of the present invention will be described.
D26 is an imaging device for photographing, and an imaging device 86 for scene analysis.
Is in the imaging device for analysis, the middle region blocks M11 to M44 are in a large region, the small region blocks S11 to S58 are in a small region, the CPU 35C is in a gain calculating unit, a detecting unit and a converting unit, and the TC-Duv coordinate system is in a first region. R / GB /
The G coordinate system corresponds to the second coordinate system, and the gain adjustment circuit 103 corresponds to gain adjustment means.

[0046]

According to the present invention as described in detail above, the following effects can be obtained. (1) According to the first and second aspects of the present invention, at least one of data of a large area of a scene analysis image and data of a small area of a scene analysis image is used to calculate a gain for gain adjustment with respect to the image data for photographing. I did it. Therefore, when data of a large area is used, there is a high possibility that a plurality of colors of the subject exist in the area, and when a small area is used, there is a high possibility that the color of the subject becomes one color. By performing gain adjustment using this relationship, it is possible to suppress the color drop and the color cast. (2) In the invention of claims 3, 4, and 5, at least two colors are detected from the data of the image for scene analysis, and at least one of the detected colors is used to adjust the gain for gain adjustment for the image for photographing. It was calculated. As a result, for example, when performing portrait photography, if the skin color is detected and the gain for gain adjustment is calculated, the optimal gain for the skin color can be calculated, and the skin color is correctly reproduced. .

(3) According to the sixth and seventh aspects of the present invention, the image data for scene analysis is converted into the first coordinate system and the second coordinate system related to color. It can be represented by coordinates of the color temperature and the degree of separation from the achromatic color, or can be represented by the coordinates of the magnitudes of the R color component and the B color component. Therefore, for example, in the case of portrait photographing, when the gain calculating means calculates the gain for gain adjustment by detecting the skin color from the image data for scene analysis, it uses the coordinates of the magnitudes of the R color component and the B color component. Then, it becomes easier to detect the flesh color. (4) In the invention of claim 8, the first coordinate system and the second coordinate system are selected according to the area of the image data for scene analysis used for coordinate conversion. In the case of a large area, there is a high possibility that there are multiple colors of the subject in the area,
In the case of a small area, there is a high possibility that the color of the subject becomes one color. By performing gain adjustment using this relationship, it is possible to suppress the color drop and the color cast. (5) In the invention of claim 9, in addition to the configuration of claim 8,
The size of the area of the image data for scene analysis used for coordinate transformation is changed according to the subject. Therefore, if it is better to detect the skin color and calculate the gain for gain adjustment, such as in portrait photography, and use a small area, the coordinates of the size of the R color component and the B color component can be selected. And it becomes easier to detect skin color.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an embodiment of a single-lens reflex digital still camera.

FIG. 2 is a block diagram showing an embodiment of a signal processing system of the single-lens reflex digital still camera.

FIG. 3 is a block diagram illustrating a circuit that performs line processing in the signal processing system illustrated in FIG. 2;

FIG. 4 is a diagram illustrating a pixel array of the imaging device for scene analysis.

5 is a diagram showing an arrangement of color filters provided on the image pickup apparatus of FIG. 4 and a middle area division.

FIG. 6 is a diagram illustrating a small area division of the imaging apparatus of FIG. 4;

FIG. 7 is a graph showing a relationship between a color temperature and a gain for white balance adjustment.

FIG. 8 is a diagram of a color temperature curve represented on R / GB / G coordinates.

FIG. 9 is a diagram illustrating a set determination.

FIG. 10 is a flowchart illustrating white balance detection processing.

FIG. 11 is a flowchart showing a program started by a half-press switch.

[Explanation of symbols]

21: CPU, 22: Half-press switch, 23: Full-press switch, 2
6 CCD, 28 A / D conversion circuit,
29 ... Image processing circuit, 33 ... JPEG compression circuit,
35: scene detection processing circuit, 35B: A / D conversion circuit, 35C: CPU, 36: focus detection device, 37: lens drive device, 3
Reference numeral 8: lens information input unit; 73, an imaging device for photographing; 86, an imaging device for scene analysis;
… Interchangeable zoom lens, 91… Shooting lens,
92: aperture, 100: line processing circuit,
102: gain setting circuit, 103: gain adjustment circuit, M11 to M44: medium area divided into 16, S11 to S58: small area divided into 40

Continued on the front page F term (reference) 5C065 AA03 BB02 BB04 BB10 BB12 BB23 CC08 CC09 DD02 DD17 EE06 EE13 FF03 GG15 GG17 GG18 GG23 GG30 GG31 GG32 GG35 5C066 AA01 BA20 CA08 CA17 DD01 DD07 EA08 EA02 EC02 KE03 KE05 KE09 KE17 KE19 KE24 KF05 KM02 KM05

Claims (9)

[Claims] An image pickup device for picking up an image of an object passing through an image pickup lens and outputting image data; and an image pickup device arranged at a position conjugate with the image pickup device for image pickup with respect to the image pickup lens. An imaging device for receiving image data and outputting scene analysis image data; and a gain for calculating a gain using at least one of data of a large area of the scene analysis image and data of a small area of the scene analysis image. A digital camera, comprising: a calculating unit; and a gain adjusting unit configured to apply a gain calculated by the gain calculating unit to image data output from the photographing imaging apparatus to perform a gain adjustment. 2. The digital camera according to claim 1, wherein said gain calculating means selects one of a large area and a small area of said scene analysis image according to a subject, and stores data of the selected area. A digital camera characterized in that the gain is calculated using the digital camera. 3. An imaging device for capturing an image of an object passing through an imaging lens and outputting image data, the imaging device being disposed at a position conjugate to the imaging device with respect to the imaging lens, and An imaging device that receives image data and outputs scene analysis image data; a detection unit that detects at least two colors from the data of the scene analysis image; and a gain using at least one color detected by the detection unit. And a gain adjusting means for performing a gain adjustment by multiplying the image data output from the photographing imaging device by a gain calculated by the gain calculating means. camera. 4. The digital camera according to claim 3, wherein said detecting means detects at least a flesh color, and said gain calculating means calculates a gain using said flesh color. 5. The digital camera according to claim 3, wherein said gain calculating means selects one of the two colors detected by said detecting means in accordance with a subject, and calculates a gain using the selected color. A digital camera characterized by calculating. 6. An imaging device for capturing an image of an object passing through an imaging lens and outputting image data, the imaging device being disposed at a position conjugate with the imaging device for the imaging with respect to the imaging lens, and An image capturing apparatus for receiving image data and outputting scene analysis image data; a conversion unit configured to convert the data of the scene analysis image into a first coordinate system and a second coordinate system related to color; Gain calculating means for calculating a gain using at least one of the converted coordinate systems; and performing gain adjustment by multiplying the image data output from the imaging device for photographing by the gain calculated by the gain calculating means. A digital camera, comprising: a gain adjusting unit. 7. The digital camera according to claim 6, wherein said gain calculating means selects one of said first and second coordinate systems according to a subject, and uses the selected coordinate system to obtain a gain. A digital camera characterized by calculating 8. An image pickup device for picking up an image of an object passing through an image pickup lens and outputting image data; and an image pickup device arranged at a position conjugate to the image pickup device for image pickup with respect to the image pickup lens. An imaging device for receiving image data and outputting image data for scene analysis, and conversion means for converting data of a predetermined area of the image for scene analysis into a first coordinate system and a second coordinate system related to color, Gain calculation means for selecting one of the first and second coordinate systems according to the size of the area used by the conversion means and calculating a gain using the selected coordinate system; And a gain adjustment unit for multiplying the image data output from the imaging device by the gain calculated by the gain calculation unit to adjust the gain. 9. The digital camera according to claim 8, wherein said converting means changes a size of an area of said scene analysis image to be used according to a subject.