JP2002277922A - Automatic exposure control method and unit, and digital camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic exposure control method which stably extracts a high-luminance part and can effectively remove high luminance. SOLUTION: By the automatic exposure control method which divides a photographed image into many small areas and performs high-luminance processing according to an evaluated value found from the integral value of luminance signals of light made incident on the small areas from an optical system to perform exposure control, intermediate areas are set by combining small areas and intermediate areas for luminance difference decision making are set as areas of upper and lower areas of the photographed image among the intermediate areas or intermediate area for luminance difference decision making are set as areas of right and left areas of the photographed image. Further, when the luminance difference of the intermediate area for luminance difference decision making at the opposite position is larger than a luminance threshold and the lighter value of the intermediate area for the luminance difference decision making is less than a light part threshold, the set area of an evaluation intermediate area where center light reading or spot light reading is performed is moved to a lower luminance direction and the exposure evaluated value found in the evaluation intermediate area after the movement is used to perform the exposure control.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic exposure control method, an automatic exposure control device, and a digital camera.
In particular, the present invention is suitably applied to an image input device using an image sensor such as a digital video camera and a digital camera.

[0002]

2. Description of the Related Art Exposure determination methods in a conventional automatic exposure control apparatus include an average metering, a center-weighted metering, a spot metering,
There are methods such as multi-pattern photometry. In any case, a plurality of predetermined evaluation areas are set in the image area including the entire captured image, an exposure evaluation value is obtained from the average luminance information of the area, and the exposure is determined based on the exposure evaluation value. And exposure compensation such as backlight compensation. In determining the evaluation area, the image area is divided into a large number of grid-like areas (hereinafter, referred to as small areas) as shown by a broken line in FIG.
In many cases, an area obtained by combining the divided areas (hereinafter, referred to as a medium area) is set as an evaluation area. The region surrounded by the thick line in FIG. 2 is a combination of evaluation regions generally seen in the center-weighted system. The evaluation value of the evaluation area (hereinafter, referred to as a medium area evaluation value) is obtained by averaging the integrated values of the luminance signals of the small areas included therein. Exposure control when performing center-weighted photometry as shown in FIG.
Generally, weighting is applied to the middle area near the center of the two middle areas. In the case of spot metering, exposure control is performed by a central area that is the same as or smaller than the central middle area shown in FIG. Further, when there is not much difference in luminance, the exposure control is performed by arranging the evaluation area at the center of the image as shown in FIG. Generally, since the evaluation value is obtained by the average luminance, if there is a portion of the captured image as shown in FIG. Will be expensive. Then, since the exposure matches the brighter one, FIG. 14 (b)
As a result, the whole image becomes dark. In particular, in the case of center-weighted exposure as shown in FIG. 2, if a bright portion such as a spotlight exists at the center, the effect is large.

[0003] JP-A-5-122600 and JP-A-7-122600
According to the technique disclosed in Japanese Patent Application Laid-Open No.-298131, when the luminance value of each small area exceeds a predetermined threshold (hereinafter, referred to as a high luminance threshold), the luminance value of the small area is set to a predetermined value (hereinafter, referred to as a high luminance threshold). , High brightness specified value) to solve this problem. For example, a problem of the high luminance processing will be described with reference to FIG. FIG. 6A is a model of a landscape photograph in which a mountain or the like is photographed, and the sky, which is considerably brighter than the lower mountain or the ground, is located almost from the center of the screen to the upper side. . For this reason, when center-weighted photometry or spot photometry is performed, the effect of the high-brightness part of the sky is large, resulting in a dark image as a whole as shown in FIG. Therefore, the influence of the high-brightness portion is eliminated by replacing the high-brightness portion with a predetermined high-brightness specified value (including zero) for a high-brightness portion that is equal to or higher than a predetermined threshold (high-brightness threshold), as shown in FIG. A bright image can be obtained.

[0004]

In such a conventional technique, a high-brightness part is replaced or excluded.
Although the effect of high-luminance parts such as sky and spotlight can be suppressed, high-luminance parts exist only when the exposure during shooting matches the low-luminance part. In the case where a wide high-luminance part and a low-luminance part are mixed, such as the sky, the evaluation area is adjusted to the low-luminance side from the state where the evaluation area matches the high-luminance part. When the area is moved, the high-luminance area cannot be extracted because the captured image is exposed on the high-luminance side. In such a case, a method has been proposed in which, in the case of an image having a luminance difference, the evaluation area is moved to a darker side of the image so that high luminance can be removed so that high luminance extraction can be performed. For example, FIG. 7 shows a general center-weighted evaluation area when the luminance difference is small, FIG. 10 shows a case where the upper side is dark, FIG. 8 shows a case where the lower side is dark, FIG. 11 shows a case where the right side is dark, and FIG. The left side shows the movement of the center-weighted photometry area when it is dark.

However, if thresholds and evaluation values for judgment when moving the evaluation area are not properly determined, hunting occurs in which the display image for monitoring becomes bright or dark, or the judgment is not performed properly. In some cases, the effect may not be sufficiently exhibited. If the high brightness threshold for determining the high brightness portion is fixed,
Depending on the situation, the high-luminance part does not exist, and the high-luminance processing may not be performed. This depends on whether the exposure of the camera changes from the dark side or from the bright side. For example, consider a case in which exposure control is continuously applied to display on an LCD monitor or the like. When the center of the image faces the dark ground as shown in FIG. 6B, the dark part of the ground is exposed. When the camera moves from this state to the angle of view as shown in FIG. 6C, the high-brightness processing at this time is performed while maintaining the high-brightness threshold value for the dark part of the ground and the height of the sky part in FIG. Brightness processing is performed. Conversely, when the center of the image faces the sky as shown in FIG. 6D, the high brightness threshold is high because the exposure matches the high brightness of the sky. FIG.
When the direction of the camera is changed to a state as shown in (e), the high-brightness processing is performed with the high-brightness threshold remaining, so the high-brightness portion of the image disappears, and the high-brightness processing is not performed. 6 (e) results in a dark image as a whole.
Also, when the high luminance threshold for determining the high luminance portion is fixed, there is a method of lowering the high luminance threshold for an image having a luminance difference. If you do not properly set the high brightness threshold each time,
Again, hunting occurs in which the monitoring display image becomes brighter or darker. Although an example of automatic exposure correction has been shown for display on an LCD monitor or the like, the same occurs when continuous exposure control is not performed. For example, in actual shooting, this occurs when the exposure is changed several times for exposure control such as coarse adjustment and fine adjustment.

[0006] Such a problem is solved by changing a high luminance threshold value for judging a high luminance portion in accordance with an image. However, in order to determine the high luminance threshold, it is necessary to grasp the situation of the entire image, and there is a new problem that processing time is required. The present invention solves the above problems by changing a high-brightness threshold value according to an image, a high-brightness portion is stably extracted, and an automatic exposure control method capable of effectively removing high-brightness. It is an object to provide an exposure control device and a digital camera.

[0007]

In order to solve the above-mentioned problems, according to the automatic exposure control method of the present invention, a photographed image is divided into a number of small areas, and the small area is incident from an optical system. Based on the evaluation value obtained from the integrated value of the luminance signal of the light, in an automatic exposure control method for performing exposure control by performing high-luminance processing, a plurality of middle areas are set by combining a plurality of the small areas, From the middle area, the middle area for brightness difference determination is provided in the area of the upper and lower part of the captured image, or the middle area for brightness difference determination is provided in the area of the left and right part of the captured image, and the middle area for brightness difference determination is located at the opposite position. When the brightness difference is equal to or greater than the brightness difference threshold, and the brighter value of the facing brightness difference determination medium area is equal to or less than the bright part threshold, the setting area of the evaluation area in which high brightness processing is performed is shifted in the direction of lower brightness. Move and request in the evaluation area after the move. And performing exposure control using the obtained exposure evaluation value. Further, claim 2 of the present invention
The automatic exposure control method according to the first aspect is characterized in that, in the automatic exposure control method according to claim 1, the bright part threshold value is changed depending on whether or not the evaluation area has been moved. Also,
According to a third aspect of the present invention, there is provided an automatic exposure control method according to the first or second aspect, wherein a middle area for judging brightness is provided in a central portion of the image, and the middle area for performing high brightness processing is set. When moving the area in the direction of lower luminance, the moving amount of the evaluation area is changed according to the evaluation value of the middle area for luminance determination and the middle area for luminance difference determination in the image central part. It is characterized by. In the automatic exposure control method according to a fourth aspect of the present invention, in the automatic exposure control method according to the third aspect, a small area in the middle area for luminance determination at the center of the image is larger than a predetermined threshold. In this case, the evaluation value is calculated by excluding the small area, and when the evaluation value is equal to or less than a certain threshold, the set area of the area being evaluated is moved.

According to a fifth aspect of the present invention, there is provided an automatic exposure control apparatus which divides a photographed image into a plurality of small areas and evaluates the evaluation value obtained from an integral value of a luminance signal of light incident on the small area from an optical system. In the automatic exposure control device that performs exposure control by performing high-luminance processing, based on the exposure evaluation value obtained from the exposure evaluation target middle region among a plurality of middle regions obtained by combining the plurality of small regions, Exposure control means for controlling the middle area, setting means for setting the middle area for brightness difference determination in the upper and lower parts of the captured image, or the middle area for brightness difference determination in the left and right areas of the captured image from the middle area It is determined that the brightness difference of the middle region for brightness difference determination at the facing position is equal to or greater than a predetermined brightness difference, and that the brighter value of the facing middle region for brightness difference determination is equal to or less than a predetermined threshold value. Determination means Moving means for moving the set area of the area under evaluation for performing high-luminance processing in the direction of lower luminance when the judgment means judges true, and moving the set area when the judgment means judges true. The exposure control is performed using the exposure control value obtained by the exposure control means for the area under evaluation after the movement by the means. Also,
In the automatic exposure control device according to a sixth aspect of the present invention, in the automatic exposure control device according to the fifth aspect, the determination unit changes the bright portion threshold depending on whether the evaluation area has been moved. It is characterized by. Further, in the automatic exposure control device according to claim 7 of the present invention, in the automatic exposure control device according to claim 5 or 6, the setting means further includes a middle area for luminance determination in a central portion of the image, The means of transportation is
When the set area of the middle area to be subjected to the high brightness processing is moved in the direction of lower brightness, the movement of the middle area is evaluated based on the evaluation values of the middle area for brightness determination and the middle area for brightness difference determination in the central part. It is characterized in that the amount is changed. The automatic exposure control device according to claim 8 of the present invention provides the automatic exposure control device according to claim 7.
In the automatic exposure control device according to the above, when the evaluation means calculates the evaluation value of the middle area for brightness determination of the central portion of the image, it is determined that there is a small area in the middle area for brightness determination of the central portion of the image When the evaluation value is larger than the threshold value, the evaluation value is calculated by excluding the small area. Is moved.

A digital camera according to a ninth aspect of the present invention is provided with the automatic exposure control device according to any one of the fifth to eighth aspects. An automatic exposure control device according to a tenth aspect of the present invention divides a captured image into a plurality of small areas and calculates an evaluation value obtained from an integral value of a luminance signal of light incident on the small area from an optical system. In an automatic exposure control device that performs exposure control by performing high brightness processing, a histogram creating unit that creates a histogram related to brightness from the evaluation value of the small area, and a frequency of a section of the histogram created by the histogram creating unit is determined. High frequency section extracting means for obtaining a section (hereinafter, referred to as a high frequency section) larger than the obtained frequency threshold, and high luminance determining a high luminance threshold based on the high frequency section extracted by the high frequency section extracting means. Value calculation means, and exposure evaluation value conversion for performing high brightness processing of the brightness integrated value for each of the small areas based on the high brightness threshold value determined by the high brightness value calculation means and converting the result into an exposure evaluation signal. And a stage, and performs exposure control by the exposure evaluation signal. The automatic exposure control device according to claim 11 of the present invention is the automatic exposure control device according to claim 10, wherein the high luminance value calculating means includes a high-frequency section obtained by the high-frequency section extracting means. A maximum-minimum high-frequency section determining means for obtaining a section on the lowest luminance side (hereinafter, referred to as a minimum high-frequency section) and a section on the highest luminance side (hereinafter, referred to as a maximum high-frequency section); High brightness threshold value determining means for determining a high brightness threshold value based on a section difference between the maximum high frequency section and the minimum high frequency section obtained by the frequency section determining means is provided.

According to a twelfth aspect of the present invention, in the automatic exposure control apparatus according to the eleventh aspect, the maximum / minimum high-frequency section determining means determines the minimum high-frequency section in which the minimum high-frequency section is determined. If it is larger than the section, the frequency is sequentially added from the lowest luminance section to the higher luminance side of the histogram, and if the added value is larger than the frequency threshold, the section is set to the minimum high frequency. It is characterized by being reset as a section. According to a thirteenth aspect of the present invention, in the automatic exposure control device according to the eleventh or twelfth aspect, an average value of the histogram created by the histogram creating means (hereinafter, referred to as a frequency average value) is used. Average value calculation means for calculating the maximum brightness frequency determination means, and the high brightness threshold value determination means, when the section difference between the maximum high frequency section and the minimum high frequency section obtained by the maximum minimum minimum high frequency section determination means is small, The frequency average value obtained by the average value calculation means is used as a reference value. If the section difference is large, the minimum high frequency section is used as the reference value, and a value higher than the reference value by a value determined on the high brightness side is used as a high brightness value. It is characterized in that it is determined as a threshold. In the automatic exposure control device according to a fourteenth aspect of the present invention, in the automatic exposure control device according to the tenth aspect, the exposure evaluation value converting means may provide high brightness depending on a shooting condition and / or a distribution state of the histogram. The processing is switched. In the automatic exposure control device according to a fifteenth aspect of the present invention, in the automatic exposure control device according to the fourteenth aspect, the exposure evaluation value converting means is configured such that an exposure condition at the time of shooting is higher than a predetermined exposure, or When the maximum high-frequency section is larger than the maximum section defined by the exposure condition at the time of shooting and the section difference between the maximum high-frequency section and the minimum high-frequency section is larger than the predetermined section difference, The exposure evaluation value is obtained by performing high brightness processing without using the evaluation value of the small area equal to or larger than a threshold value, otherwise, the high brightness processing is performed by replacing the evaluation value of the small area with another predetermined value. And an exposure evaluation value is obtained.

According to a sixteenth aspect of the present invention, in the automatic exposure control apparatus according to the fourteenth aspect, the exposure evaluation value converting means is configured to set an exposure condition at the time of photographing lower than a predetermined exposure. If the maximum high-frequency section is smaller than the maximum section determined by the exposure condition at the time of shooting and the section difference between the maximum high-frequency section and the minimum high-frequency section is larger than the predetermined section difference, An intermediate section between the high-frequency section and the minimum high-frequency section is obtained, and the sum of the frequencies on the high-luminance side and the total of the frequencies on the low-luminance side are compared with each other. When the exposure evaluation value is obtained without performing the high-luminance processing, and when the total of the frequencies on the low-luminance side is large, the evaluation value of the small area equal to or higher than the high-luminance threshold is set to another predetermined value. Substitute the exposure evaluation value The features. In the automatic exposure control apparatus according to claim 17 of the present invention, in the automatic exposure control apparatus according to any one of claims 10 to 16, when the automatic exposure control is repeatedly performed, the histogram creating means , The interval of the histogram is shifted based on the previous exposure condition. In the automatic exposure control apparatus according to claim 18 of the present invention, in the automatic exposure control apparatus according to claim 17, the histogram creating means determines a difference between a previous exposure condition and a previous exposure condition in a histogram section. It is characterized in that it is converted to a corresponding value, and the interval of the histogram is shifted by the remainder when the converted value is divided by the width of the interval of the histogram. In the automatic exposure control method according to the nineteenth aspect of the present invention, the captured image is divided into a plurality of small regions, and an evaluation value obtained from an integral value of a luminance signal of light incident on the small region from the optical system is obtained. In the automatic exposure control method of performing exposure control by performing high brightness processing, a histogram related to brightness is created from the evaluation value of the small area, and a section in which the frequency of a section of the created histogram is larger than a predetermined frequency threshold is determined. ,
A high-luminance threshold is determined based on the extracted high-frequency section, and a high-luminance process is performed on the luminance integrated value for each of the small regions based on the high-luminance threshold to convert it into an exposure evaluation signal. It is characterized in that exposure control is performed by a signal. According to a twentieth aspect of the present invention, a digital camera includes the automatic exposure control device according to any one of the tenth to eighteenth aspects.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction and operation of an embodiment of the present invention will be described below in detail with reference to the drawings. First Embodiment (1) Configuration of First Embodiment FIG. 1 is a block diagram illustrating a configuration of a digital camera including an automatic exposure control device according to a first embodiment of the present invention. The digital camera of the present invention includes a photographing lens 1, an aperture 2, a CCD
(Charge coupled device) 3, CDS (correlated double sampling)
Circuit 4, process processing circuit 5, A / D converter 6, aperture control unit 7, CCD drive unit 8, system control unit 9, digital signal processing unit 12, memory 14, image data processing unit 17,
It comprises a memory card 18, an image display processing unit 23, and an image display device 24. An image signal of the subject image that has passed through the photographic lens 1 and the aperture 2 is output by a CCD 3 of an image sensor that converts the formed light amount into an electric signal. The output image signal for one image on the CCD 3 is subjected to gain control in the process processing circuit 5 after noise of the CCD 3 is removed by the CDS circuit 4, and then the A / D converter 6
In, the image signal is converted to the optimal sampling frequency (for example,
It is converted into a digital signal at an integer multiple of the subcarrier frequency of the NTSC signal). An iris control unit 7 is connected to the iris 2, and a CCD driving unit 8 is connected to the CCD 3. The aperture control unit 7 is controlled by the system control unit 9 and opens and closes the aperture of the aperture 2 so as to change the diameter of a light beam incident from the imaging lens 1 and reaching the CCD 3. Further, the CCD driving section 8 controls the operation of the CCD 3 so that the system control section 9 can accumulate and take out the electric signal converted by the photographed light image. That is, CCD3
, A shutter operation is performed under the control of the CCD drive unit 8. Therefore, images can be taken with various exposures using these two driving units. A digital signal processing unit 12 is connected to the A / D converter 6, and the digital signal processing unit 12 converts the image signal converted into a digital image signal by the A / D converter 6 into RGB signal conversion, image interpolation, and the like. Perform digital image processing.

The image data created by the digital signal processing unit 12 is once stored in a memory 14 and sent to an image data processing unit 17 where the image data is subjected to image processing such as gamma correction and compression. 18 is stored. Further, the image data created by the digital signal processing unit 12 is sent to the image display processing unit 23, and after image processing such as γ processing is performed, the image data is displayed on an image display device 24 such as an LCD monitor. The user can check the captured image. Further, the digital signal processing unit 12 converts the RGB signal data included in the small area into a luminance value, and integrates the luminance value for each small area. The luminance integrated value for each small area is sent to the system control unit 9. For example, as shown in FIG. 2, the image is divided into 10 × 10 100 small areas, and an integrated value of luminance is obtained for each of the small areas. System control unit 9
Calculates the middle area evaluation value by averaging the luminance integrated values of the small areas included in each middle area. The middle area can be formed by combining the evaluation small areas as in areas 1 to 6 surrounded by the thick line in FIG. The reason why the processing of the middle area is performed by the system control unit 9 is to facilitate changing the shape of the middle area (how to combine small areas) according to the situation. When the high-luminance portion is an integrated value of a small area larger than a certain threshold (high-luminance threshold), the integrated value is replaced with a specified value (high-luminance specified value) to obtain a middle-area evaluation value. When the integrated value of the small area larger than the threshold is
The middle area evaluation value is obtained without being included in the middle area evaluation value. For an image with a large luminance difference, the evaluation area is reevaluated after moving the set area of the middle area where the central photometry or spot photometry is performed in the direction of lower luminance. The system control unit 9 obtains a photographing exposure from each of the middle area evaluation values thus obtained, and controls the CCD driving unit 8 and the aperture control unit 7 to perform exposure control.

(2) Exposure Control of an Image with a Significant Luminance Difference FIG. 3 is a block diagram showing a detailed configuration of the system control unit 9. The system control unit 9 includes a control unit 90, a setting unit 91, a determination unit 92, and a moving unit 93. The control means 90 first calls the setting means 91,
A middle area for judging the luminance difference in the vertical direction or the horizontal direction and a central luminance area for judging the luminance of the central part are newly provided (see FIGS. 4A and 4B). . Here, FIG. 4A shows a middle area for determining a case where there is a luminance difference in the vertical direction, and the two upper and lower middle areas are for luminance difference determination. The middle region of the central portion is a central luminance region for determining whether or not the central portion is dark. FIG. 4B shows a middle area for judging a case where there is a luminance difference in the left-right direction, which is when a digital camera or the like rotates the camera by 90 degrees to capture an image. The two middle regions on the left and right are used for determining a luminance difference, and the middle region in the center is a center brightness region for determining whether or not the center is dark. It is desirable that the middle area for judging the luminance difference is vertically or horizontally separated to some extent. However, since the top and bottom middle areas are determined differently from the center luminance area, as shown in FIGS. 4 (a) and 4 (b), It is good to set. In addition, when determining the luminance difference in the vertical direction, an image having a luminance difference in the horizontal direction is determined by taking an area longer in the horizontal direction as shown in FIG. It is possible to prevent erroneous judgment. Similarly, in the case of judging in the left-right direction, as shown in FIG. As shown in FIGS. 4A and 4B, the same can be said for these central luminance regions.

Next, the control means 90 calls the judging means 92 and obtains the luminance of the luminance difference judging area and the central luminance area for the area set by the setting means 91. At this time, the evaluation value of the central luminance area is different from the high luminance removal processing in the evaluation area for determining the exposure, so that the high luminance removal processing is performed without limiting the number of high luminance parts. If the entire central luminance area is assumed to be bright, the target area disappears when the high luminance part is excluded, but at this time, the determined value is used as an alternative evaluation value, and the luminance integrated values of the small area are collectively collected. Ask. On the other hand, as for the evaluation value of the area where the luminance difference is being determined, it is necessary to look at the raw luminance difference, so that the luminance integrated values of the included small areas are collectively obtained without performing high luminance removal. Furthermore, when the middle area for brightness determination is provided in the vertical direction, the determination means 92 calculates the brightness difference from the brightness integrated value of the upper brightness difference determination area and the brightness integrated value of the lower brightness difference determination area. Ask. The luminance difference is obtained by dividing the larger value of the integrated luminance value by the smaller value of the integrated luminance value. If you are not sure which value will be larger,
After judging which is larger, the luminance difference is obtained. Even in the case where a middle area for luminance determination is provided in the left-right direction, it can be obtained in the same manner as described above. The brightness difference obtained in this way is equal to or more than a certain brightness difference threshold value and is a certain threshold value (hereinafter, referred to as a bright portion threshold value) having a brighter brightness (the larger brightness integration value). If it is smaller than (), the determination means 92 outputs a value of “true”. When this condition is not satisfied, the determination means 92 outputs a value of "true" also when the evaluation value of the central luminance area is equal to or less than a predetermined threshold (hereinafter, referred to as a central threshold).

Next, the control means 90 calls the moving means 93 and moves the area under evaluation when the judgment means 92 outputs a true output. When the judging means 92 outputs “true”, the area under evaluation is moved in the direction in which the darker area under the luminance difference judgment is present. For example, when the upper luminance is high and the lower luminance is low, the evaluation value decreases (darkens) as it goes downward, so that the movement amount of the evaluation area is two luminance difference determination areas and a central luminance area. It is determined appropriately from the evaluation value. Finally, when the area under evaluation is moved, the bright part threshold is changed, and when the area is not moved, the bright part threshold remains unchanged. The control means 90 controls the above means, obtains a photographing exposure from each finally obtained middle area evaluation value, and controls the CCD drive section 8 and the aperture control section 7 to perform exposure control. In the automatic exposure control device having the above-described configuration, the exposure control in the case where a high luminance portion such as the sky is included will be described.

For example, in an image having a luminance difference in the vertical direction as shown in FIG. 5A, the luminance is calculated from the luminance integrated value T1 of the upper luminance difference determination area and the luminance integrated value T2 of the lower luminance difference determination area. Find the difference. The luminance difference is obtained by dividing the larger value of the integrated luminance value by the smaller value of the integrated luminance value.
When a middle area for judging a luminance difference is taken in the vertical direction, the value of T1 generally increases because the sky comes up, and the value of T1 increases.
/ T2, it is not clear which of the left and right values will be larger when taken in the left-right direction, so it is determined which is larger before calculating the luminance difference. When the obtained luminance difference is equal to or greater than a predetermined luminance difference threshold value and the brighter (larger luminance integration value) luminance integration value is smaller than a certain predetermined threshold value (hereinafter, referred to as a bright part threshold value). Then, the evaluation area is moved in the direction in which the darker luminance difference determination area is located (see FIG. 5C). As a result, at the time of the next evaluation, an image is exposed to a dark portion, and a bright image as shown in FIG. Therefore, when a portion higher than the high-brightness threshold occurs due to the entire image being brightened, high-brightness removal becomes possible, and even when the area under evaluation is at the center of the original, FIG.
Can be maintained.

However, even if the whole image becomes bright, FIG.
When the luminance integrated value of the bright part is lower than the high luminance threshold as in (e), the high luminance removal processing is not effective, so the evaluation area is set in the dark part without returning the evaluation area to the original center. It is better to leave it. However, when determining the brightness of the luminance difference determination area, if the bright part threshold is kept fixed, the brightness of the bright part becomes high when the image becomes halfway bright as shown in FIG. 5 (e). In some cases, the image is darker than the luminance threshold and brighter than the bright portion threshold.
In this case, the next exposure is performed in the center and the high luminance removal is not effective, so that the state returns to the state of FIG. 5B, and the image becomes bright or dark (see FIG. 5B). The state shown in FIG. 5E) is repeated, and a so-called hunting state occurs. In order to prevent this from happening, when the evaluation area was moved, the bright area threshold was changed, so that the evaluation area moved to the darker side even in the state of FIG. 5 (e). In this state, hunting of the image can be prevented. According to the experimental results,
This bright part threshold is equal to or higher than the high luminance threshold used to determine whether to exclude the high luminance part (about 0.5 ev (Exposu
re Value)). Therefore, by changing the threshold for determining whether to move the evaluation region (bright portion threshold) depending on whether or not the image is taken with the exposure obtained by moving the evaluation region, hunting during monitoring can be performed. Can be prevented.

By the way, the evaluation value of the high-luminance portion is extremely high, and the evaluation value becomes high even if there is any high-luminance portion in the central luminance region. If there is a high-luminance part in the evaluation area, the vicinity of the center becomes dark despite the center emphasis. Therefore, when obtaining the evaluation value of the central luminance area, unlike the high luminance removal processing in the evaluation area for determining the exposure, the high luminance removal processing is performed without limiting the number of high luminance parts. West,
For example, if the entire central luminance area is bright, the target area disappears when the high luminance part is excluded. At this time, the determined value is used as a substitute evaluation value. On the other hand, since it is necessary to check the raw luminance difference for the evaluation value of the luminance difference determination area, high luminance removal is not performed.
Even when the evaluation value of the central luminance area obtained in this way is equal to or smaller than a predetermined threshold (hereinafter, referred to as a central threshold), the evaluation area moving process is performed. As a result, by performing high luminance removal, the luminance state of the main subject at the center can be known. If the luminance state is dark, the evaluation area can be moved to brighten the main subject. Therefore, it is possible to determine whether or not to move the evaluation area even in an image in which a high-brightness part is reached to the center of the screen.

In the high luminance removal processing for the area under evaluation for determining the exposure as described above, when the high luminance removal processing is performed only when the number of the high luminance parts is equal to or less than a certain number, the evaluation is performed. When the dark part after the middle area is moved is extremely dark, the image becomes too bright in the next exposure and the high luminance part increases, and as a result, the high luminance removal processing is not performed, or If not, it may be too bright overall. For example, when the upper luminance is high and the lower luminance is low as shown in FIG. 6A, the image is moved downward from the evaluation area as shown in FIG. The evaluation value becomes smaller (darkens) as it goes. Therefore, by determining the amount of movement based on the evaluation value of the two luminance difference determination areas and the evaluation value of the central luminance area, it is possible to prevent the image from becoming too bright due to photometry in a dark part. For example, based on the evaluation values of the two luminance difference determination areas and the central luminance area, and the luminance difference obtained from the evaluation values of the respective areas, the evaluation area of FIG. Alternatively, the evaluation value in FIG. 9 and the evaluation value in FIG. 8 are calculated in advance, and an appropriate one is selected. Therefore, it is possible to prevent "the image has become too bright because the evaluation area has been moved too much".

(3) Processing Procedure FIG. 13 is a flowchart for explaining a procedure for moving the evaluation area when the middle area for determining the luminance difference is set in the vertical direction. The same applies to the case where the middle area for judging the luminance difference is set in the left-right direction, so the description is omitted. First, a luminance difference determination area and a central luminance determination area in the upper and lower parts of the image are set (step S10).
0). The evaluation values of the upper and lower luminance difference determination areas are calculated including the high luminance part. In addition, a value obtained by removing a high-luminance portion is obtained for the central-luminance determination region (Step S).
110). After judging which of the two luminance difference determination areas is brighter, it is determined whether the evaluation value of the brighter luminance difference determination area is larger than the bright part threshold (Step S1).
20). If not, the process proceeds to step S140. If it is larger, it is determined whether or not the luminance difference is equal to or greater than the luminance difference threshold (step S130). If the luminance difference is equal to or less than the luminance difference threshold, the process proceeds to step S140. When the luminance difference is equal to or larger than the luminance difference threshold, the process proceeds to step S150. If it is larger, an evaluation area moving process is performed. If the evaluation value of the brighter luminance difference determination area is greater than the bright part threshold or if the luminance difference is smaller than the luminance difference threshold, it is determined whether the evaluation value of the central luminance determination area is equal to or less than the central threshold (step S140). If it is larger, the evaluation area is returned to the default center position. If smaller, the process proceeds to step S150. In the evaluation area moving process of step S150, the moving direction and the moving amount of the evaluation area are determined from the evaluation values of the two luminance difference determination areas and the central luminance determination area. It is determined whether or not the photographed image to be evaluated has been taken with the exposure determined by moving the evaluation area (step S160). When the exposure is determined by moving the evaluation area, the bright part threshold is changed to a value indicating that there is movement (step S170). Otherwise, the bright part threshold is set to a value without movement (step S180). Based on the evaluation value in the area under evaluation determined in this way, the exposure at the next photographing is obtained.

<Embodiment 2> For example, as shown in FIG. 15A, when there is a low-brightness portion such as a bridge girder above a mountain, in FIG. The bridge girder is not hung, but the angle of view is lowered
In the case of (b), both areas during the luminance difference determination become low luminance parts, and it is not determined that there is a luminance difference. That is, as shown in FIG. 15, when there is a low-luminance portion near two luminance difference determination areas, the determination of the presence / absence of a luminance difference may be changed even if the angle of view is slightly shifted. May occur.

(1) Configuration of the Second Embodiment The block diagram showing the configuration of the function of the second embodiment is the same as that of FIG. 1, and the description here is different from the first embodiment. Will be described only. The system control unit 9 receives the luminance integrated value for each small area from the digital signal processing unit 12, creates a histogram based on the luminance distribution,
A high luminance threshold and a high luminance processing method are determined based on the result of the histogram and the exposure conditions at the time of photographing, an exposure control value is obtained by performing high luminance processing, and the CCD drive unit 8 and the aperture control unit 7 are controlled. To control the exposure.

(2) High Brightness Processing Indoors and Outdoors FIG. 16 is a block diagram showing a detailed configuration of the system control unit 9 according to the second embodiment. The system control unit 9 includes a control unit 100, a histogram creation unit 110, an average value calculation unit 120, a high frequency section extraction unit 130, a high luminance value calculation unit 140, and an exposure evaluation value conversion unit 150. Further, the high brightness value calculation means 140 includes a maximum / minimum high frequency section determination means 141 and a high brightness threshold value determination means 142
And The control unit 100 calls the histogram creation unit 110 and creates a histogram from the luminance integrated values of the small areas obtained by the digital signal processing unit 12. Hereinafter, an example in which a histogram is created for a small region (see FIG. 2) divided into 10 × 10 will be described. In this case, since the number of elements with respect to the frequency of the histogram is only 100, if the width of the luminance section is reduced, the total number of sections is increased and the frequency of entering one section is reduced. Can not. Considering that the sensitivity of CCD is around ± 3ev (Exposure Value),
The width of one section is set to 1 ev, and a histogram of nine sections is created in consideration of correction such as exposure correction. Note that it is known that the unit of the section is less affected by the high-luminance part when the unit is performed in the unit of ev. When the exposure evaluation value of the small area is output as a linear value, the histogram is created by converting a section for creating the histogram from an ev value to a linear value. For example, when the linear value at the time of target exposure is 1000, a section of the histogram (shown by the center value in FIG. 17) is set as shown in FIG. Further, by taking into account the difference from the exposure conditions so far, by maintaining a high-frequency section or the like, stable high-luminance processing can be obtained even during continuous exposure control.

Next, the control means 100 calls the average value calculation means 120 and obtains the frequency average value of the histogram created by the histogram creation means 110 from the following equation. Average frequency = Σ _{(i = 1 to maximum section number )} (i × frequency _i ) /
(Total number of frequencies) Next, the control unit 100 calls the high-frequency section extraction unit 130, and selects, in the frequency distribution of the histogram created by the histogram creation unit 110, a section having a frequency greater than a predetermined frequency threshold. Investigate and mark the section. This frequency threshold is determined as follows, depending on the actual sensitivity of the CCD. Frequency threshold = (total number of small areas / total number of sections) × 1.25 Next, the control unit 100 calls the high luminance value calculation unit 140. The high-brightness value calculating means 140 first checks the high-frequency sections marked by the high-frequency section extracting means 130 by the maximum / minimum high-frequency section determining means 141, and selects one of the sections having a frequency higher than the frequency threshold. The smallest section number (hereinafter referred to as a minimum high frequency section) and the largest section number (hereinafter referred to as a maximum high frequency section) are determined (see FIG. 18). If there is no section having a frequency greater than the frequency threshold, information indicating that “section does not exist” is stored. When there is only one section having a frequency higher than the frequency threshold, the minimum high-frequency section and the maximum high-frequency section have the same section number. Furthermore, when there is a sky in a landscape or the like, the brightness of the dark part of the ground is dispersed by a building or the like, and it is difficult to obtain a frequency higher than the frequency threshold. If it is determined that the frequency section is larger than the defined minimum section, the frequency is added from the lower luminance side section of the histogram to the higher luminance side, and each time it is added, the frequency is compared with the frequency threshold. The section at the time of the increase is newly set as the minimum high-frequency section. Indoors, there is not much variation in luminance in low-luminance parts, so whether or not to perform this processing may be determined according to exposure conditions and the like.

Next, the high luminance value calculating means 140 calculates the difference between the maximum high frequency section and the minimum high frequency section by the high luminance threshold value determining means 142, and if the difference is larger than the predetermined section difference threshold value. If it is determined, it is determined that there is a luminance difference, and the high luminance threshold is reset to a value obtained by adding a value determined to the evaluation value corresponding to the minimum high frequency section. If it is determined that the threshold value is small, the high luminance threshold value is reset to a value obtained by adding a predetermined value to the frequency average value obtained by the average value calculation means 120. Next, the control unit 100 controls the exposure evaluation value conversion unit 15
0 is called, and high-luminance processing is performed based on the high-luminance threshold value obtained by the high-luminance value calculation means 140 to obtain an exposure evaluation value. There are the following high-brightness processing methods, but the former has a greater effect of high-brightness removal than the latter. -The exposure evaluation value is obtained without using the evaluation value of the small area equal to or higher than the high luminance threshold. The exposure evaluation value is obtained by fixing the evaluation value of the small area equal to or higher than the high luminance threshold to a certain value. In this case, the exposure threshold is fixed.

In general, in an image having a luminance difference, a portion having a high luminance is the sky and a portion having a low luminance is the ground outdoors, and the subject to be photographed is often the ground portion. For this reason, it is desirable that the exposure control be performed so as to adjust the exposure to the ground as much as possible even if the sky portion is overexposed to some extent.
On the other hand, it is often unclear whether a high-luminance part or a low-luminance part is a main subject indoors, and it is desirable that exposure control be performed so that a high-luminance part is not overexposed indoors as much as possible. In order to perform such exposure control, first, for example, when the exposure condition at the time of shooting is higher than the defined exposure, or when the maximum high-frequency section is larger than the maximum section defined by the exposure condition at the time of shooting, it is determined to be outdoors. Otherwise, decide indoors. When the outdoor shooting is decided, in order to exclude the high brightness part and adjust the exposure to the ground part as much as possible, if the section difference between the maximum high frequency section and the minimum high frequency section is larger than the specified section difference Calculates the exposure evaluation value by performing the former high luminance processing. Otherwise, the latter high brightness processing is performed to obtain an exposure evaluation value. In the case of indoor shooting, when the section difference between the maximum high-frequency section and the minimum high-frequency section is larger than the predetermined section difference, when it is considered that the main subject is on the bright side, high brightness processing is not performed much. When such a high-luminance threshold is set and the main subject is deemed to be on the dark side, the high-luminance threshold is determined normally, and the portion higher than the high-luminance threshold in the high-luminance processing is set to another value (normally, (The same value) so that bright portions are not overexposed. The main subject is determined by comparing the areas of the bright part and the dark part of the captured image, and determining the larger one as the main subject. This area is calculated as the middle section between the maximum frequency section and the minimum frequency section, the sum of the frequencies of the sections larger than the middle section is defined as the brighter area, and the sum of the frequencies of the sections smaller than the middle section is defined as the darker area. Calculate as the area of

(3) Setting of Histogram Section When exposure control is continuously performed to display a photographed image on the LCD screen, the difference between the previous exposure value and the previous exposure value is stored. It is preferable to set the interval when creating the histogram in accordance with the difference between the exposure values. This is because, as described above, since the target value (small area evaluation value) for creating the histogram is small, the width of the section cannot be made too small, and the peak of the high frequency part (the high frequency part) If it is concentrated in a certain section (see FIG. 19A), and the difference between the exposure values corresponds to half of the width of this section, this peak portion becomes 2
This is because there is a possibility that the data is not extracted as a high-frequency section (see FIG. 19B). For this reason, it is necessary to find and hold the peak position as surely as possible. That is, it is important to shift the section of the histogram by the difference between the exposure values so as to maintain the same state of the histogram as before, especially the peak position. In the second embodiment, since the high luminance threshold is determined relatively from the peak position, the peak position only needs to be maintained, and it is only necessary to shift the difference between the exposure values by the remainder of dividing one section length. . For example, if the width of one section is 1 ev and the difference between the previous and previous exposure values is 2.5 ev,
A histogram is created by shifting the histogram creation section by 0.5 ev. In this case, the peak position is +2
It moves to the section higher by ev, but the high luminance threshold is also + 2ev
Since the position shifts to a higher position, the value after the high luminance processing takes almost the same value. Note that it is assumed that the exposure value difference has been subjected to processing including all of the exposure correction and backlight correction by the user.

When actually shifting the histogram by the difference between the exposure values, it is necessary to calculate the section of the histogram corresponding to the difference between the exposure values. If the section has the ev length, a considerable amount of time will be spent on the calculation process. For example, in FIG. 17, the calculation is simple because the value is shown for each 1 ev, but it takes a long time to actually calculate a real value (for example, 0. x ev). However, in the case where exposure control is performed continuously, the processing must be completed within a limited time, and therefore calculation of the histogram section must be avoided as much as possible. Therefore, the interval for shifting the histogram is determined in advance, and the interval of the histogram corresponding to the interval is calculated and stored in advance, so that the calculation time of the interval of the histogram can be omitted. For example, if the section width is 1
In the case of ev, if the shift interval is 0.5 ev, a section of the histogram for each 0.5 ev is defined,
The remainder of the difference between the exposure values may be shifted every 0.5 ev. It should be noted that if the shift interval is set to the interval of other correction processing such as exposure correction and backlight correction, the processing can be easily performed.
Also, when determining whether or not a high-frequency section is a high-frequency section, it is possible to more reliably find the high-frequency section by comparing the sum of two adjacent sections of the section of each 0.5 ev with the frequency threshold. it can. By configuring the second embodiment in this way, even if the histogram has a relatively small number of small areas of about 80 to 200, indoor / outdoor determination is made based on the shooting conditions and the luminance distribution state of the image. Thus, the high luminance threshold can be determined by changing the high luminance threshold in accordance with the image, so that the high luminance processing and the change in the angle of view can be performed reliably, more stably, and more effectively. Also, when creating a histogram, by taking into account the difference from the previous exposure conditions, it is possible to keep high frequency sections, etc., so that stable high brightness processing can be obtained even during continuous exposure control. Can be.

(4) Processing Procedure FIG. 20 is a flowchart for explaining the processing procedure of the system control unit 9 according to the second embodiment. A histogram is created from the evaluation value of the luminance integrated value of the small area (step S200). The interval of the histogram is set so that a high-frequency interval or the like is maintained in consideration of the difference from the previous exposure condition. If the number of elements with respect to the frequency of the histogram is set to be small, the width of the section must be kept moderate so that the frequency of entering one section does not decrease. Therefore, considering that the sensitivity of the CCD is about ± 3 ev, the width of one section is set to 1 ev, and a histogram of nine sections is created in consideration of correction such as exposure correction. When the exposure evaluation value of the small area is output as a linear value, the histogram is created by converting a section for creating the histogram from an ev value to a linear value.

A frequency average value of the histogram is obtained (step S210). A section of the histogram having a frequency higher than the determined frequency threshold is checked (this section is called a high-frequency section) (step S220). The smallest section number (hereinafter, referred to as a minimum high-frequency section) and the largest section number (hereinafter, referred to as a maximum high-frequency section) of the high-frequency sections are determined (step S230) (FIG. 1
8). It is determined whether the minimum high frequency section is larger than the predetermined minimum section (step S240). If it is determined to be large, the frequency is added from the lower luminance side section of the histogram to the higher luminance side, and each time it is added, it is compared with a frequency threshold,
The section at the time when the added value becomes larger than the frequency threshold is newly set as the minimum high-frequency section (step S25).
0). In indoor shooting, since there is not much variation in luminance in a portion with low luminance, whether or not to perform this processing may be determined depending on exposure conditions and the like. The difference between the maximum high-frequency section and the minimum high-frequency section is calculated, and it is determined whether or not the difference is greater than a predetermined section difference threshold (step S26).
0). If it is determined to be large, it is determined that there is a luminance difference, and the high luminance threshold is set to a value obtained by adding a value determined from the evaluation value corresponding to the minimum high frequency section (step S27)
0). On the other hand, if it is determined to be small, the high luminance threshold is set to a value obtained by adding a value determined to the frequency average value obtained in step S210 (step S280). Using the high luminance threshold obtained in this way, for example, in outdoor shooting, the luminance of the sky is considerably high, so that high-luminance processing is performed without using the evaluation value of a small area equal to or higher than the high luminance threshold, and the exposure evaluation value is obtained. Ask for. In addition, for example, in indoor shooting, the evaluation value of a small region equal to or higher than the high luminance threshold is fixed to a certain value (for example, fixed to the exposure threshold), and high luminance processing is performed to obtain an exposure evaluation value. (Step S290) The high-luminance processing can further improve the accuracy by taking into account information such as the distribution of the histogram.
Note that processing for automatic exposure control in the present embodiment,
The processing for setting the evaluation area, the processing for moving the evaluation area, the high-brightness processing using the histogram, and the like can be realized by a program using a microprocessor or the like.

[0032]

As described above, according to the present invention,
Hunting during monitoring can be prevented by changing the threshold for determining whether to move the evaluation area depending on whether or not the image has been taken with the exposure obtained by moving the evaluation area. In addition, it is possible to determine whether or not to move the evaluation area even in an image in which a high-brightness part comes to the screen center. Further, it is possible to prevent the image from becoming too bright due to moving the evaluation area too much. Also,
According to the present invention, it is possible to perform high-luminance processing reliably, more stably, and more effectively by changing the image-capturing conditions according to the image-capturing conditions and the captured image and appropriately setting the high-luminance threshold. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a digital camera of the present invention.

FIG. 2 is a diagram for explaining a relationship between division of an image into small regions and a middle region.

FIG. 3 is a block diagram illustrating a detailed configuration of a system control unit 9 according to the first embodiment.

FIG. 4 is a diagram for explaining setting of a luminance difference determination area and a central luminance area.

FIG. 5 is a diagram for describing processing when a vertical luminance difference determination area is set.

FIG. 6 is a diagram for explaining high luminance processing.

FIG. 7 is a diagram for explaining setting of a general center-weighted metering evaluation area when the luminance difference is small.

FIG. 8 is a diagram for explaining movement of an evaluation area for center-weighted photometry when the lower side of the screen is dark.

FIG. 9 is a diagram for explaining a movement amount of an evaluation area.

FIG. 10 is a diagram for explaining movement of an evaluation area for center-weighted photometry when the upper side of the screen is dark.

FIG. 11 is a diagram for explaining movement of an evaluation area of center-weighted photometry when the right side of the screen is dark.

FIG. 12 is a diagram for explaining movement of an evaluation area for center-weighted photometry when the left side of the screen is dark.

FIG. 13 is a flowchart for explaining a procedure for an evaluation area moving process.

FIG. 14 is a diagram for explaining exposure control of a captured image having high luminance.

FIG. 15 is a diagram for explaining a problem in determining whether or not there is a luminance difference when there is a low-luminance portion near two luminance difference determination areas;

FIG. 16 is a block diagram illustrating a detailed configuration of a system control unit 9 according to the second embodiment.

FIG. 17 is a diagram showing a table for converting a threshold value for each section from an ev value to a linear value when an exposure evaluation value of a small area is output as a linear value.

FIG. 18 is a diagram for explaining a minimum high frequency section and a maximum high frequency section;

FIG. 19 is a diagram for explaining a problem at the time of peak position detection.

FIG. 20 is a flowchart illustrating a processing procedure of a system control unit 9 according to the second embodiment.

[Explanation of symbols]

 Reference Signs List 1 lens 2 aperture 3 CCD (charge coupled device) 4 CDS (correlated double sampling) circuit 5 process processing circuit 6 A / D converter 7 aperture control unit 8 CCD control unit 9 system control unit 12 digital signal processing unit 14 memory 17 Data processing unit 18 Memory card 23 Image display processing unit 24 Image display device 90 Control means 91 Setting means 92 Judgment means 93 Changing means 100 Control means 110 Histogram creation means 120 Average value calculation means 130 High frequency section extraction means 140 High brightness value calculation Means 141 Maximum / minimum high frequency section determination means 142 High brightness threshold value determination means 150 Exposure evaluation value conversion means.

Claims (20)

[Claims] 1. A captured image is divided into a number of small areas, and high-intensity processing is performed based on an evaluation value obtained from an integrated value of a luminance signal of light incident on the small area from an optical system to control exposure control. In the automatic exposure control method to be performed, a plurality of middle areas are set by combining a plurality of the small areas. Are provided as middle regions for brightness difference determination, and the brightness difference of the middle region for brightness difference determination at the facing position is equal to or greater than the brightness difference threshold, and the brighter value of the facing middle region for brightness difference determination is bright. In the case where the brightness is equal to or less than the threshold value, the setting area of the evaluation area to be subjected to the high brightness processing is moved in the direction of lower luminance, and the exposure control is performed using the exposure evaluation value obtained in the evaluation area after the movement. Characteristic automatic exposure control method. 2. The automatic exposure control method according to claim 1, wherein the bright portion threshold is changed depending on whether the evaluation area has been moved. 3. The automatic exposure control method according to claim 1, further comprising the step of: providing a middle area for brightness determination in the center of the image, and moving the set area of the middle area for performing high brightness processing in a direction of lower brightness. Wherein the moving amount of the evaluation area is changed according to the value of the evaluation value between the middle area for brightness determination and the middle area for brightness difference determination in the image central part. . 4. The automatic exposure control method according to claim 3, wherein when the small area in the middle area for luminance determination in the central part of the image is larger than a predetermined threshold, the small area is excluded. An automatic exposure control method, wherein an evaluation value is calculated, and when the evaluation value is equal to or less than a certain threshold, the set area of the area under evaluation is moved. 5. A photographed image is divided into a number of small areas, and high-intensity processing is performed based on an evaluation value obtained from an integrated value of a luminance signal of light incident on the small area from an optical system to perform exposure control. In the automatic exposure control device to be performed, among a plurality of medium regions obtained by combining a plurality of the small regions,
Exposure control means for controlling exposure from an exposure evaluation value obtained from a middle area of an exposure evaluation object, a middle area for determining a luminance difference in upper and lower areas of the captured image from the middle area, or left and right parts of the captured image Setting means for setting the middle area for brightness difference determination in the area of: the brightness difference between the middle areas for brightness difference determination at opposing positions is greater than or equal to a predetermined brightness difference, and the middle area for brightness difference determination facing Determining means for determining that the brighter value is equal to or less than a predetermined threshold value; and moving the set area of the evaluation area to be subjected to high-luminance processing in the direction of lower luminance when the determination means determines that the value is true. When the determination unit determines that the condition is true, performs exposure control using the exposure control value obtained by the exposure control unit with respect to the area under evaluation after the movement by the movement unit. That Features an automatic exposure control device. 6. The automatic exposure control device according to claim 5, wherein the determination unit changes the bright part threshold depending on whether the evaluation area has been moved. . 7. The automatic exposure control device according to claim 5, wherein the setting unit further includes a luminance determination middle area in a central portion of the image, and the moving unit performs high luminance processing. When moving the setting area of the area in the direction of lower luminance, the moving amount of the evaluation area is changed according to the evaluation value of the middle area for luminance determination and the middle area for luminance difference determination in the central portion. Automatic exposure control device characterized by the following. 8. The automatic exposure control device according to claim 7, wherein when the evaluation unit calculates the evaluation value of the middle area for luminance determination in the central part of the image, the evaluation value in the middle area for luminance determination in the central part of the image is calculated. If the small area is larger than a predetermined threshold, the evaluation value is calculated by excluding the small area, and the evaluation value in the middle area for luminance determination in the central portion of the image by the moving means is equal to or less than a certain threshold. An automatic exposure control device wherein the setting area of the area under evaluation is moved at the time of (1). 9. A digital camera comprising the automatic exposure control device according to claim 5. Description: 10. A photographic image is divided into a plurality of small areas, and exposure control is performed by performing high luminance processing based on an evaluation value obtained from an integrated value of a luminance signal of light incident on the small area from an optical system. In the automatic exposure control device, a histogram creating means for creating a histogram relating to luminance from the evaluation value of the small area; and a section where the frequency of a certain section of the histogram created by the histogram creating section is larger than a predetermined frequency threshold (hereinafter, referred to as High-frequency section extraction means for obtaining a high-frequency section); high-luminance value calculation means for determining a high-luminance threshold based on the high-frequency section extracted by the high-frequency section extraction means; Means for performing high-intensity processing of the integrated luminance value of each of the small areas based on the high-intensity threshold value determined by the means and converting the integrated value into an exposure evaluation signal. Automatic exposure control device and performs exposure control by. 11. The automatic exposure control device according to claim 10, wherein the high-brightness value calculating means is a section on the lowest luminance side (hereinafter, referred to as a high-brightness section) among the high-frequency sections obtained by the high-frequency section extracting means. A minimum-high-frequency section determining means for determining a section having the highest luminance (hereinafter referred to as a maximum high-frequency section); and a maximum height determined by the maximum-minimum high-frequency section determining means. An automatic exposure control device comprising: a high-luminance threshold determining unit that determines a high-luminance threshold based on a section difference between a frequency section and a minimum high-frequency section. 12. The automatic exposure control device according to claim 11, wherein the maximum / minimum high frequency section determining means determines a maximum of the histogram when the minimum / high frequency section is larger than a predetermined minimum section. Automatic exposure control, wherein the frequency is sequentially added from the low-luminance section to the high-luminance side, and when the added value is larger than the frequency threshold, the section is reset as a minimum high-frequency section. apparatus. 13. The automatic exposure control device according to claim 11, further comprising an average value calculating unit for obtaining an average value (hereinafter, referred to as a frequency average value) of the histogram created by the histogram creating unit. The high-luminance threshold value determining means, if the section difference between the maximum high-frequency section and the minimum high-frequency section determined by the maximum-minimum high-frequency section determining means is small, the frequency average value determined by the average value calculating means; Is used as a reference value, and when the section difference is large, the minimum high-frequency section is used as a reference value, and a value higher than the reference value by a value determined on the high brightness side is determined as a high brightness threshold. Exposure control device. 14. The automatic exposure control device according to claim 10, wherein said exposure evaluation value conversion means switches high-luminance processing according to a photographing condition and / or a distribution state of said histogram. Automatic exposure control device. 15. The automatic exposure control device according to claim 14, wherein the exposure evaluation value converting means is configured such that an exposure condition at the time of shooting is higher than a predetermined exposure, or the maximum high-frequency section is an exposure at the time of shooting. When the section difference between the maximum high-frequency section and the minimum high-frequency section is greater than the maximum section defined by the condition and the section difference between the maximum high-frequency section and the minimum high-frequency section is greater than the high brightness threshold value, Do not use it to perform high brightness processing to obtain the exposure evaluation value, or
An automatic exposure control device, wherein an exposure evaluation value is obtained by performing high-luminance processing while replacing the evaluation value of the small area with another predetermined value. 16. The automatic exposure control device according to claim 14, wherein the exposure evaluation value converting means sets the exposure condition at the time of shooting lower than a predetermined exposure, and sets the maximum high-frequency section to be lower than the exposure condition at the time of shooting. If the section difference between the maximum high-frequency section and the minimum high-frequency section is smaller than the determined maximum section and the section difference between the maximum high-frequency section and the minimum high-frequency section is larger than the predetermined section difference, an intermediate section between the maximum high-frequency section and the minimum high-frequency section Is calculated, and the sum of the frequencies on the high brightness side and the sum of the frequencies on the low brightness side are compared with each other.If the sum of the frequencies on the high brightness side is large, the exposure evaluation value is calculated without performing the high brightness process. When the sum of the frequencies on the low luminance side is large, the exposure evaluation value is obtained by replacing the evaluation value of the small area equal to or higher than the high luminance threshold with another predetermined value. Exposure control device. 17. The automatic exposure control device according to claim 10, wherein, when automatic exposure control is repeatedly performed, the histogram creating unit performs a control based on a previous exposure condition. An automatic exposure control device, wherein a section of a histogram is shifted. 18. The automatic exposure control device according to claim 17, wherein the histogram creating unit converts a difference between a previous exposure condition and a previous exposure condition into a value corresponding to a section of the histogram. An automatic exposure control device characterized in that the histogram section is shifted by an amount equal to the remainder when the calculated value is divided by the width of the histogram section. 19. A photographic image is divided into a plurality of small areas, and exposure control is performed by performing high luminance processing based on an evaluation value obtained from an integrated value of a luminance signal of light incident on the small area from the optical system. In the automatic exposure control method, a histogram relating to luminance is created from the evaluation value of the small area, a section in which the frequency of a section of the created histogram is larger than a predetermined frequency threshold is determined, and the extracted high-frequency section is determined based on the extracted high-frequency section. A high-intensity threshold is determined, a high-intensity process is performed on the integrated luminance value of each of the small areas based on the high-intensity threshold to convert it into an exposure evaluation signal, and exposure control is performed based on the exposure evaluation signal. Automatic exposure control method. 20. A digital camera comprising the automatic exposure control device according to claim 10. Description: