JP2010157925A - Imaging apparatus, control method thereof and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately perform the exposure control of a face region and background except the face region without causing the breakdown of image quality by the exposure variation of the whole screen by correction when photography is performed using a face detection function. <P>SOLUTION: The face region of an object is detected on the basis of an image signal output from an imaging means, a ratio of a high luminance region whose luminance value is larger than a first value in an imaging screen and a low luminance region whose luminance value is smaller than a second luminance value which is smaller than the first value to the whole imaging screen is calculated on the basis of the luminance information of the imaging screen detected by a luminance information detection means when a ratio of larger one of the calculated high luminance region and the low luminance region to the whole screen is equal to or smaller than a prescribed ratio, exposure control prioritizing that the face region in the imaging screen is made into appropriate exposure is performed, and when the ratio is larger than the prescribed ratio, a low luminance part of a gamma curve is lifted without performing the exposure control prioritizing that the face region is made into the appropriate exposure in the imaging screen. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a function of detecting a human face from a captured image signal.

  Imaging devices such as today's digital cameras and digital camcorders typically have an automatic exposure control (AE) function that automatically determines the exposure based on image information acquired during imaging.

  In automatic exposure control, brightness value information is acquired from a dedicated brightness sensor that measures brightness values, or from an image sensor such as a CCD or CMOS sensor, and the brightness of the screen is controlled by controlling the aperture and shutter speed. The exposure amount is controlled so as to be appropriate.

  In the automatic exposure control, when acquiring luminance value information, the luminance value information is acquired from image information of the entire screen being imaged by using various types of photometry methods. Here, as a photometry method used mainly in imaging devices, a photometry method that performs exposure control in consideration of the value measured from the entire screen (hereinafter referred to as a photometric value), or the screen is divided into multiple areas In addition, there is a photometric method that performs exposure control in consideration of the photometric value in each region. By performing automatic exposure control using these photometry methods, even when the brightness value of the entire screen is bright or the brightness value of some areas is bright, the exposure of the entire screen can be determined appropriately. . Even when the brightness value of the entire screen is dark, the exposure can be converged to an appropriate value by performing the same exposure control method.

  By the way, when performing exposure control only with photometric values acquired from the entire screen, for example, when the brightness value of most of the screen is extremely bright, such as in backlight, the exposure amount can be reduced by exposure control. It is possible to properly expose the entire screen. However, when there is a subject such as a person that the subject wants to shoot in the screen, the subject cannot be properly exposed in the above-described scene such as backlight, and the subject is blacked out.

  Therefore, for example, a technique as described in Patent Document 1 has been proposed in response to the user's need to photograph a subject clearly and brightly even in the above-described backlight state. In Patent Document 1, in order to make the subject exposure appropriate, the photometric value of the area where the subject exists is acquired from the entire screen, and exposure control is performed while taking the acquired photometric value into consideration, thereby brightening the subject exposure. It is corrected. By this method, even if the exposure of the entire screen is appropriate, the entire screen is corrected brightly when the subject is underexposed. Conversely, if the subject is overexposed, the entire screen is corrected to be dark so that the exposure of the entire screen is determined so that the subject is properly exposed. As a result, even in scenes where it has been difficult to control subject exposure, such as backlighting, it is possible to take a picture while appropriately exposing the subject.

  In addition, as an exposure control method using the detected face information of the subject, as shown in FIG. 2, apart from the range set for acquiring the photometric value of the entire screen (hereinafter referred to as a photometric frame), There is a method of setting and using a face-specific metering frame that acquires only the face metering value. Here, the face-specific photometry frame is set according to the position and face size of the face of the subject detected on the screen. Then, compare the photometric value of the face obtained from the face-specific photometric frame with the photometric value of the entire screen, and perform exposure control so that the larger photometric value converges to the appropriate exposure. Control appropriately. As a result, when the brightness value of the face is brighter than the brightness value of the entire screen, exposure control is performed based on the photometric value of the face. It is possible (see Patent Document 2).

  In addition to the above method, as the exposure control method using the photometric value of the face position, the face correction value necessary to converge the exposure of the face to the appropriate value is calculated from the photometric value acquired from the face position of the subject. To do. Then, there is a method of performing exposure control so that the exposure of the face becomes appropriate by considering the calculated face correction value with respect to the photometric value of the entire screen. In this method, as shown in FIG. 3, first, face brightness value information is obtained by photometry from the face position detected in the screen. At the same time, the brightness of the entire screen is measured. Next, a difference value between the obtained photometric value and the face target value set so that the brightness of the face converges to an appropriate value is calculated, a face correction value is calculated from the calculated target value difference, and the entire screen Is added to the photometric value. Finally, by converging the photometric value of the entire screen including the face correction value to the target value of the entire screen, it is possible to determine the exposure of the entire screen with appropriate face exposure.

  However, in these methods using the photometric values of the face, the exposure correction of the entire screen is usually performed in order to make the detected exposure of the face appropriate after making the exposure of the entire screen appropriate. Therefore, this correction control makes it possible to properly expose the face, but in order to correct the entire screen to match the face uniformly, areas other than the face, for example, the background, etc. are whiteout or blackout, and the entire image If you look at it, the image quality will break down.

In view of this, there is a method of preventing the breakdown of the image by controlling the exposure so that the area of the overexposure or underexposure area in the screen to be imaged is minimized. In this method, the gamma curve is changed so as to minimize overexposure or underexposure areas by appropriately correcting the exposure of the face and analyzing the luminance distribution in the screen. Similarly, by changing the gamma curve, a large number of gradations are assigned to the main subject intended to be photographed so that the face can be photographed more clearly. As a result, the image quality of the entire screen can be prevented from being broken, and the exposure of the face can be corrected appropriately (see Patent Document 3).
JP 2003-107555 A JP 2008-70562 A JP 2008-148180 A

  When performing exposure control to converge the exposure of the face to an appropriate value using the photometric value obtained from the photometric frame for the face set at the face position of the subject by the exposure control method described above, from the photometric value of the face A correction value necessary to make the exposure of the face appropriate is calculated. Then, by considering the calculated correction value of the face with respect to the photometric value of the entire screen, it is possible to determine the exposure of the entire screen with appropriate exposure of the face.

  However, when the exposure of the face is made appropriate by the above exposure control method, it is necessary to increase / decrease the luminance value by the amount of face correction for making the exposure of the face appropriate from the exposure of the entire screen which is originally the proper exposure. Therefore, in the case of a scene with a large amount of face correction to make the exposure of the face appropriate, this correction greatly changes the exposure of the entire screen, and overexposure or blackout occurs on the background other than the face, for example, The image quality of the captured image is broken. Therefore, there is a problem that the user is caused to take a broken image in which only the exposure of the face is appropriate.

  In addition, in the method of preventing image breakdown by controlling the exposure so that the area of the overexposure or underexposure area in the screen to be captured is minimized, the gamma curve is changed by the luminance distribution in the screen. This causes a problem that the gradation of the entire screen becomes unnatural.

  The present invention has been made in view of the above-described problems, and the purpose of the present invention is to capture a face region and an image area without causing image quality failure due to a change in exposure of the entire screen due to correction when shooting using the face detection function. It is to enable appropriate exposure control of the background other than the face area.

  In order to solve the above-described problems and achieve the object, an imaging apparatus according to the present invention includes an imaging unit that images a subject and outputs an image signal, and a subject based on the image signal output from the imaging unit. A face detection unit that detects a face area of the image, a luminance information detection unit that detects luminance information of the imaging screen, and a luminance in the imaging screen based on the luminance information of the imaging screen detected by the luminance information detection unit Calculation means for calculating a ratio of a high luminance area whose value is larger than the first value and a low luminance area whose luminance value is smaller than the first value to the entire imaging screen. And control means for performing exposure control based on brightness information of the imaging screen, wherein the control means is the larger of the high brightness area and the low brightness area calculated by the computing means. Before When the ratio to the entire imaging screen is equal to or less than a predetermined ratio, exposure control is performed with priority given to appropriate exposure of the face area in the imaging screen. When the ratio is larger than a predetermined ratio, the face in the imaging screen The low-luminance part of the gamma curve is lifted without performing exposure control giving priority to appropriate exposure of the area.

  An image pickup apparatus control method according to the present invention is an image pickup apparatus control method including an image pickup unit that picks up an image of a subject and outputs an image signal, and the subject is based on the image signal output from the image pickup unit. A brightness detection in the imaging screen based on the brightness information of the imaging screen detected in the brightness information detection step, a brightness information detection step of detecting brightness information of the imaging screen, and a brightness information detection step of detecting brightness information of the imaging screen A calculation step of calculating a ratio of a high luminance area whose value is larger than the first value and a low luminance area whose luminance value is smaller than the first value to the entire imaging screen. And a control step of performing exposure control based on the luminance information of the imaging screen, and in the control step, whichever of the high luminance region and the low luminance region calculated in the calculation step is larger When the ratio of the one to the entire imaging screen is equal to or less than a predetermined ratio, exposure control is performed with priority given to appropriate exposure of the face area in the imaging screen. When the ratio is larger than the predetermined ratio, the imaging screen The low luminance portion of the gamma curve is raised without performing exposure control giving priority to making the face area in the proper exposure.

  According to the present invention, when shooting using the face detection function, exposure control of the face area and the background other than the face area is appropriately performed without causing image quality failure due to the exposure change of the entire screen due to the correction. Is possible.

  Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of an imaging apparatus 100 according to an embodiment of the present invention.

  In FIG. 1, reference numeral 1 denotes a lens that guides light incident from the outside of the imaging apparatus 100 to the inside of the imaging apparatus 100. FIG. 1 illustrates a single lens in a simplified manner. Consists of lenses. Reference numeral 2 denotes a stop for adjusting the amount of incident light. Reference numeral 3 denotes an aperture drive motor that drives the aperture 2. Reference numeral 4 denotes an aperture state detection circuit that detects the drive state of the aperture 2. Here, in the present embodiment, a form in which the diaphragm 2 is disposed is shown, but in the case of an imaging apparatus in which the diaphragm 2 is not disposed, the diaphragm drive motor 3 and the diaphragm state detection circuit 4 may not be provided. Reference numeral 5 denotes an ND filter for attenuating light incident from the lens. An ND filter driving motor 6 drives the ND filter 5. Reference numeral 7 denotes an ND filter drive detection circuit that detects the drive state of the ND filter 5. Here, in the present embodiment, the form in which the ND filter 5 is arranged is shown. However, in the case of an imaging apparatus in which the ND filter 5 is not arranged, the ND filter drive motor 6 and the ND filter drive detection circuit 7 may not be provided.

  Reference numeral 8 denotes an image sensor that images a subject. The image sensor 8 of the present embodiment is not limited to the type of image sensor such as a CCD or CMOS sensor. Reference numeral 9 denotes a CDS (Correlated Double Sampling) / AGC (Auto Gain Control) circuit that samples and amplifies an image signal based on charges stored in each pixel of the image sensor 8. Reference numeral 10 denotes an A / D conversion circuit that converts an image signal output from the CDS / AGC circuit 9 into a digital signal. Reference numeral 11 denotes a digital signal processing circuit that performs various signal processing on the digital image signal output from the A / D conversion circuit 10.

  Reference numeral 12 denotes a microcomputer that comprehensively controls the operation of the imaging apparatus 100 of the present embodiment. For example, the microcomputer 12 receives information such as luminance and color from the digital signal processing circuit 11 and performs various arithmetic processes. Reference numeral 13 denotes an aperture mechanism drive unit that supplies power to the aperture drive motor 3 based on control by the microcomputer 12. Reference numeral 14 denotes an image sensor driving unit that supplies drive pulses and the like for driving the image sensor 8 based on control by the microcomputer 12. An ND filter mechanism drive unit 15 supplies power to the ND filter drive motor 6 based on control by the microcomputer 12. In the case of an imaging apparatus that does not include the diaphragm 2, the diaphragm mechanism driving unit 13 may not be provided. Similarly, in the case of an imaging apparatus that does not include the ND filter 5, the ND filter mechanism driving unit 15 may not be provided. As described above, exposure control is performed by the microcomputer 12 controlling various driving units.

  Reference numeral 16 denotes a face detection circuit that detects the face area of the subject in the screen from the information of the entire image signal. Reference numeral 17 denotes a luminance information detection circuit that detects a luminance value based on digital image data sent from the microcomputer 12. Reference numeral 18 denotes a luminance information calculation circuit that calculates the luminance value detected by the luminance information detection circuit 17. Reference numeral 19 denotes a gamma control circuit that controls the gamma curve. Reference numeral 20 denotes a recording medium that records an image picked up by the image pickup apparatus 100.

  In the imaging apparatus 100, in the conventional operation, when performing exposure control for appropriately exposing the face area, the imaging element 8 senses the subject to be imaged, and the charge stored in each pixel of the imaging element 8 is output as an image signal. Then, it is sampled and amplified by the CDS / AGC circuit 9. Then, it is converted into a digital signal by the A / D conversion circuit 10 and sent to the digital signal processing circuit 11. In the digital signal processing circuit 11, various signal processing is performed on the digital image signal output from the A / D conversion circuit 10, and the microcomputer 12 sends the result to the face detection circuit 16. Then, the face detection circuit 16 detects the position of the face area that is considered to be the face of the subject in the screen and the size of the face area from the image signal.

  Thereafter, when the face detection circuit 16 detects the position and size of the face area of the subject, the luminance information detection circuit 17 acquires the photometric value in order to acquire the luminance value of the face area in the screen. The photometric value of the photometric face area is calculated by the luminance information calculation circuit 18 and normalized. At this time, the photometric value of the entire screen is also acquired by the luminance information detection circuit 17 and is calculated by the luminance information calculation circuit 18.

  Then, the microcomputer 12 calculates a difference value between the face photometric value and the face target value set so that the exposure of the face area converges to an appropriate value. Thereafter, a face correction value is calculated by the microcomputer 12 from the calculated difference value and added to the photometric value of the entire screen. Also, the photometric value of the entire screen including the face correction value is converged to the target value of the entire screen, thereby determining the photometric value of the entire screen in which the exposure of the face area is appropriate.

  In contrast to such conventional control, in the operation of the imaging apparatus 100 of the present embodiment, when performing exposure control for appropriately exposing the face area, the following is performed. First, the imaging element 8 senses the subject to be imaged, and the electric charge stored in each pixel of the imaging element 8 is output as an image signal, and is sampled and amplified by the CDS / AGC circuit 9. Then, it is converted into a digital signal by the A / D conversion circuit 10 and sent to the digital signal processing circuit 11. In the digital signal processing circuit 11, various signal processing is performed on the digital image signal output from the A / D conversion circuit 10, and the microcomputer 12 sends the result to the face detection circuit 16. Then, the face detection circuit 16 detects the position of the face area of the subject in the screen and the size of the face area from the image signal.

  Thereafter, when the face detection circuit 16 detects the position and size of the face area of the subject, the luminance information detection circuit 17 acquires the photometric value in order to acquire the luminance value of the face area in the screen. The photometric value of the photometric face area is calculated by the luminance information calculation circuit 18 and normalized. At this time, the photometric value of the entire screen is also acquired by the luminance information detection circuit 17 and is calculated by the luminance information calculation circuit 18.

  Then, the microcomputer 12 calculates a difference value between the face photometric value and the face target value set so that the exposure of the face area converges to an appropriate value. Thereafter, a face correction value is calculated by the microcomputer 12 from the calculated difference value and added to the photometric value of the entire screen. Also, the photometric value of the entire screen including the face correction value is converged to the target value of the entire screen, thereby determining the photometric value of the entire screen in which the exposure of the face area is appropriate. At this time, the microcomputer 12 detects a high-brightness pixel region (high-brightness region) and a low-brightness pixel region (low-brightness region) in the imaging screen. When the ratio of the detected area to the entire imaging screen exceeds a preset threshold, correction control is stopped even when the exposure of the face area is not appropriate.

  This prevents the image quality from failing due to correction such as overexposure of the background or blackout. Finally, when the exposure of the face area is under after the correction control is stopped, the brightness of the face area that could not be properly achieved by stopping the correction control by lifting the low luminance part of the gamma curve by the gamma control circuit 19 Make up.

  In the present embodiment, for the sake of easy understanding, FIG. 1 shows the configuration of all independent circuit units. However, all or a part of the configuration may be built in the microcomputer 12.

  Next, a control operation in the imaging apparatus 100 according to the present embodiment will be described.

  FIG. 4 is a flowchart showing a control operation in the imaging apparatus 100 according to the present embodiment. Specifically, FIG. 4 shows exposure control using face information in the imaging apparatus 100. FIG. 5 shows an actual operation. The description will be made with reference to FIGS.

  In the present embodiment, the photometric value of the entire screen is acquired in step S101. In step S102, an evaluation value for exposure control is calculated from the acquired photometric value. Thereafter, when performing exposure control using face information, in step S103, it is determined whether or not the face area of the subject exists in the screen imaged by the face detection circuit 16. As a result of the determination in step S103, if it is determined that the face area of the subject does not exist in the screen, the face correction value is not calculated and exposure control for the entire entire screen is performed in step S113. Exit.

  On the other hand, if it is determined in step S103 that the face area of the subject exists in the screen, the process proceeds to step S104. In step S104, a face photometric frame is set at the position of the face area detected in step S103, and the face photometric value is acquired by the luminance information detection circuit 17. At this time, the acquired face photometric value may be acquired from a plurality of face regions. After that, the photometric face photometric value is calculated by the luminance information calculation circuit 18 and normalized. In step S105, a face correction value is calculated. Thereafter, in step S106, 1. of FIG. As shown in FIG. 5, the luminance distribution in the imaging screen is analyzed by detecting a region in the imaging screen that falls within the luminance value range of high luminance or low luminance preset by the microcomputer 12. The brightness value range of high brightness or low brightness is a second value set for low brightness whose brightness value is larger than the first value set for high brightness or smaller than the first value. It is a range smaller than the value. In step S107, the ratio of the detected high-luminance pixel and low-luminance pixel to the entire imaging screen is calculated.

  Next, in step S108, 2. of FIG. As shown in FIG. 6, it is determined whether or not the ratio of the high luminance part or the low luminance part calculated in step S107 exceeds a predetermined ratio. Note that the predetermined ratio is a criterion for determining whether or not the image quality is considered to be broken due to overexposure or blackout in the background, and may be set in advance or set by the user It may be. As a result of the determination in step S108, if it is determined that the ratio of the higher luminance portion or the lower luminance portion to the larger screen is less than or equal to the predetermined ratio, the microcomputer 12 performs photometry on the entire screen in step S110. The face correction value is added to the value. At this time, the face correction values are divided and added one by one without adding all the values at once. Thus, by reducing the change in the exposure of the entire screen due to the correction, stable exposure control can be performed even when the brightness value of the detected face area changes abruptly. If it is determined in step S108 that the predetermined ratio has been exceeded, face correction control (exposure by giving the face area a proper exposure by adding the face correction value to the photometric value of the entire screen) Control). In other words, the ratio of the area where the brightness value such as the background in the screen is overexposed or underexposed is calculated, and if this ratio exceeds the predetermined ratio, the image quality of the entire screen will be destroyed if the exposure is adjusted to the face area. Therefore, the face correction value is not further added to the photometric value of the entire screen. This prevents the image quality of the entire screen from failing.

  After the face correction control is stopped in step S109, it is determined in step S111 whether the brightness value of the face area acquired by the brightness information detection circuit 17 is under the set face target value. If it is determined in step S111 that the exposure of the face area is under, In step S112, the gamma control circuit 19 is used to raise the gamma curve of the low luminance part to increase the brightness of the low luminance part. This compensates for the shortage of exposure in the face area caused by stopping the correction control in order to suppress the image quality failure of the entire screen.

  Lastly, in step S113, the photometric value of the entire screen including the added face correction value is converged to the target value of the entire screen to determine the photometric value of the entire screen in which the exposure of the face area is appropriate.

  Note that the processing from S101 to S113 is repeatedly performed, and when the processing of S113 is performed, the processing proceeds to S101. Therefore, the divided face correction values are added each time S110 is performed, and exposure control is performed in S113 every time a face correction value is added.

  In S110, an upper limit value is set for the face correction value to be added at one time, and if the face correction value calculated in S105 is equal to or less than the set upper limit value, it is added to the photometric value of the entire screen without being divided. May be.

  As described above, according to the present embodiment, the conventional exposure control at the time of face detection has a high brightness on the entire screen for a scene that requires a large correction amount such that exposure other than the face area breaks down at the time of face correction. The correction control is stopped according to the ratio of the area of the low-brightness area in the screen. As a result, it is possible to prevent the image quality of the captured image from being broken due to correction such as overexposure of the background other than the face area or blackout. Also, if the exposure of the face area is insufficient, only the low luminance part of the gamma curve is lifted by the gamma control circuit, for example, the high luminance part of the background is affected by raising the gamma value higher than usual only in the low luminance part. It is possible to brightly correct a dark face without giving an image.

  Exposure control using the face correction value in the imaging apparatus 100 of the present embodiment is executed by the series of processes in steps S101 to S113 described above.

  Finally, the characteristic operations of the imaging apparatus 100 of the present embodiment are summarized as follows.

  First, the microcomputer corrects the detection of the high-luminance part and the low-luminance part of the entire screen, calculates the ratio in the screen, and stops the face correction control giving priority to the proper exposure of the face area. In other words, whiteout and blackout in the screen are detected, and a limit is set in the face correction control so that the ratio of the whiteout and blackout area in the entire screen falls within a predetermined ratio. This suppresses image quality failure of the entire captured image, such as overexposure of the background and blackout. In addition, the shortage that the face area cannot be properly exposed by the face correction control is compensated by raising the gamma curve of the low luminance part by the gamma control. Thereby, it is possible to perform exposure control in consideration of correction of exposure of the face area by face detection while maintaining the image quality of the entire screen.

  4 and 5, the case where the luminance value of the face area of the subject is lower than the luminance value of the entire shooting screen has been described. However, the face correction value for darkening the bright face area is calculated and the entire screen is calculated. Even when the exposure control is performed, the same control can be performed. In this case, the determination of whether or not the brightness value of the face area in S111 in FIG. 4 is under the set face target value may be omitted. However, when performing exposure control to darken a bright face area, the face area may not be properly exposed. That is, since the face area exposure is not corrected by changing the gamma curve as shown in FIG. 5 after the face correction control is stopped in S109, a case where the exposure of the face area is brighter than the appropriate exposure may be maintained. Even in such a case, compared to the conventional exposure control, the exposure of the background other than the face area and the face area can be suppressed because the image quality of the entire screen can be suppressed while bringing the exposure of the face area close to the appropriate exposure. Can be performed appropriately.

  In addition, in S111 of FIG. 4, instead of determining whether the brightness value of the face area is under the set face target value, is the face area brightness value over the set face target value? You may make it judge whether or not. In that case, in step S112, the gamma curve of the high luminance portion may be controlled to be lower than the normal time, instead of raising the gamma curve of the low luminance portion as shown in FIG.

(Other embodiments)
The object of each embodiment is also achieved by the following method. That is, a storage medium (or recording medium) in which a program code of software that realizes the functions of the above-described embodiments is recorded is supplied to the system or apparatus. Then, the computer (or CPU or MPU) of the system or apparatus reads and executes the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but the present invention includes the following cases. That is, based on the instruction of the program code, an operating system (OS) running on the computer performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  Furthermore, the following cases are also included in the present invention. That is, the program code read from the storage medium is written into a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion card or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

  When the present invention is applied to the above storage medium, the storage medium stores program codes corresponding to the procedure described above.

1 is a diagram illustrating a schematic configuration of an imaging apparatus according to an embodiment of the present invention. It is a figure which shows the relationship between a face photometry frame and the photometry frame of the whole screen. It is a figure which shows the exposure control method using the face information used as one premise in one Embodiment of this invention. It is a flowchart which shows control of the imaging device of one Embodiment of this invention. It is a figure which shows typically control of the imaging device of one Embodiment of this invention.

Explanation of symbols

1 lens (shown as one for simplicity)
2 Aperture 3 Aperture Drive Motor 4 Aperture State Detection Circuit 5 ND Filter 6 ND Filter Drive Motor 7 ND Filter Drive Detection Circuit 8 Image Sensor 9 CDS / AGC Circuit 10 A / D Conversion Circuit 11 Digital Signal Processing Circuit 12 Microcomputer 13 Aperture Mechanism Driving unit 14 Image sensor driving unit 15 ND filter mechanism driving unit 16 Face detection circuit 17 Luminance information detection circuit 18 Luminance information calculation circuit 19 Gamma control circuit 20 Recording medium 100 Imaging device

Claims (4)

Imaging means for imaging a subject and outputting an image signal;
Face detection means for detecting a face area of a subject based on an image signal output from the imaging means;
Luminance information detecting means for detecting luminance information of the imaging screen;
Based on the luminance information of the imaging screen detected by the luminance information detecting means, a high-luminance region having a luminance value larger than the first value in the imaging screen and a luminance value smaller than the first value Calculating means for calculating a ratio of the low luminance area smaller than the second value as a value to the entire imaging screen;
Control means for performing exposure control based on luminance information of the imaging screen,
When the ratio of the larger one of the high luminance area and the low luminance area calculated by the arithmetic means to the entire imaging screen is equal to or less than a predetermined ratio, the control means If the exposure control gives priority to proper exposure and is greater than a predetermined ratio, the brightness of the gamma curve is low without performing exposure control giving priority to proper exposure of the face area in the imaging screen. An imaging apparatus characterized by lifting a part.   When the ratio of the high-luminance area to the entire imaging screen is larger than the ratio of the low-luminance area and larger than a predetermined ratio, the control means is configured to adjust the gamma curve so that the face area is properly exposed. The imaging apparatus according to claim 1, wherein the low-luminance part is lifted. A method for controlling an imaging apparatus including imaging means for imaging a subject and outputting an image signal,
A face detection step of detecting a face area of a subject based on an image signal output from the imaging means;
A luminance information detecting step for detecting luminance information of the imaging screen;
Based on the luminance information of the imaging screen detected in the luminance information detection step, a high-luminance region having a luminance value larger than the first value in the imaging screen and a luminance value smaller than the first value A calculation step of calculating a ratio of a low luminance area smaller than a second value as a value to the entire imaging screen;
A control step of performing exposure control based on luminance information of the imaging screen,
In the control step, when the ratio of the larger one of the high luminance area and the low luminance area calculated in the calculation step to the entire imaging screen is equal to or smaller than a predetermined ratio, the face area in the imaging screen If the exposure control gives priority to proper exposure and is greater than a predetermined ratio, the brightness of the gamma curve is low without performing exposure control giving priority to proper exposure of the face area in the imaging screen. A method for controlling an imaging apparatus, wherein the part is lifted.   A program for causing a computer to execute the control method according to claim 3.

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