JP2019118115A - Exposure control device, exposure control method, and program - Google Patents

Abstract

To prevent influences of exposure caused by erroneous detection or fluctuation of face detection and to suppress influences of exposure in a case where an object passes in front of a subject.SOLUTION: A face detection circuit 116 detects a face region from an image obtained by imaging a subject, and a camera microcomputer 101 performs exposure control based on a photometric result in accordance with a first photometric method that performs photometry while weighting the face region, or a second photometric method different from the first photometric method. In the first photometric method, photometry is performed while weighting the face region meeting a predetermined condition in a case where one or more face regions are detected by the face detection circuit. While exposure control is performed in accordance with the first photometric method, in a case where a new face region meeting the predetermined condition is detected in a predetermined period after the face region meeting the predetermined condition is not detected any longer, the camera microcomputer performs exposure control again while weighting the newly detected face region by using the first photometric method. In a case where a new face region meeting the predetermined condition is not detected in the predetermined period, exposure control is performed by using the second photometric method.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an exposure control apparatus, an exposure control method, and a program, and more particularly to exposure control in moving image shooting.

  In general, when photographing a still image in an imaging device such as a digital camera, the photographing screen is divided into a plurality of areas and light measurement is performed as the light measurement. There is an evaluation photometry in which the exposure is determined according to the balance between the bright part and the dark part in a plurality of areas, and further, there is spot photometry in which photometry is performed only in a specific narrow area. The position information of the focus detection area for focusing is used when determining the photometric area or determining the weighting for each divided area in any of the side lights.

  On the other hand, in photometry used for moving image shooting, exposure control is performed with emphasis on the stability of exposure with respect to movement of a subject and change in composition. For this reason, there is an imaging apparatus provided with a center-weighted average metering, which weighs a relatively wide range on average while placing weights in the center of the screen, as a dedicated metering mode.

  Furthermore, in recent years, a method of detecting and tracking the face of a person from a captured image is used in an imaging apparatus. Then, at the time of moving image shooting, the imaging device performs control to switch photometry from center-weighted average photometry to face evaluation photometry in which weighting is applied to divided areas of the face part (photometric divided areas) when a human face is detected. There is.

  In this imaging device, if the face of a person can not be detected, exposure control is performed using central weighted average metering. In this case, for example, in a composition in which the center of the screen is bright and a person with a slight backlight is present at the edge of the screen, overexposure is suppressed at the center of the screen and exposure of an appropriate level is obtained. It becomes an exposure of

  In addition, when the state in which whether or not the face of the person can be detected is subtle continues, that is, when the face detectable state and the face undetectable state alternately appear, the above-described imaging device performs face evaluation photometry And center-weighted average metering will be switched intermittently. As a result, the exposure changes intermittently, resulting in a moving image with flickering brightness.

  In order to suppress the occurrence of photometric switching as described above, there is known an imaging apparatus that determines a photometric method with reference to a face detection result by chattering processing, that is, a plurality of face detection results. reference).

Unexamined-Japanese-Patent No. 2010-41399

  However, in order to suppress the fluctuation of the face detection result by chattering processing, there are the following problems.

  When another object crosses the screen while shooting a moving image with a composition with a person on the screen, the result of referring to the face detection results of multiple times is determined that another object starts to cross in front of the person and face detection is not possible There is a delay before the results come out. For this reason, between the start of crossing of another object in front of the person and the determination result that face detection is not possible, the brightness of the crossed object is regarded as the brightness of the person's face and face evaluation photometry is performed. There is a phenomenon that exposure control is influenced by an object.

  For example, if the object crossed is black, the face that has been properly exposed may be temporarily overexposed, resulting in an uneven exposure. In particular, when a black object crosses the main subject (main face) in a shooting scene in which two persons are present, the exposure for the other subject is deviated from the appropriate state.

  Therefore, it is an object of the present invention to prevent the influence of exposure caused by false detection and fluctuation of face detection, and to suppress the influence of exposure when an object crosses, an exposure control method, and a program To provide.

  In order to achieve the above object, an exposure control apparatus according to the present invention comprises: detection means for detecting a face area from an image obtained by imaging a subject; and first photometry for performing photometry by weighting the face area Exposure control means for performing exposure control on the basis of a photometry result by a second photometry method different from the method or the first photometry method, and in the first photometry method, one or more of the detection means When the face area is detected, the face area satisfying a predetermined condition is weighted to perform photometry, and the exposure control unit performs the exposure control according to the first photometry method. If the detection unit detects a new face area that satisfies the predetermined condition in a predetermined period after the face area that satisfies the predetermined condition is not detected, the newly detected face area is weighted. The first photometric method The exposure control is performed again using the second photometry method when the detection unit does not detect a new face area that satisfies the predetermined condition in the predetermined period. It is characterized by

  According to the present invention, it is possible to prevent the influence of exposure caused by false detection and fluctuation when detecting a specific area such as a face area, and to suppress the influence of exposure when an object crosses.

It is a figure for demonstrating an example of the moving image imaging | photography in the conventional imaging device, (A) is a figure which shows the image of the state which was able to detect the face, (B) is a figure which shows the image of the state which can not detect a face. . It is a figure for demonstrating the other example of the moving image photography in the conventional imaging device, (A) is a figure which shows the state which the object crossed, when there are one person, (A) is two persons. It is a figure which shows the state which the object crossed in the case. It is a figure which shows the structure about an example of the imaging device by embodiment of this invention. It is a flowchart for demonstrating the imaging operation performed with the camera shown in FIG. It is a flowchart for demonstrating the exposure control shown in FIG. It is a flowchart for demonstrating the face use determination processing shown in FIG. It is a figure for demonstrating the face list memorize | stored in the camera microcomputer shown in FIG. 1, (a) is a figure which shows an example of a face list, (b) is a figure which shows the face list after rearrangement. It is a flowchart for demonstrating the fluctuation removal process shown in FIG. It is a figure for demonstrating the effect by the fluctuation removal process demonstrated in FIG.

  Hereinafter, an example of an imaging device according to an embodiment of the present invention will be described with reference to the drawings.

  Here, before describing an imaging apparatus according to an embodiment of the present invention, first, exposure control in the case where moving image shooting is performed in a conventional imaging apparatus will be outlined.

  FIG. 1 is a diagram for explaining an example of moving image shooting in a conventional imaging device. FIG. 1A is a view showing an image in a state in which a face is detected, and FIG. 1B is a view showing an image in a state in which a face can not be detected.

  Now, as shown in FIG. 1A, it is assumed that a moving picture is taken of a composition in which the center of the screen is bright and a person with a slight backlight is present at the end of the screen. Here, when the image pickup apparatus can correctly detect the face (specific region) of a person, the image pickup apparatus performs exposure control using the above-described evaluation photometry. As a result, it is possible to eliminate the backlighting state in the face of the person and obtain a moving image with an appropriate exposure for the face portion.

  On the other hand, if face detection can not be performed because the face part is dark in the image, the face part is small, or face feature points can not be extracted due to the face orientation, the imaging device performs exposure control using center-weighted average metering. . As a result, although the appropriate exposure in which the overexposure is suppressed is obtained for the high-intensity part in the central part of the screen, the exposure is reduced for the face part of the person (see FIG. 1B).

  Furthermore, when a state where the face of the person can not be detected intermittently occurs, the imaging apparatus intermittently switches between the evaluation photometry and the center-weighted average photometry to perform exposure control. In this manner, when the photometry is switched intermittently, the exposure changes repeatedly and the brightness of the moving image flickers.

  There is an imaging apparatus in which a face detection result is subjected to chattering processing in order to suppress such flickering in the brightness of a moving image. In this imaging device, the photometric method is determined with reference to a plurality of detection results.

  FIG. 2 is a diagram for explaining another example of moving image shooting in a conventional imaging device. FIG. 2A is a view showing a state in which an object is crossed when there is only one person, and FIG. 2A is a view showing a state in which an object is crossed when there are two people. .

  As shown in FIG. 2A, it is assumed that another object (here, a car) crosses the screen while shooting a moving image with a composition in which one person exists on the screen. In the image pickup apparatus, the photometric method is determined based on a plurality of times of face detection results, so that the determination of the photometric method is delayed. As a result, a phenomenon occurs in which the exposure control is influenced by another object.

  If the color of another object is black, a moving image with a proper exposure on the face may be temporarily overexposed, resulting in a blur in the exposure. In particular, as shown in FIG. 2B, in a composition in which two persons are present, when a black object crosses the main subject (person on the left side in the figure), the other object (person on the right side in the figure) The exposure will be inappropriate.

  FIG. 3 is a view showing the configuration of an example of the imaging apparatus according to the embodiment of the present invention.

  The illustrated imaging apparatus is, for example, a digital camera (hereinafter simply referred to as a camera), and includes a camera body 100 and a lens unit 200 of an interchangeable lens type.

  The camera body 100 includes a microcomputer (CCPU: hereinafter referred to as a camera microcomputer) 101, and the camera microcomputer controls the entire camera. In the camera body 100, on the optical axis (optical path) of the lens unit 200, an imaging device 102 such as a CCD or a CMOS image sensor is disposed. Although not shown, the image pickup device 102 is provided with an infrared cut filter and a low pass filter. Then, a subject image (optical image) is formed on the image sensor 102 via the lens unit 200, and the image sensor 102 outputs an image signal (analog signal) corresponding to the optical image.

  An image signal output from the image sensor 102 is converted into a digital image signal by an A / D converter (A / D) 109. Then, the digital image signal is sent to the signal processing circuit 111. The signal processing circuit 111 processes the digital image signal based on a predetermined parameter to generate image data.

  A photometry circuit (AE) 106 performs photometry control, which will be described later, according to image data which is an output of the signal processing circuit 111. Further, the focus detection circuit (AF) 107 performs focus detection control described later based on the image data.

  The gain switching circuit 108 is a circuit for switching the gain in the image sensor 102. The switching of the gain by the gain switching circuit 108 is controlled by the camera microcomputer 101 in accordance with the photographing condition and the input of the photographer.

  A timing generator (TG) 110 synchronizes the input of the image signal which is the output of the image sensor 102 with the timing of A / D conversion by the A / D converter 109 under the control of the camera microcomputer 101. Here, description of a memory for storing image data obtained as a result of signal processing by the signal processing circuit 111 is omitted.

  The lens mount 130 is an interface with a lens microcomputer 201 described later, and has a communication terminal for performing data communication between the lens microcomputer 201 and the camera microcomputer 101. By the data communication, the camera microcomputer 101 can determine the type of the lens unit 200 mounted on the camera body 100 and the state thereof.

  The input unit 112 includes, for example, a shooting standby button (standby button) 114 and a recording start button (recording button) 115 for setting the camera in a shooting standby state. Furthermore, although not shown, the input unit 112 is a switch or button for switching between the AF area arbitrary selection mode and the multipoint / face tracking mode, and a shooting mode switching dial for switching between the shutter speed priority mode and the aperture priority mode Etc. The user can input camera settings and the like by means of the input unit 112.

  The display unit 113 includes a liquid crystal device, a light emitting element, and the like, and displays the set mode and other information regarding shooting. The face detection circuit 116 detects a face of a person (face area: specific area) in image data which is an output of the signal processing circuit 111, and sends a face area detection result to the camera microcomputer 101. The face detection circuit 116 identifies the number of face areas in the image data, the position and size of each face area in the image data, and the orientation of the face area.

  As a face area detection method, for example, a method of extracting face characteristic parts such as eyes, nose, and mouth in image data to specify a face area is used. Furthermore, skin color data may be extracted from image data, and a region determined as a skin color range may be detected as a face region. In addition, the face area may be detected by focusing on the contour of the face area and using elliptical shape information indicating the outline.

  As shown, the camera microcomputer 101 is provided with a face use determining circuit 117. The face use determining circuit 117 determines whether to use the face area detection result for the determination of exposure as described later. The determination result (face use determination result) by the face use determination circuit 117 is used for photometric control in the photometry circuit 106.

  The lens unit 200 is provided with a microcomputer (LPU: lens microcomputer) 201, and the lens microcomputer 201 controls the operation of the lens unit 200. That is, the lens microcomputer 201 controls the lens unit 200 and performs various condition determinations.

  The lens unit 200 includes a lens group 202 having a plurality of lenses. The lens group 202 includes a focus lens that is disposed movably along the optical axis and performs focus adjustment.

  A lens drive unit 203 is an actuator for moving an optical system for focus detection and focus alignment in the lens group 202. The camera microcomputer 101 obtains a control amount of the lens drive unit 202, that is, a drive amount (lens drive amount) of the lens group 202 based on the focus detection result by the focus detection circuit 107.

  The camera microcomputer 101 sends the calculated lens driving amount to the lens microcomputer 201. On the other hand, the position of the lens group 202 is detected by the encoder 204 and sent to the lens microcomputer 101 as lens position information.

  The lens microcomputer 201 controls the lens driving unit 203 according to the lens driving amount while referring to the lens position information, and moves the lens group 202 to the in-focus position. At the time of focus detection, focus detection information indicating the drive direction and drive speed of the lens group 202 is sent from the camera microcomputer 101 to the lens microcomputer 201. Then, the lens microcomputer 201 controls the lens driving unit 203 according to the focus detection information to drive the lens group 202 along the optical axis.

  The aperture 205 is for adjusting the amount of light incident on the camera body 100. The diaphragm control circuit 206 controls driving of the diaphragm 205 under the control of the lens microcomputer 201. The diaphragm drive amount necessary to control the diaphragm 205 is sent from the camera microcomputer 101 to the lens microcomputer 201. The focal length of the lens group 202 may be a single focal point, or may be variable as in the zoom lens.

  FIG. 4 is a flowchart for explaining a photographing operation performed by the camera shown in FIG.

  When the photographing operation is started, first, the camera microcomputer 101 determines whether the photographing standby button 114 has been operated (step S101). If the photographing standby button 114 is not operated, that is, if the photographing standby button 114 is not pressed (NO in step S101), the camera microcomputer 101 stands by.

  On the other hand, when the shooting standby button 114 is operated (YES in step S101), the camera microcomputer 101 selects center-weighted average photometry (medium weight) as the photometry method (photometry method) at the time of the first exposure control ( Step S102). As described above, in the center-weighted average metering, weight is placed at the center of the screen to average the relatively wide range.

  Subsequently, the camera microcomputer 101 performs face detection in the image data by the face detection circuit 116 (step S103). Then, the camera microcomputer 101 specifies and stores the number of face areas, the position in the image data of each face area, the size thereof, the direction of the face, etc. according to the face area detection result detected by the face detection circuit 116. Do.

  Next, the camera microcomputer 101 performs exposure control as described later (step S104). Then, the camera microcomputer 101 determines whether the recording start button 115 has been operated (step S105). When the recording start button 115 is operated (YES in step S105), the camera microcomputer 101 determines whether or not recording is currently performed (step S106).

  If it is not currently recording (NO in step S106), the camera microcomputer 101 controls the camera to start recording (step S107). On the other hand, if recording is currently in progress (YES in step S106), the camera microcomputer 101 stops recording (step S108).

  After the process of step S107 or S108, the camera microcomputer 101 determines whether the shooting standby button 114 has been operated (step S109). When the photographing standby button 114 is operated (YES in the step S109), the camera microcomputer 101 ends the photographing.

  On the other hand, when the shooting button is not operated (NO in step S109), the camera microcomputer 101 returns to the process of step S103. If the recording start button 115 is not operated (NO in step S105), the camera microcomputer 101 proceeds to the process of step S109.

  FIG. 5 is a flowchart for explaining the exposure control shown in FIG.

  When exposure control is started, the camera microcomputer 101 refers to the face detection result by the face detection circuit 116 and determines whether the number of detected face areas is 1 or more (step S201). If the number of face areas detected is one or more, that is, if there is a face area in the image data (YES in step S201), the camera microcomputer 101 performs exposure control in the face areas detected by the face use determination circuit 117. It is determined whether there is a face area to be used, and prioritization is performed as described later (step S202).

  Subsequently, the camera microcomputer 101 determines whether the face area detection result is used in the present exposure control (step S203). If a face area detection result is not used in the current exposure control (NO in step S203), that is, a face to be newly used for exposure control in a state where the face area detection result is not used in the current exposure control When the area is detected, the camera microcomputer 101 performs fluctuation removal processing on the face use determination result as described later (step S204).

  Subsequently, the camera microcomputer 101 determines whether or not there is a face area to be used in new exposure control (AE) according to the face use determination result or the face use determination result after the fluctuation removal process (step S205). . If the face area detection result is used in the current exposure control (YES in step S203), the camera microcomputer 101 proceeds to the process of step S205.

  If there is a face area to be used in the new exposure control (YES in step S205), the camera microcomputer 101 sets the photometric method (photometric mode) as evaluation photometry (step S206). On the other hand, if there is no face area to be used in the new exposure control (NO in step S205), the camera microcomputer 101 selects center weighted average photometry as the photometric method (step S207).

  As a result, when exposure control is performed without using a face area, even if a face area is newly detected, if a face area detection result is not stably output, the face area is immediately used for exposure control. Exposure control will continue without being used. Here, center-weighted average metering is continuously used as the metering method.

  If no face area is detected in the image data (NO in step S201), the camera microcomputer 101 determines whether a face area detection result is used in the present exposure control (step S208). If the face area detection result is used in the current exposure control (YES in step S208), the camera microcomputer 101 fixes (locks) the exposure control value for a predetermined period of time, assuming that the person's face has disappeared (AE) (AE) Lock: step S209). That is, when the face area detection result is used in the current exposure control and the face area used for the exposure control disappears, the camera microcomputer 101 performs AE lock for a predetermined time.

  The predetermined time is, for example, 5 seconds, and in the AE lock, the update of the photometric result as the target value of the exposure control, that is, the subject brightness is stopped. The method of fixing the exposure is not particularly limited, and updating of the photometry result is continued, and control values used for exposure control, for example, TV (shutter speed), AV (aperture value), and ISO sensitivity It may be fixed.

  Subsequently, the camera microcomputer 101 selects center weighted average metering as the metering method (step S210). If the face area detection result is not used in the current exposure control (NO in step S208), the camera microcomputer 101 proceeds to the process of step S210.

  When the AE lock is performed in step S209, although the photometric method is switched from the evaluation photometry to the center-weighted average photometry, the exposure of the image does not change immediately. In addition, when the face area of the person is detected again during the AE lock period, and the exposure control can be used, the photometry method returns to the evaluation photometry again. As a result, the exposure of the image does not change.

  After the process of step S206, S207, or S210, the camera microcomputer 101 obtains a target luminance in exposure control using the determined photometric method (step S211). The target brightness is not updated during the AE lock.

  Subsequently, the camera microcomputer 101 determines the TV, AV, and ISO sensitivities, which are exposure control values, according to the target brightness (step S212). During the AE lock, the exposure control value is not updated. Then, the camera microcomputer 101 ends the exposure control, and proceeds to the process of step S105 shown in FIG.

  FIG. 6 is a flowchart for explaining the face use determination process shown in FIG.

  When the face use determination process is started, the camera microcomputer 101 detects the face area in the image data based on the feature points of the face of the person by the face detection circuit 116, and obtains the face area detection result. Then, the camera microcomputer 101 assigns an identification number (ID) to each face area based on the face area detection result, and stores the size, direction, and position (coordinates) as a list in a face list.

  FIG. 7 is a diagram for explaining the face list stored in the camera microcomputer 101 shown in FIG. 7A shows an example of the face list, and FIG. 7B shows the face list after sorting.

  As shown in FIG. 7A, the face area detected in the image data is assigned an ID, and for each face area, its size, direction, and coordinates indicating the center position of the face area in the image are defined. It is done.

  The camera microcomputer 101 rearranges the face areas in the order of face size in the face list shown in FIG. 7A (step S301). Then, the camera microcomputer 101 checks the direction of the face area, and excludes the face area other than the face area facing the front direction or the oblique direction. That is, here, the camera microcomputer 101 excludes the face area facing sideways and backward (step S302).

  Note that, for example, the camera microcomputer 101 excludes a face area in which the direction of the face area is not within the range of 45 degrees from the front direction. In this manner, by excluding the sideways and backward face regions, it is possible to prevent the exposure control from being influenced by, for example, the color of the hair at the time of exposure control.

  When the face list shown in FIG. 7A is rearranged in this way, for example, the rearranged face list shown in FIG. 7B is obtained. In the rearranged face list, ID, orientation, and coordinates are associated with the order. Note that, in FIG. 7B, the face area in which “absent” is inserted in the ID column is the excluded face area.

  Subsequently, the camera microcomputer 101 selects the face area (selection detection result) having the highest priority from the rearranged face list based on the selection condition. That is, the camera microcomputer 101 outputs the direction and the coordinates (face use determination result) related to the face area with the highest priority in the rearranged face list (step S303), and ends the face use determination process. Then, the camera microcomputer 101 proceeds to the process of step S203 shown in FIG.

  In exposure control, the face area of the coordinates output in step S303 is used. Although the face area in the range of 45 degrees left and right from the front direction is used for the face direction, the face use determination result may not be stable depending on the condition of the subject in consideration of the error. Therefore, the fluctuation removal process is performed as follows.

  FIG. 8 is a flowchart for explaining the fluctuation removal process shown in FIG. When a plurality of face areas are detected, the fluctuation removal process is performed on each face area.

  When the fluctuation removal process is started, the camera microcomputer 101 compares the current face use determination result Fn with the previous face use determination result F (n-1) to determine whether they are the same (step S401). . If Fn = F (n-1) (YES in step S401), the camera microcomputer 101 adds 1 to a variable count which is a counter for determining the number of repetitions (step S402). On the other hand, if Fn = F (n-1) (NO in step S401), the camera microcomputer 101 clears the variable count to zero (step S403).

  After the process of step S402 or S403, the camera microcomputer 101 determines whether or not the variable count is equal to or more than a predetermined count value, for example, five or more (step S404). If the variable count is 5 or more (YES in step S404), the camera microcomputer 101 uses the latest face use determination result Fn as the fluctuation removal result Fout for the face use determination result (step S405). Then, the camera microcomputer 101 ends the fluctuation removal process, and proceeds to the process of step S205 shown in FIG.

  On the other hand, if the variable count is less than 5 (NO in step S404), the camera microcomputer 101 ends the fluctuation removal process and proceeds to the process of step S205 shown in FIG.

  FIG. 9 is a diagram for explaining the fluctuation removing operation performed by the camera shown in FIG.

  Now, it is assumed that the face area is not detected five consecutive times after the face area is detected twice continuously. In this case, the camera determines that there is no face area if the face area not used for exposure control continues to be detected four times. That is, after referring to the face area determination result a plurality of times, the camera switches the face area used in the exposure control. As a result, the exposure of the image is not sensitive to the fluctuation of the face area determination result.

  On the other hand, even when the face of the person is occluded due to the crossing of the object, the coordinates of the face relating to the occluded person in the exposure control for a while are used. Therefore, as described above, when the face area used for the exposure control disappears, the fluctuation removal process shown in step S204 of FIG. 5 is not performed.

  As a result, when there is another face area to which exposure control shifts when an object crosses, exposure control is promptly performed by the face area. Then, if there is no face area separately, the exposure for a predetermined time is fixed (AE lock), and after the face area of the person is not blocked, it is possible to return to the proper exposure control again.

  As described above, in the embodiment of the present invention, when exposure control is performed, fluctuation removal processing is performed when a face area newly appears, and fluctuation is performed when the face area used for exposure control disappears. Another face area is used for exposure control without performing removal processing. By this, it is possible to suppress the influence on the exposure of the image due to the false detection of the face area or the fluctuation of the face area detection result in the vicinity of the limit of the detection capability.

  Furthermore, in the embodiment of the present invention, when the face area used for the exposure control disappears and there is no separate face area, the exposure for a predetermined period is fixed without performing the fluctuation removal process. . By this, it is possible to remove the influence on the exposure of the image due to the false detection of the face area or the fluctuation of the face area detection result in the vicinity of the limit of the detection ability. Furthermore, the influence on the exposure by the object crossing the person can also be suppressed.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, The various form of the range which does not deviate from the summary of this invention is also included in this invention .

  For example, the control method may be performed by the exposure control apparatus as the control method of the above-described embodiment. In addition, a program provided with the functions of the above-described embodiment may be executed by a computer provided in the exposure control apparatus. The program is recorded on, for example, a computer readable recording medium.

Other Embodiments
The present invention supplies a program that implements one or more functions of the above-described embodiments to a system or apparatus via a network or storage medium, and one or more processors in a computer of the system or apparatus read and execute the program. Can also be realized. It can also be implemented by a circuit (eg, an ASIC) that implements one or more functions.

100 Camera body 101 Camera microcomputer (CCPU)
102 image sensor 106 photometry circuit (AE)
111 signal processing circuit 116 face detection circuit 117 face use determination circuit 200 lens unit 201 lens microcomputer (LPU)
206 Aperture control circuit

Claims (9)

Detection means for detecting a face area from an image obtained by imaging a subject;
Exposure control means for performing exposure control based on a result of photometry by a first photometry method of performing photometry by weighting the face area or a second photometry method different from the first photometry method;
In the first photometry method, when one or more face areas are detected by the detection unit, the face areas satisfying a predetermined condition are weighted to perform photometry.
The exposure control means performs the predetermined condition in a predetermined period after the face area satisfying the predetermined condition is not detected while the exposure control is performed by the first photometric method. If a new face area satisfying the condition is detected, the newly detected face area is weighted and exposure control is performed again using the first photometric method, and the detection means is performed in the predetermined period. An exposure control apparatus characterized by performing exposure control using said 2nd photometry method, when not detecting a new face field which fulfills said predetermined conditions.   The second photometry method is executed when the face area not satisfying the predetermined condition is not detected by the detection unit, and the center of the image is weighted to perform photometry. Exposure control device.   When changing from the first light measurement method to the second light measurement method, the exposure control means maintains an exposure based on a result of light measurement by the first light measurement method before the change during the predetermined period. The exposure control apparatus according to claim 1 or 2, wherein exposure control is performed using a second photometric method.   The predetermined condition is a condition for selecting a face area with high priority based on at least one of the size, position, and orientation of the face area. An exposure control device according to any one of the preceding claims.   The exposure control means first performs exposure control based on the photometric result according to the second photometry method after the photographing operation of the subject is started, and then the face area satisfying the predetermined condition is detected by the detection means. The exposure control apparatus according to any one of claims 1 to 4, wherein, when it is detected, exposure control is performed based on a photometric result according to the first photometric method.   The exposure control means adjusts the brightness of the moving image by performing exposure control based on the photometric result according to the first photometric method or the second photometric method when acquiring the moving image. The exposure control apparatus according to any one of claims 1 to 5.   The said exposure control apparatus is an imaging device provided with the imaging means, The exposure control apparatus of any one of the Claims 1 thru | or 5 characterized by the above-mentioned. Detecting a face area from an image obtained by imaging an object;
An exposure control step of performing exposure control on the basis of a photometry result obtained by weighting the face area and performing photometry, or a second photometry result different from the first photometry;
In the first photometry, when one or more face areas are detected by the detection step, photometry is performed in which the face areas that satisfy a predetermined condition are weighted.
In the exposure control step, when performing the exposure control based on the first photometry, a new period satisfying the predetermined condition is satisfied in a predetermined period after the face area satisfying the predetermined condition is not detected. When a face area is detected, the newly detected face area is weighted to perform exposure control based on the first photometry, and a new face area satisfying the predetermined condition in the predetermined period. Is not detected, exposure control based on the second photometry is performed.   A computer readable program for causing a computer to execute the exposure control method according to claim 8.