JP6335497B2 - Imaging device, control method thereof, and control program - Google Patents

Description

  The present invention relates to an imaging apparatus, a control method thereof, and a control program, and more particularly to control of a light emitting device such as a strobe device.

  In general, an imaging device including a light emitting device such as a strobe is known. There is an imaging apparatus that determines whether or not a shooting scene is a shooting scene having an effect of light emission such as backlight or night scene, and emits light according to the determination result.

  Further, in the imaging device, when the distance of the subject in the shooting scene is obtained and it is determined that the subject distance is closer than a predetermined distance, the light emitted from the light reaches the subject and emits light. is there.

  For example, there is an imaging apparatus that projects a predetermined amount of illumination light before shooting, and controls (first control) the main light emission amount at the time of shooting according to the reflected light. The imaging apparatus further includes a second control for controlling the main light emission amount by determining the timing for stopping the main light emission based on the reflected light by the main light emission (see Patent Document 1). Here, it is determined whether to use the first control or the second control according to the subject distance. When the reliability of the subject distance is low, the second control is used.

JP 2007-310026 A

  By the way, in the imaging device described in Patent Document 1, the light emission effect is small. For example, even when shooting a landscape at a long distance, light emission is performed by the first control or the second control. . In other words, light is emitted even in a state where light emission is unnecessary, and power sources such as batteries are inevitably consumed.

  As a result of light emission as described above, the number of times of charging is increased in the light emitting device, and the charging time for enabling light emission accordingly increases. For this reason, it is necessary to wait until the light emitting device is charged when shooting with light emission by the light emitting device, and a time lag occurs between charging and shooting.

  Considering such a time lag between charging and shooting and a decrease in the remaining battery level of the light emitting device due to light emission, it may be desirable not to emit light in a shooting scene with a small light emission effect.

  Accordingly, an object of the present invention is to provide an imaging apparatus that determines whether or not to emit light according to a shooting scene and emits light only in a shooting scene that has a light emission effect, a control method thereof, and a control program. is there.

In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus that shoots a subject by causing a light emitting unit to emit light according to a shooting scene, and the shooting scene corresponds to a shooting condition in a current shooting scene. First determination means for determining whether or not a light emission scene is to be emitted and obtaining a first determination result, subject distance indicating a distance to the subject in the current shooting scene, and light emission of the light emitting unit a second determination means for obtaining a second determination result the subject in accordance with the effective distance of light to determine whether or not a position a short distance of light reaches from the light emitting unit, the object distance Third determination means for determining whether or not the reliability has a predetermined reliability and obtaining a third determination result ; the first determination result ; the second determination result; and the third determination result the light emitting unit in accordance with the determination results It possesses a setting means for setting whether to perform photographing by light, wherein the setting means, have a reliability reliability of the object distance is the predetermined by the third determination results If it is determined that there is not, the setting is made such that shooting is performed without causing the light emitting unit to emit light regardless of the first determination result .

The control method according to the present invention is a control method of an imaging apparatus that shoots a subject by causing a light emitting unit to emit light according to a shooting scene, and the light emission that the shooting scene should emit according to shooting conditions in the current shooting scene. A first determination step of determining whether or not a scene is obtained and obtaining a first determination result; a subject distance indicating a distance to the subject in a current shooting scene; and an effective distance of light by light emission of the light emitting unit; A second determination step of determining whether or not the subject is located at a short distance where the light from the light emitting unit reaches, and obtaining a second determination result, and the reliability of the subject distance is predetermined. A third determination step for determining whether or not the obtained reliability is obtained and obtaining a third determination result, and according to the first determination result , the second determination result, and the third determination result The light emitting unit emits light Possess a setting step for setting whether to perform photographing, a, in the setting step, determines that the reliability of the subject distance does not have said predetermined reliability by the third determination results Then, it is set that shooting is performed without causing the light emitting unit to emit light regardless of the first determination result .

A control program according to the present invention is a control program used in an imaging device that shoots a subject by causing a light emitting unit to emit light according to a shooting scene, and the computer provided in the imaging device stores a shooting condition in a current shooting scene. A first determination step of determining whether or not the shooting scene is a light-emitting scene to emit light and obtaining a first determination result, and a subject distance indicating a distance to the subject in the current shooting scene A second determination result obtained by determining whether or not the subject is located at a short distance where the light from the light-emitting unit reaches according to the effective distance of the light emitted by the light-emitting unit and the second determination result steps and, a third determination step of reliability is obtained a third determination result by determining whether it has a predetermined degree of reliability of the object distance, the first determination result, the first The determination result and a setting step of setting whether to perform imaging by emitting the light emitting portion in response to the third determination results, to the execution, by the setting step, the by the third determination results When the reliability of the subject distance is determined to the do not have a predetermined confidence level, that you set and performs imaging the light emitting portion regardless of the first determination result without emission Features.

According to the present invention, it is possible only to emit light in a photographic scene is determined whether to perform the light emission has the effect of light according to the shooting scene.

It is a block diagram which shows the structure about an example of the imaging device by embodiment of this invention. 2 is a flowchart for explaining strobe light emission control performed in accordance with a determination result of whether or not a shooting scene has a strobe light emission effect in the camera shown in FIG. 1. 2A and 2B are diagrams for explaining calculation of luminance values performed by the camera illustrated in FIG. 1, in which FIG. 1A illustrates an example of an image, and FIG. 2B illustrates an example of a subject area in the image illustrated in FIG. (C) is a figure which shows a state when a to-be-photographed object area | region is not detected in the image shown to (a). 3 is a flowchart for explaining an example of a shooting scene determination process shown in FIG. 2. 3 is a flowchart for explaining calculation of a subject distance shown in FIG. 2. 3 is a flowchart for explaining strobe light emission determination processing shown in FIG. 2.

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

<Configuration of imaging device>
FIG. 1 is a block diagram showing the configuration of an example of an imaging apparatus according to an 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 photographing lens 101. An aperture / shutter 102, a focus lens 104, and an image sensor 106 are sequentially arranged after the photographing lens 101.

  The photographing lens 101 includes a zoom mechanism, and the diaphragm and shutter 102 are controlled by the AE processing unit 103, and the incident light amount of incident light (that is, an optical image) that is reflected from the subject and the charge accumulation in the image sensor 106. Adjust the time.

  The AE processing unit 103 controls the aperture and the shutter 102 based on a so-called P diagram showing the relationship between the aperture value, the shutter speed, and the sensitivity. Further, although no control line is shown, the AE processing unit 103 controls an A / D conversion unit 107 described later according to the P diagram.

  The focus lens 104 focuses on the light receiving surface of the image sensor 106 under the control of the AF processing unit 105 and forms an optical image on the image sensor 106. The image sensor 106 is a CCD or CMOS image sensor, for example, and outputs an electrical signal (analog signal) corresponding to the optical image formed on the light receiving surface to the A / D converter 107.

  The A / D conversion unit 107 converts an analog signal into a digital signal by A / D conversion. The A / D converter 107 includes a CDS (correlated double sampling) circuit that removes noise from the analog signal, and a nonlinear amplifier circuit that nonlinearly amplifies the analog signal before performing A / D conversion. doing.

  As illustrated, the camera includes an image processing unit 108, a format conversion unit 109, and a DRAM 110. The image processing unit 108 performs resize processing such as predetermined pixel interpolation and image reduction and color conversion processing on the digital signal output from the A / D conversion unit 107 and outputs image data. Further, the image processing unit 108 performs subject detection for detecting a specific region such as a human face region in the image data.

  The format conversion unit 109 converts the format of the image data that is the output of the image processing unit 108 in order to store the image data in the DRAM 110. The DRAM 110 is, for example, a high-speed built-in memory, and is used as a high-speed buffer for temporarily storing image data and as a working memory for compressing / decompressing image data.

  Further, the camera includes an image recording unit 111, a system control unit 112, a VRAM 113, a display unit 114, an operation unit 115, a main switch (main SW) 118, a first switch (SW1) 119, and a second switch (SW2). 120.

  The image recording unit 111 includes a recording medium such as a memory card for recording image data (still image or moving image) obtained as a result of photographing, and an interface thereof. The system control unit 112 includes, for example, a CPU, a ROM, and a RAM. The CPU expands and executes a program stored in the ROM in a RAM work area.

  As a result, the CPU controls the operation of the entire camera. In addition, the CPU determines in which imaging drive mode of the plurality of imaging drive modes the drive of the image sensor 106 is controlled.

  The VRAM 113 is a memory for image display, and the display unit 114 is, for example, an LCD. The display unit 114 displays an image, a display for assisting operations, and a camera state. At the time of shooting, a shooting screen and a distance measurement area are displayed.

  If the system control unit 112 determines that light emission (hereinafter referred to as strobe light emission) is necessary as described later, the system control unit 112 instructs the EF processing unit 116 to turn on the light emission unit (strobe unit). When the EF processing unit 116 receives a strobe on instruction, the EF processing unit 116 controls the strobe unit 117 so that the strobe unit 117 emits light during photographing.

  The user can operate the camera by operating the operation unit 115. The operation unit 115 includes menu switches for performing various settings such as exposure correction, aperture value setting, and image playback setting. Further, the operation unit 115 includes a zoom lever for instructing a zoom operation of the photographing lens 101, an operation mode switching switch for switching operation modes such as a photographing mode and a reproduction mode.

  The main switch 118 is a switch for turning on the camera. The first switch 119 is a switch for performing shooting preparation operations such as AE processing and AF processing, and the second switch 120 is a shooting instruction to the system control unit 112 after operating the first switch 119. It is a switch for performing.

<Operation of imaging device>
Here, in the camera shown in FIG. 1, a method for determining whether or not the shooting scene is a shooting scene effective with strobe light emission and performing strobe light emission only when strobe light emission is effective will be described.

  FIG. 2 is a flowchart for explaining strobe light emission control performed in accordance with the determination result of whether or not the camera scene shown in FIG. 1 is a shooting scene having a strobe light emission effect. Note that the processing according to the illustrated flowchart is performed under the control of the system control unit 112.

  When the camera is turned on by operating the main switch 118, the image processing unit 108 periodically performs AE processing to display an image with appropriate exposure on the display unit 114 under the control of the system control unit 112. (Step S201).

  In the AE process, the image processing unit 108 first calculates a luminance value of the entire image in image data obtained by performing exposure at a predetermined aperture value, shutter speed, and ISO sensitivity. Then, the system control unit 112 changes the aperture value, shutter speed, and ISO sensitivity so that the brightness value approaches a predetermined brightness value.

  FIG. 3 is a diagram for explaining calculation of luminance values performed by the camera shown in FIG. FIG. 3A is a diagram illustrating an example of an image, and FIG. 3B is a diagram illustrating an example of a subject area in the image illustrated in FIG. FIG. 3C is a diagram illustrating a state where a subject area is not detected in the image illustrated in FIG.

  In the image shown in FIG. 3A, when calculating the luminance value of the entire image, the image processing unit 108 divides the entire image (or part of the image) into a plurality of regions, here, M × N blocks. (Each of M and N is an integer of 2 or more). Then, the image processing unit 108 obtains the luminance value Y (m, n) (m = 0 to M−1, n = 0 to N−1) of each block according to the exposure.

  Next, the image processing unit 108 calculates the luminance value Y_All of the entire image according to the formula (1) using the photometric weight W (m, n).

Y_All = (ΣY (m, n) × W (m, n)) / ΣW (m, n) (1)
In Equation (1), for Σ, the sum of m = 0 to M−1 and n = 0 to N−1 is calculated.

  Subsequently, the system control unit 112 changes the aperture value, the shutter speed, and the ISO sensitivity so that the luminance value Y_All approaches the predetermined luminance value Y_Ref. Here, for example, the photometric weight W (m, n) is set to a larger value as it approaches the center of the screen.

  Referring to FIG. 2 again, the system control unit 112 determines whether or not the user has operated the SW1, that is, the first switch 119 (step S202). If the first switch 119 is not operated (NO in step S202), the system control unit 112 returns to the process of step S201 and performs the AE process.

  If there is no need to display a through image on the display unit 114, such as a camera having an optical viewfinder (not shown), the process of step S201 (AE process) may not be performed. The process may be performed from step S202.

  On the other hand, when first switch 119 is operated (YES in step S202), system control unit 112 performs a shooting preparation operation. Here, the image processing unit 108 detects a subject (subject area) in the image data (that is, a through image here) under the control of the system control unit 112 (step S203). For example, the image processing unit 108 detects a human face area as a subject area.

  Note that the subject may be periodically detected before the first switch 119 is operated. In this case, the subject detection result when the first switch 119 is operated (that is, the subject is detected). , The latest subject detection result) is acquired.

  Next, the system control unit 112 determines what kind of shooting scene the shooting scene is as described later (step S204). In the illustrated example, the system control unit 112 determines whether the shooting scene belongs to a night scene, a backlight scene, or another scene. If the system control unit 112 determines that the shooting scene is a night scene or a backlight scene, it is assumed that the strobe light can be emitted.

  Subsequently, the system control unit 112 calculates the distance of the subject in the determined shooting scene and obtains distance information (step S205). When obtaining the distance information, the system control unit 112 obtains the subject distance according to the subject information indicating the subject region obtained by subject detection in step S203. Alternatively, the system control unit 112 may set the distance to an area focused by AF processing described later as the subject distance.

  As will be described later, the system control unit 112 calculates the strobe light effective distance and compares the strobe light effective distance with the subject distance. Then, the system control unit 112 determines whether the subject distance is a short distance or a long distance according to the comparison result. At this time, the system control unit 112 also determines whether or not the subject distance is reliable.

  Subsequently, the system control unit 112 determines whether or not to emit the strobe unit 117 based on the photographing scene determination result and the subject distance (step S206: strobe emission determination) as described later.

  After the strobe light emission determination, the system control unit 112 determines whether or not the user has operated SW2, that is, operated the second switch 120 (step S207). If second switch 120 is not operated (NO in step S207), system control unit 112 stands by.

  On the other hand, when second switch 120 is operated (YES in step S207), system control unit 112 controls the camera to execute shooting (step S208). Then, the system control unit 112 ends the photographing process.

  Note that the processing in steps S203 to S206 is periodically performed so that the strobe emission determination can be updated when the shooting scene changes between the operation of the first switch 119 and the operation of the second switch 120. You may make it perform. In addition, a scene change unit that determines whether or not a change has occurred in the camera or the shooting scene may be provided, and the processes in steps S203 to S206 may be performed again only when a scene change has occurred.

<Shooting scene discrimination>
FIG. 4 is a flowchart for explaining an example of the photographing scene determination process shown in FIG.

  Note that the processing according to the illustrated flowchart is performed under the control of the system control unit 112. Here, a case will be described in which it is determined whether a shooting scene belongs to any one of a night scene, a backlight scene, and other scenes.

  When the shooting scene determination process is started, under the control of the system control unit 112, the image processing unit 108 performs an AE process to obtain shooting conditions such as exposure in the current shooting scene (step S401). Here, for example, the AE process is performed in the same manner as in step S201. Then, the system control unit 112 obtains the aperture value, the shutter speed, and the ISO sensitivity at the time of photographing where the luminance value Y_All = predetermined luminance value Y_Ref of the entire image.

  Here, the exposure amount (a value based on the aperture value, ISO sensitivity, shutter speed, and the like) is obtained after the first switch 119 is operated, but the time from the user operation to photographing is shortened. Therefore, all or part of the result of AE processing of the through image may be taken over.

  Next, the system control unit 112 compares the shutter speed at the time of shooting with the shutter threshold value to determine whether the shutter speed is slower than the predetermined shutter threshold value (Th_Speed) (long time) ( Step S402). If the shutter speed at the time of shooting is slower than the shutter threshold (Th_Speed) (YES in step S402), system control unit 112 determines that the current shooting scene is a night scene (step S403).

  On the other hand, when the shutter speed at the time of shooting is faster than the shutter threshold (Th_Speed) or higher (shutter threshold or higher) (NO in step S402), the system control unit 112 determines whether the current shooting scene is a backlight scene or other scenes. It is determined whether it is.

  Here, first, the system control unit 112 determines whether or not a subject area has been detected in the process of step S203 described above (step S404). When the subject area is detected (YES in step S404), the system control unit 112 backlights the current shooting scene according to the luminance difference between the subject area and other areas other than the subject area as follows. It is determined whether it is a scene.

  Here, first, the system control unit 112 calculates the average luminance SubjectY of the area corresponding to the subject area (step S405). As described above, since the face area of the person is the subject area, the relationship among the subject area 301, the area 302 for calculating the average luminance (subject average luminance) SubjectY, and the other areas 303 is shown in FIG. It becomes a relationship.

  In FIG. 3B, the system control unit 112 applies the face area to the image of the M × N block and sets a block including the face area in each block of the M × N block as a block corresponding to the subject area. Then, the system control unit 112 calculates the average luminance SubjectY in an area to which a block corresponding to the subject area belongs (referred to as an average luminance calculation area).

  When calculating the average luminance SubjectY, the system control unit 112 obtains the average luminance SubjectY by averaging the luminance values Y (m, n) for each block in the average luminance calculation area. Note that the average luminance SubjectY may be obtained after increasing the weighting coefficient and multiplying the luminance value Y (m, n) by the weighting coefficient for a block having a larger ratio of the subject area to the block area.

  Next, the system control unit 112 calculates an average luminance (background average luminance) BackGroundY other than the subject region (step S406). Here, the system control unit 112 calculates the average luminance of the M × N blocks that are not used for calculating the subject average luminance SubjectY in step S405.

  Similarly to the AE process, the background average luminance BackGroundY may be calculated by the following equation (2) using the photometric weight W (m, n).

BackGroundY = (ΣY (m, n) × W (m, n)) / ΣW (m, n) (2)
For Σ, the sum of blocks other than the subject area is calculated from m = 0 to M−1 and n = 0 to N−1.

  Subsequently, the system control unit 112 obtains a ratio (SubjectY / BackGroundY) between the subject average luminance SubjectY and the background average luminance BackGroundY. Then, the system control unit 112 determines whether or not the ratio is smaller than a predetermined ratio threshold value Th_Y (step S407). That is, the system control unit 112 determines whether the subject area is darker than the predetermined darkness with respect to the background area using the following equation (3).

SubjectY / BackGroundY <Th_Y (3)
If the subject area is not detected (NO in step S404), the system control unit 112 determines whether the scene is a backlight scene based on the luminance difference between the image center (that is, the screen center) and the surrounding area. . When the subject region is not detected, the relationship between the screen center 304 (the region within the screen center Center%) and the peripheral region 305 is the relationship shown in FIG.

  In FIG. 3C, the system control unit 112 averages the luminance values of the blocks belonging to the screen center portion 304 to obtain the average luminance, and sets the average luminance as the screen center luminance CenterY. Similarly to the AE process, the screen center average luminance CenterY may be calculated by the following formula (4) using the photometric weight W (m, n).

CenterY = (ΣY (m, n) × W (m, n)) / ΣW (m, n) (4)
For Σ, the sum of the blocks in the screen center 304 is calculated from m = 0 to M−1 and n = 0 to N−1.

  Next, the system control unit 112 calculates the average luminance (peripheral average luminance) PeripheryY in the peripheral region 305 outside the screen center portion 304 (step S409). In this case as well, the peripheral average luminance PeripheryY may be calculated using the photometric weight W (m, n) in the same manner.

  Subsequently, the system control unit 112 obtains a ratio (CenterY / PeripheryY) between the screen center CenterY and the peripheral average luminance PeripheryY. Then, the system control unit 112 determines whether or not the ratio is smaller than a predetermined ratio threshold value Th_Y (step S410). That is, the system control unit 112 determines whether or not the screen center part 304 is darker than the predetermined darkness with respect to the peripheral area 305 using the following equation (5).

CenterY / PeripheryY <Th_Y (5)
If SubjectY / BackGroundY <Th_Y (YES in step S407) or CenterY / PeripheryY <Th_Y (YES in step S410), the system control unit 112 determines that the current shooting scene is a backlight scene ( Step S411).

  On the other hand, if SubjectY / BackGroundY ≧ Th_Y (NO in step S407) or CenterY / PeripheryY ≧ Th_Y (NO in step S410), system control unit 112 determines that the current shooting scene is another scene. Determination is made (step S412).

  Subsequent to step S403, step S411, or step S412, the system control unit 112 determines whether or not the current shooting scene is a shooting scene suitable for strobe light emission. Here, the system control unit 112 determines whether or not the current shooting scene is a night scene or a backlight scene (step S413).

  If the current shooting scene is a night scene or a backlight scene (YES in step S413), the system control unit 112 determines that the current shooting scene is a strobe flashing scene (first determination result) capable of flash emission. (Step S414). Then, the system control unit 112 ends the shooting scene determination process, and proceeds to the process of step S205 shown in FIG.

  On the other hand, if the current shooting scene is not a night view scene or a backlight scene (NO in step S413), the system control unit 112 determines that the current shooting scene is a strobe non-flashing scene (first determination result) incapable of flashing. Determination is made (step S415). Then, the system control unit 112 ends the shooting scene determination process, and proceeds to the process of step S205 shown in FIG.

  By the way, when taking a picture, in general, as the shutter speed becomes slower in a night scene or the like, camera shake and subject shake tend to occur. On the other hand, blurring is suppressed by increasing the shutter speed (that is, by using a high-speed shutter), and the exposure amount reduced by the high-speed shutter is compensated by strobe light emission. Therefore, in the shooting scene determination process, when the shutter speed is slower than the predetermined shutter threshold Th_Speed, it is regarded as a night scene and the flash light emission is enabled.

  On the other hand, in a backlight scene, the subject is relatively dark and the background is bright. In this case, if the exposure conditions are changed, such as opening the aperture, using a low-speed shutter, or increasing the sensitivity, the background may become brighter and the gradation may deteriorate, such as overexposure.

  In order to suppress the background whiteout and to shoot the subject brightly, it is effective to emit the strobe light without changing the exposure condition at the time of shooting. Therefore, in the shooting scene determination process, strobe light emission is possible even in a backlight scene.

  When performing strobe light emission, the aperture, shutter speed, or ISO sensitivity at the time of shooting obtained in step S401 described above may be changed. For example, in order to suppress blurring, the shutter speed may be set to a shorter time than when the strobe is not emitting light.

  As described above, in the shooting scene determination process, it is determined whether the current shooting scene is a night scene, a backlight scene, or another scene.

<Distance information calculation>
FIG. 5 is a flowchart for explaining calculation of the subject distance (distance information) shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the system control unit 112.

  When calculation of the distance information is started, the system control unit 112 performs AF processing (step S501). In the AF process, for example, the system control unit 112 obtains the position of the focus lens 104 at which the high frequency component of the luminance signal is maximum in the image data as the focus position.

  Here, the system control unit 112 drives the focus lens 104 along the optical axis of the photographing lens 101 over the entire distance measurement range, and calculates the AF evaluation value (corresponding to the high frequency component of the luminance signal). Auto focus evaluation value) is stored. Then, the system control unit 112 sets the position of the focus lens 104 corresponding to the maximum AF evaluation value among the stored AF evaluation values as the focus position. That is, the system control unit 112 scans the focus lens 104 to obtain the in-focus position.

  Subsequently, the system control unit 112 determines whether or not a subject is detected in step S203 (step S502). When the subject is detected (YES in step S502), system control unit 112 calculates subject distance Subject Distance based on the subject detection result (step S503).

  Here, for example, the vertical distance Height of the through image (image data), the length Face_Size of one side of the rectangular area, and the focal length F at the time of shooting are used to calculate the subject distance Subject Distance by the following equation (6). Is done.

  Note that the rectangular area is one rectangular area (a specific area including the face area) of the through image, and the coordinates of the center are (X, Y). Then, the subject distance is calculated according to the specific area that is the area of the specific region.

SubjectDistance = F × Face_Size ÷ Height × Coefficient
(6)
Here, the coefficient of Expression (6) is set in advance so that the subject distance Subject Distance, the length of one side of the face area, and the focal length are approximated when an actual person is photographed.

  Next, the system control unit 112 calculates an estimated subject distance estimated based on the shooting conditions (step S504). In addition to the case where the subject is an actual person, the subject may be a small doll or a very large humanoid image. Since the subject distance SubjectDistance obtained in step S503 does not limit the size of the subject (specific area of the specific area), the subject distance SubjectDistance may differ greatly from the actual distance.

  Therefore, the system control unit 112 estimates the estimated subject distance Estimation Distance according to the shooting condition, for example, the focal length F at the time of shooting. When obtaining the estimated subject distance Estimation Distance, the area occupied by the specific region in the through image is estimated as the estimated area according to the focal distance, and the estimated subject distance Estimation Distance is obtained according to the estimated area. Then, the system control unit 112 compares the estimated subject distance Estimation Distance with the subject distance Subject Distance.

  The estimated subject distance Estimation Distance may be stored in advance in the system control unit 112 in association with the focal length F as statistical data. When generating statistical data, for example, when photographing a subject, the subject distance is measured at each of a plurality of focal lengths, and the measured data obtained by the actual measurement is tabulated to obtain statistical data.

  Furthermore, a calculation formula for deriving the estimated subject distance Estimation Distance from the focal length F may be obtained from statistical data and used.

  Subsequently, the system control unit 112 evaluates the reliability of the subject distance Subject Distance. Here, the system control unit 112 determines whether or not the absolute value difference between the subject distance Subject Distance and the estimated subject distance Estimation Distance is less than a predetermined difference threshold Th_Dist (step S505).

  If the subject is not detected (NO in step S502), the system control unit 112 subjects the subject distance SubjectDistance according to the result of the AF process (that is, the position of the focus lens 104) regardless of the AF evaluation value obtained by the AF process. Is obtained (step S506).

  For example, the system control unit 112 stores in advance a table indicating the subject distance Subject Distance corresponding to the relationship between the focal length and the position of the focus lens 104. Then, the system control unit 112 obtains the subject distance Subject Distance by referring to the table according to the focal length and the position of the focus lens 104.

  Next, the system control unit 112 performs reliability determination processing of AF distance information (that is, subject distance) (step S507). Then, the system control unit 112 determines whether the reliability (also referred to as reliability) of the AF distance information is high according to the result of the reliability determination process (step S508).

  When the difference difference between the maximum value and the minimum value of the AF evaluation value is equal to or smaller than a predetermined difference threshold value or the gradient around the maximum value of the AF evaluation value is equal to or smaller than the predetermined threshold value, the maximum value of the AF evaluation value is set. It is unlikely that the subject is present at the corresponding position. In this case, the system control unit 112 assumes that the reliability of the AF distance information is low.

  Further, when the accuracy of the operation of the focus lens 104 is low, when the S / N ratio is deteriorated due to low illuminance and low contrast, the AF distance information varies. Due to this variation, it may not be possible to distinguish between infinity and finite distance.

  Therefore, when the subject distance Subject Distance is larger (far) than a predetermined distance range (effective distance range) set according to a predetermined AF variation range, the system control unit 112 can distinguish between infinity and a finite distance. Assume that the reliability of the AF evaluation value is low.

  If the absolute value difference between the subject distance Subject Distance and the estimated subject distance Estimation Distance is less than a predetermined difference threshold Th_Dist (YES in step S505) or if the AF distance information is highly reliable (YES in step S508), system control The unit 112 is assumed to have high reliability of the subject distance Subject Distance (step S509).

  On the other hand, if the absolute value difference between the subject distance Subject Distance and the estimated subject distance Estimation Distance is greater than or equal to a predetermined difference threshold Th_Dist (NO in step S505) or the reliability of the AF distance information is low (NO in step S508), The system control unit 112 assumes that the subject distance Subject Distance has low reliability (step S510).

  Subsequent to step S509 or S510, the system control unit 112 obtains the strobe light effective distance (step S511). The strobe light effective distance is also referred to as a dimming interlocking range. Here, in calculating the strobe light effective distance StrobeDistance, the strobe guide number Gno, the aperture value Fno during shooting, and the ISO sensitivity Gain are used. The calculated strobe light effective distance StrobeDistance represents a distance (range) at which the effect of the strobe light emission can be sufficiently obtained. Then, the system control unit 112 calculates the strobe light effective distance StrobeDistance according to Expression (7) that is a relational expression of known guide numbers.

StrobeDistance = Gno × Sqrt (Gain / 100) / Fno
(7)
Subsequently, the system control unit 112 determines whether or not the strobe light effective distance StrobeDistance is larger than the subject distance SubjectDistance (step S512). If the effective strobe light distance StrobeDistance is larger than the subject distance SubjectDistance (YES in step S512), that is, if it is determined that the effect of light emission from the strobe light is sufficiently obtained, the system control unit 112 sets the subject distance SubjectDistance to a short distance ( (Second determination result) (step S513). Then, the system control unit 112 ends the distance information calculation process.

  On the other hand, if the strobe light reaching distance StrobeDistance is equal to or shorter than the subject distance SubjectDistance (NO in step S512), that is, if it is determined that the effect of the strobe light emission is not sufficiently obtained, the system control unit 112 sets the subject distance SubjectDistance to It is assumed that it is a long distance (second determination result) (step S514). Then, the system control unit 112 ends the distance information calculation process.

<Strobe flash judgment>
FIG. 6 is a flowchart for explaining the strobe emission determination process shown in FIG. Note that the processing according to the illustrated flowchart is performed under the control of the system control unit 112.

  When the flash emission determination process is started, the system control unit 112 determines whether or not the current shooting scene is a shooting scene capable of flash emission (flash emission scene) (step S601). That is, the system control unit 112 confirms whether or not the current shooting scene is a night scene or a backlight scene based on the determination result by the shooting scene determination process described with reference to FIG.

  If the current shooting scene is a strobe lighting scene (YES in step S601), system control unit 112 determines whether or not the subject distance calculated as described above is highly reliable (step S602). .

  If the subject distance has high reliability (YES in step S602), the system control unit 112 determines whether or not the subject distance calculated as described above is a short distance (step S603). . That is, the system control unit 112 determines whether or not the subject is located at a distance at which the effect of the strobe light emission is sufficiently obtained.

  If the subject distance is a short distance (YES in step S603), system control unit 112 sets strobe light emission in EF processing unit 116 (step S604). In other words, when the current shooting scene is a night scene or a backlight scene and the subject distance is a high reliability and a short distance, the system control unit 112 sets the flash photography. Then, the system control unit 112 ends the strobe light emission determination process.

  On the other hand, if the subject distance is not a short distance (NO in step S603), the system control unit 112 sets the EF processing unit 116 to be non-flashing (step S605). That is, if the current shooting scene is neither a night scene nor a backlight scene, or if the subject distance is not highly reliable or not close, the system control unit 112 performs setting for flash non-flash shooting. Then, the system control unit 112 ends the strobe light emission determination process.

  If the current shooting scene is not a strobe lighting scene (NO in step S601), the system control unit 112 proceeds to the process of step S605. Similarly, if the subject distance is not highly reliable (NO in step S602), system control unit 112 proceeds to the process of step S605. If the subject distance is not a short distance (NO in step S603), that is, if the subject distance is a long distance, the system control unit 112 proceeds to the process of step S605.

  In the flowchart shown in FIG. 6, when the current shooting scene is a flash emission scene and the subject distance is high reliability, the flash emission is set if the subject distance is short, but the subject distance is In the case of low reliability, if the current shooting scene is a flash emission scene and the subject distance is a short distance, it may be determined that the flash emission. That is, if “YES” in the process of step S601, the process proceeds to step S603 regardless of the reliability of the subject distance.

  As described above, in the embodiment of the present invention, it is determined whether or not the current shooting scene is a shooting scene having an effect of the flash emission, and the flash emission is performed according to the determination result. It is possible to reliably prevent a time lag between charging and shooting in the flash device and a decrease in the remaining battery level of the flash device due to light emission.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to these embodiment, Various forms of the range which does not deviate from the summary of this invention are also contained in this invention. .

  For example, the function of the above embodiment may be used as a control method, and this control method may be executed by the imaging apparatus. Further, a program having the functions of the above-described embodiments may be used as a control program, and the control program may be executed by a computer included in the imaging apparatus. The control program is recorded on a computer-readable recording medium, for example.

  The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various recording media, and the computer (or CPU, MPU, etc.) of the system or apparatus reads the program. To be executed.

DESCRIPTION OF SYMBOLS 103 AE processing part 104 Focus lens 105 AF processing part 106 Image sensor 107 A / D conversion part 108 Image processing part 112 System control part 115 Operation part 116 EF processing part 117 Strobe part

Claims (11)

An imaging device that shoots a subject by causing a light emitting unit to emit light according to a shooting scene,
First determination means for determining whether or not the shooting scene is a light-emitting scene that should emit light according to the shooting conditions in the current shooting scene, and obtaining a first determination result;
Whether or not the subject is located at a short distance where the light from the light emitting unit reaches according to the subject distance indicating the distance to the subject in the current shooting scene and the effective distance of the light emitted by the light emitting unit. Second determination means for determining and obtaining a second determination result;
Third determination means for determining whether or not the reliability of the subject distance has a predetermined reliability and obtaining a third determination result;
Setting means for setting whether to perform shooting by emitting light from the light-emitting unit according to the first determination result , the second determination result, and the third determination result ;
I have a,
If it is determined by the third determination result that the reliability of the subject distance does not have the predetermined reliability, the setting unit causes the light emitting unit to be turned on regardless of the first determination result. An image pickup apparatus that is set to perform shooting without emitting light . The setting means determines that the reliability of the subject distance has the predetermined reliability based on the third determination result, and the current shooting scene is determined to be a light emission scene based on the first determination result. 2. The apparatus according to claim 1, wherein when it is determined that the subject is located at a short distance according to the second determination result, the light emitting unit is set to emit light and perform shooting. Imaging device. The first determination unit determines that the current shooting scene is the light emission scene when a shutter speed at the time of shooting, which is one of the shooting conditions, is slower than a predetermined shutter threshold value. The imaging apparatus according to claim 1 or 2 . When the shutter speed is equal to or higher than the shutter threshold, the first determination unit is configured to exclude an average luminance in a predetermined area set in a through image obtained in the current shooting scene and an area excluding the predetermined area. The imaging apparatus according to claim 3 , wherein the current shooting scene is determined to be the light emission scene when the ratio of the average brightness to the brightness is smaller than a predetermined ratio threshold. A calculation unit that detects a specific area in the through image obtained in the current shooting scene, determines the area of the specific area in the through image as a specific area, and calculates the subject distance according to the specific area; the imaging apparatus according to any one of claims 1 to 4, characterized in. The imaging apparatus according to claim 5 , wherein the specific area is a face area. Before shooting in the current shooting scene, the focus lens is driven and controlled along the optical axis to obtain an autofocus evaluation value, and the in-focus position of the focus lens is obtained according to the autofocus evaluation value. the imaging apparatus according to any one of claims 1-4, characterized in that it comprises a calculating means for obtaining the object distance based on the focus position. Said third judging means, wherein the focus lens is focused, imaging of claim 7 reliability of the object distance, wherein the benzalkonium be determined to be higher than the reliability said predetermined apparatus. Said third determination means, claim the subject distance to be in a predetermined effective distance range, reliability of the object distance, wherein the benzalkonium be determined to be higher than the reliability said predetermined 8. The imaging device according to 7 . A method for controlling an imaging apparatus that shoots a subject by causing a light emitting unit to emit light according to a shooting scene,
A first determination step of determining whether or not the shooting scene is a light-emitting scene that should emit light according to the shooting conditions in the current shooting scene, and obtaining a first determination result;
Whether or not the subject is located at a short distance where the light from the light emitting unit reaches according to the subject distance indicating the distance to the subject in the current shooting scene and the effective distance of the light emitted by the light emitting unit. A second determination step of determining and obtaining a second determination result;
A third determination step of determining whether or not the reliability of the subject distance has a predetermined reliability and obtaining a third determination result;
A setting step for setting whether to perform shooting by emitting light from the light-emitting unit according to the first determination result , the second determination result, and the third determination result ;
I have a,
In the setting step, when it is determined by the third determination result that the reliability of the subject distance does not have the predetermined reliability, the light emitting unit is turned on regardless of the first determination result. A control method, characterized in that setting is made when shooting is performed without light emission . A control program used in an imaging apparatus that shoots a subject by causing a light emitting unit to emit light according to a shooting scene,
In the computer provided in the imaging device,
A first determination step of determining whether or not the shooting scene is a light-emitting scene that should emit light according to the shooting conditions in the current shooting scene, and obtaining a first determination result;
Whether or not the subject is located at a short distance where the light from the light emitting unit reaches according to the subject distance indicating the distance to the subject in the current shooting scene and the effective distance of the light emitted by the light emitting unit. A second determination step of determining and obtaining a second determination result;
A third determination step of determining whether or not the reliability of the subject distance has a predetermined reliability and obtaining a third determination result;
A setting step for setting whether to perform shooting by emitting light from the light-emitting unit according to the first determination result , the second determination result, and the third determination result ;
Was executed,
In the setting step, when it is determined by the third determination result that the reliability of the subject distance does not have the predetermined reliability, the light emitting unit is turned on regardless of the first determination result. control program characterized that you set and perform photographing without light.

Images