JP2015040939A - Image-capturing device, control method therefor, and control program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the focusing accuracy of an image-capturing device using framing-assist zoom at the time of photographing a subject.SOLUTION: In performing focus adjustment in which when, while moving a zoom lens along the optical axis of an image-forming optical system and framing a subject to the photographing field angle of a photographic image, a state in which the subject is not detected is entered from a state in which the subject is detected, a focus lens is moved along the optical axis in accordance with image data corresponding to a partial region of the photographic image to adjust the focus, a system control unit 115 has the aforementioned partial region set for a first region as an AF frame by an AF gate 110.

Description

  The present invention relates to an imaging apparatus having a so-called framing assist zoom function, a control method thereof, and a control program, and more particularly, to a control method for improving focusing accuracy when a person is photographed.

  In general, in an imaging apparatus such as a digital camera, an optical zoom function that performs optical scaling by driving a zoom lens, and electronic scaling is performed by enlarging a part of an image area obtained as a result of imaging. Some have an electronic zoom function. When shooting at the telephoto end (telephoto side) using such a zoom function, the subject is often out of frame due to a slight change in the orientation of the imaging device or camera shake of the operator. .

  In order to prevent such a frame-out, that is, to capture the subject immediately when the subject is out of the frame, there is an imaging apparatus having a function called framing assist zoom (framing assist zoom) (see Patent Document 1). . Furthermore, there is an imaging apparatus having a so-called auto zoom function that detects a subject in an image and changes a zoom position according to the detection information.

  In addition, there is an imaging apparatus that zooms out the zoom position in the wide-angle direction when the subject reaches the limit position of the specific area on the screen (see Patent Document 2). In addition, there is an imaging device that zooms in on the zoom position in the telephoto direction when the subject is in the center of the screen (see Patent Document 3).

  On the other hand, in autofocus (hereinafter referred to as AF) control in an image pickup apparatus, the sharpness of an image is detected based on a video signal obtained according to a subject image in a predetermined area (hereinafter referred to as an AF frame) of the image pickup device. There is something. Here, the sharpness is used as an AF evaluation value, and the focus lens is driven and controlled at a focus lens position where the AF evaluation value is maximized (hereinafter also referred to as a focus position) to perform focus adjustment.

  In particular, there is known an imaging apparatus that detects a face area included in an image when a person is photographed as a main subject and performs AF control according to the detection result. For example, there is an imaging apparatus that performs AF control by setting an AF frame so as to include a detected face area (see Patent Document 4).

JP 2012-60595 A JP 61-39011 A JP-A-61-46921 JP 2006-227080 A

  By the way, when the AF control is performed by detecting the face area of the main subject as described above, the AF control is always performed by setting the AF frame following the detected face area. However, for example, when the main subject turns sideways, when the eyes are closed, or when another subject temporarily covers the main subject, the face of the main subject is continuously displayed. It becomes difficult to detect the region. That is, the face area is not always detected.

  For this reason, while the face area is detected, AF control is performed with the AF frame set to follow the detected face area, and when no face is detected, the previous face area is detected. In some cases, AF control is performed using the AF frame set in the above state.

  However, with the above method, when the main subject is moving, the face area does not always exist at the same position as the previous state, and the set AF frame can follow the actual position of the face area. Without being in focus as a result of AF control.

  In particular, when trying to prevent the main subject from being out of frame using the framing assist zoom described above, it is difficult to prevent the main subject from being out of frame unless the main subject can be continuously focused. End up.

  Accordingly, it is an object of the present invention to provide an imaging apparatus capable of improving the focusing accuracy in photographing an object, an control method thereof, and a control program in an imaging apparatus using a framing assist zoom.

  In order to achieve the above object, an imaging apparatus according to the present invention is an imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens, and the zoom lens is connected to the imaging optical system. A framing means for framing the subject at the shooting angle of view in the captured image by moving along the optical axis of the image, and the focus lens on the optical axis according to image data corresponding to a partial area in the captured image. A focus adjustment unit that moves along the focus, a subject detection unit that detects the subject in the captured image, and a state in which the subject is not detected from a state in which the subject is detected by the subject detection unit. When the framing by the framing means is being executed, the partial area is preliminarily recorded in the captured image. A setting unit configured to set as a frame region in a first area defined, and having a.

  A control method according to the present invention is a control method of an imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens, and the zoom lens is moved along an optical axis of the imaging optical system. A framing step of moving and framing the subject at the shooting angle of view in the captured image, and moving the focus lens along the optical axis according to image data corresponding to a part of the region of the captured image. A focus adjustment step for adjusting, a subject detection step for detecting the subject in the captured image, and a framing step when the subject is not detected from the state in which the subject is detected in the subject detection step. If the framing by And having a setting step of setting as a frame region in the first region is because, the.

  A control program according to the present invention is a control program used in an imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens, and the zoom lens is installed in a computer included in the imaging apparatus. A framing step of moving along the optical axis of the imaging optical system and framing the subject at the shooting angle of view in a captured image, and the focus lens according to image data corresponding to a partial area in the captured image A focus adjustment step of moving along the optical axis to adjust the focus, a subject detection step of detecting the subject in the captured image, and detecting the subject from a state in which the subject is detected in the subject detection step When the framing step is not performed, When ring is running, characterized in that to execute setting steps, the setting the partial region as a frame region in a first area defined in advance in the captured image.

  According to the present invention, if the framing is being executed when the subject is not detected from the state in which the subject is detected, the frame area (AF frame) set when performing the focus adjustment is captured. The first area is set in advance. As a result, even when framing is being performed, it is possible to improve the focusing accuracy when shooting the subject.

1 is a block diagram illustrating a configuration of an example of an imaging apparatus according to a first embodiment of the present invention. 4 is a flowchart for explaining an example of FA zoom performed by the camera shown in FIG. 1. 3 is a flowchart for explaining an example of AF control performed by the camera shown in FIG. 1. 4 is a flowchart for explaining an example of a normal AF sequence shown in FIG. 3. FIG. 6 is a diagram for explaining setting of a face frame according to the face area detected by the face detection unit shown in FIG. 1, (a) is a diagram showing an example of face frame setting according to the face detection result; (A) is a figure which shows the other example of the face frame setting according to a face detection result, (c) is a figure which shows an example of the face frame set to the center part of a view angle. 4 is a flowchart for explaining an example of an AF sequence for FA zoom shown in FIG. 3. It is a flowchart for demonstrating AF control performed with the camera by the 2nd Embodiment of this invention.

[First Embodiment]
FIG. 1 is a block diagram showing the configuration of an example of an imaging apparatus according to the first embodiment of the present invention.

<Overall configuration of imaging device>
The illustrated imaging apparatus is, for example, a digital camera (hereinafter simply referred to as a camera) and includes a system control unit 115. The system control unit 115 controls the entire camera and includes, for example, a CPU, a RAM, and a ROM. Then, the CPU uses the RAM as a work area according to a program recorded in advance in the ROM, and controls the operation of the camera.

  The taking lens unit (hereinafter simply referred to as a taking lens) 100 has a zoom function. The zoom lens control unit 101 drives and controls a zoom lens that changes the focal length under the control of the system control unit 115.

  The aperture / shutter controller 102 drives and controls an aperture and a shutter that adjust the amount of light under the control of the system controller 115. The focus lens control unit 103 drives and controls the focus lens under the control of the system control unit 115 to focus on the light receiving surface (also referred to as an imaging surface) of the image sensor 104.

  Although not shown, the zoom lens control unit 101, the aperture / shutter control unit 102, and the focus lens control unit 103 are optical elements such as a lens, mechanisms such as an aperture / shutter, and are necessary for driving them. Equipped with various devices. Various devices include an optical element and an actuator for driving the above mechanism, a circuit for controlling the actuator, a D / A converter, and the like.

  The image sensor 104 outputs an electrical signal (analog signal) corresponding to incident light (optical image). For example, the imaging element 104 is a CCD or CMOS image sensor, and includes a plurality of photoelectric conversion elements, and photoelectrically converts incident light to generate an imaging signal (image signal) that is an analog signal.

  The imaging processing unit 105 includes a CDS (correlated double sampling) circuit, a non-linear amplification circuit, and an A / D conversion unit. The CDS circuit removes noise in the imaging signal that is the output of the imaging element 104 by correlated double sampling. The nonlinear amplifier circuit performs signal amplification (gain control) on the imaging signal from which noise has been removed. The A / D converter converts the signal-amplified imaging signal into a digital signal (image data).

  Note that the imaging element 104 and the imaging processing unit 105 function as an imaging unit that obtains image data by imaging a subject.

  The image processing unit 106 performs predetermined image processing such as gamma correction and contour correction on the image data. Further, the image processing unit 106 performs white balance processing on the image data. The format conversion unit 107 converts the processed image data output from the image processing unit 106 into a format suitable for recording and display.

  A DRAM (random access memory) 108 is a high-speed built-in memory, and is used as a high-speed buffer that temporarily stores image data that has undergone format conversion (converted image data). The DRAM 108 is also used as a working memory when compressing / decompressing the converted image data. The image recording unit 109 includes a recording medium such as a memory card and an interface, and the converted image data stored in the DRAM 108 is recorded in the image recording unit 109.

  The AF gate unit 110 outputs only a signal corresponding to a region (part of a captured image) used for automatic focus adjustment (AF) among all the pixels of the image sensor 104 with respect to the image data output from the imaging processing unit 105. This is selectively passed as area image data.

  In the following description, an area used for AF (AF signal acquisition area) is referred to as an AF frame. That is, the AF frame is an evaluation value frame for evaluating image data during AF.

  The AF processing unit 112 performs band-pass filter processing on the region image data that is the output of the AF gate unit 110 and extracts a high-frequency component. Then, the AF processing unit 112 generates a luminance difference component that is a difference between the maximum value and the minimum value of the luminance level in the region image data according to the high-frequency component, and generates a focus signal based on the luminance difference component. .

  Here, the focus signal is a signal representing the sharpness (contrast) of the area image data. Since the sharpness changes depending on the focus state of the imaging optical system, a focus signal representing the sharpness is used as an AF evaluation value of the imaging optical system.

  Further, the system control unit 115 specifies a focus position (also referred to as a focus position) based on the AF evaluation value calculated by the AF processing unit 112. Then, the system control unit 115 performs AF control by controlling the focus lens control unit 103 to move the focus lens along the optical axis.

  A VRAM (image display memory) 116 records format-converted image data (here, display image data). The operation display unit 117 performs image display, display for assisting operation, and display of the camera state under the control of the system control unit 115. The operation display unit 117 displays an image corresponding to the image data temporarily recorded in the VRAM 116 at the time of shooting as a shooting screen.

  The operation unit 118 includes a zoom operation member such as a zoom lever or a zoom switch in addition to a main switch for turning on / off the power. The zoom operation member is operated by the user, and the user instructs the system control unit 115 to perform zooming by the zoom operation member.

  The system control unit 115 obtains the zoom driving speed and the driving direction based on the operation amount and the operation direction of the zoom operation member, and the zoom lens control unit 101 controls the driving of the zoom lens along the optical axis. Further, the operation unit 118 is provided with an FA zoom switch for instructing the start and end of a framing assist zoom function (hereinafter referred to as an FA zoom function) that supports framing.

  When the FA zoom switch is instructed to start the FA zoom function, the system control unit 115 causes the face detection unit 111 to detect a person (for example, a face region) that is a subject on the imaging screen. The system control unit 115 obtains the position and size (size) of the face area detected by the face detection unit 111 on the imaging screen.

  When the face area does not fit on the imaging screen according to the position and size of the face area, the system control unit 115 causes the zoom lens control unit 101 to move the zoom lens along the optical axis so that the angle of view on the imaging screen becomes a wide angle. Drive control.

  Further, the system control unit 115 drives the zoom lens along the optical axis by the zoom lens control unit 101 so that the angle of view on the imaging screen becomes a wide angle when the size of the face area on the imaging screen becomes larger than a predetermined size. Control.

  On the other hand, when the size of the face area on the imaging screen is smaller than a predetermined size, the system control unit 115 causes the zoom lens control unit 101 to move the zoom lens along the optical axis so that the angle of view on the imaging screen becomes telephoto. Drive control.

  As a result, the operator who is a user only has to move the camera so that the person who is the subject is placed on the imaging screen without worrying about the zoom operation. Since the zoom position is automatically changed even if the frame is almost out, the angle of view can be easily adjusted.

  The face detection unit 111 performs a known face recognition process on the processed image data output from the image processing unit 106 to detect a human face area on the imaging screen. The face detection unit 111 performs face detection processing at a predetermined period such as one frame period or several frame periods.

  As described above, the detection result of the face area by the face detection unit 111 is sent to the system control unit 115. The face detection unit 111 extracts, for example, a skin color area based on the tone color of each pixel in the processed image data as the face verification process, and the skin contour area and a preset face contour plate The face area is detected based on the degree of matching with.

  Furthermore, the face detection unit 111 may perform face detection by extracting facial feature points such as eyes, nose, and mouth using known pattern recognition. Note that the face detection processing method is not limited to the above-described method, and other methods may be used.

  The system control unit 115 controls the AF gate unit 110 based on the detection result of the face area, and installs an AF frame at a position including the face area on the imaging screen. Further, the system control unit 115 controls the focus lens control unit 103 based on the AF evaluation value that is the output of the AF processing unit 112 to drive and control the focus lens along the optical axis to perform AF.

  A first switch (SW1) 113 shown in FIG. 1 is a switch for performing a shooting standby operation (shooting preparation operation) such as AF and AE. The second switch (SW2) 114 is a switch that is operated when imaging is performed after the first switch 113 is operated.

<FA zoom function>
FIG. 2 is a flowchart for explaining an example of the FA zoom performed by the camera shown in FIG. 2 is executed by the CPU according to a program stored in advance in the ROM in the system control unit 115.

  When the camera is turned on, the system control unit 115 acquires the presence / absence of an instruction (execution instruction) for executing the FA zoom function from the operation unit 118 (step S201). Then, the system control unit 115 determines whether or not there is an execution instruction (step S202).

  If there is no execution instruction (NO in step S202), the system control unit 115 returns to the process of step S201. On the other hand, when there is an execution instruction (YES in step S202), the system control unit 115 performs face detection processing on the latest photographed image by the face detection unit 111 to determine whether there is a face area (that is, whether there is a face detection result). Obtain (step S203).

  Subsequently, the system control unit 115 determines whether or not a face detection result exists, that is, whether or not the face detection is successful (step S204). If face detection is not successful (NO in step S204), system control unit 115 returns to the process in step S204.

  If the face detection is successful (YES in step S204), the system control unit 115 determines whether the size of the face area detected by the face detection unit 111 is larger than the first predetermined size (step S205). ). When the size of the face area is larger than the first predetermined size, the system control unit 115 causes the zoom lens control unit 101 to move the zoom lens to the optical axis in the direction in which the angle of view of the captured image (that is, the imaging screen) becomes wide. The drive is controlled along (step S206).

  At this time, the system control unit 115 drives the zoom lens by the movement amount of the zoom lens stored as a design value in the built-in ROM in advance. Then, the system control unit 115 returns to the process of step S201.

  If the size of the face area is equal to or smaller than the first predetermined size, the system control unit 115 determines whether the size of the face area is smaller than the second predetermined size (step S207). Here, the first predetermined size> the second predetermined size.

  If the size of the face area is greater than or equal to the second predetermined size (NO in step S207), system control unit 115 returns to the process of step S201. On the other hand, when the size of the face area is smaller than the second predetermined size (YES in step S207), the system control unit 115 causes the zoom lens control unit 101 to zoom the zoom lens in the direction in which the angle of view of the captured image becomes telephoto. Is controlled along the optical axis (step S208).

  At this time, the system control unit 115 drives the zoom lens by the movement amount of the zoom lens stored as a design value in the built-in ROM in advance. Then, the system control unit 115 returns to the process of step S201.

  In this way, when the FA zoom is performed, even when the subject to be photographed approaches the camera and the size of the subject changes, the position of the zoom lens (that is, the subject automatically) The shooting angle of view is changed, and the framing operation can be easily performed.

  Here, the size of the subject is determined using the face area detected by the face detection unit 111. You may make it determine the magnitude | size of a to-be-photographed object using another method.

<AF control>
FIG. 3 is a flowchart for explaining an example of AF control performed by the camera shown in FIG. Note that the processing in the flowchart shown in FIG. 3 is executed by the CPU in accordance with a program stored in advance in the ROM in the system control unit 115.

  When the AF control is started, the system control unit 115 acquires the presence / absence of an execution instruction for executing the FA zoom function from the operation unit 118 and determines whether or not there is an execution instruction. That is, the system control unit 115 determines whether or not FA zoom is being executed (step S301).

  If there is no FA zoom function execution instruction (NO in step S301), the system control unit 115 executes a normal AF sequence described later (step S302), and returns to the process of step S301. On the other hand, when there is an instruction to execute the FA zoom function (YES in step S301), the system control unit 115 executes an AF sequence for FA zoom described later (step S303) and returns to the process of step S301.

<Normal AF sequence>
FIG. 4 is a flowchart for explaining an example of the normal AF sequence shown in FIG.

  When the normal AF sequence is started, the system control unit 115 performs face detection processing on the latest photographed image by the face detection unit 111 and acquires the presence / absence of a face region (that is, presence / absence of a face detection result) (step S401). . Then, the system control unit 115 determines whether there is a face detection result, that is, whether the face detection is successful (step S402).

  If the face detection is successful (YES in step S402), an AF frame (hereinafter referred to as a face frame) that moves following the subject including the face area according to the position (position information) of the detected face area on the imaging screen. Is set in the AF gate unit 110 (step S403).

  Here, the center position of the area where the face area is detected may be used as the position information, and the positions of facial feature points such as eyes, nose and mouth may be used.

  FIG. 5 is a diagram for explaining the setting of a face frame corresponding to the face area detected by the face detection unit 111 shown in FIG. FIG. 5A is a diagram illustrating an example of face frame setting according to the face detection result, and FIG. 5B is a diagram illustrating another example of face frame setting according to the face detection result. FIG. 5C shows an example of a face frame set at the center of the angle of view.

  As shown in FIG. 5A, the system control unit 115 sets a face frame 600 on the shooting screen in accordance with the position information of the face area. In the illustrated example, the face area 603 faces the front (camera direction), and the face frame 600 is set at a position including the face area 603.

  Referring to FIG. 4 again, the system control unit 115 controls the AF processing unit 112 to acquire the AF evaluation value generated based on the image data in the area (area) defined by the face frame 600 (step S404). Then, the system control unit 115 sets a flag indicating that the face area is detected (hereinafter referred to as a face detection flag) in the built-in RAM (step S405). Subsequently, the system control unit 115 clears a face non-detection time described later and sets it to an initial value (that is, zero) (step S406).

  If face detection fails (NO in step S402), the system control unit 115 determines whether the face detection flag is set in the built-in RAM (step S407). If the face detection flag is set (YES in step S407), system control unit 115 sets a face frame holding time (first time threshold) that is a time for holding the face frame (step S408).

  This face frame holding time is a fixed value stored in advance as a design value in the ROM built in the system control unit 115.

  Next, the system control unit 115 determines whether or not the face non-detection time counted up as the continuation time during which the face area cannot be detected is shorter than the face frame holding time (step S409). If the face non-detection time is shorter than the face frame holding time (YES in step S409), system control unit 115 holds the face frame (that is, the position of the face frame) set in step S403 (step S410).

  As a result, as shown in FIG. 5B, even if the subject 604 moves, the position of the face frame 601 is displayed at the same position as the face frame 600. That is, even if the subject moves with the face area facing sideways and the face area cannot be detected, if the face non-detection time is smaller than the face frame holding time, the position of the face frame 601 is displayed at the same position as the face frame 600. Is done.

  Referring to FIG. 4 again, the system control unit 115 controls the AF processing unit 112 to acquire the AF evaluation value generated based on the image data in the area (area) defined by the face frame 601 (step S411). Then, the system control unit 115 counts up the face non-detection time (step S412).

  If the face detection flag is not set (NO in step S407), system control unit 115 sets an AF frame (hereinafter referred to as a normal frame) that does not follow the subject. That is, the system control unit 115 sets the face frame (normal frame) at a predetermined position on the imaging screen (step S413).

  For example, the system control unit 115 sets an AF frame (normal frame) in the AF gate unit 110 with a predetermined size stored in advance in the built-in ROM as a design value, and displays the normal frame at a predetermined position on the imaging screen. To do.

  Here, the position and size for displaying the normal frame are set as design values in advance. However, the user may instruct the position and size for setting the normal frame by the operation unit 118.

  Subsequently, the system control unit 115 controls the AF processing unit 112 to acquire an AF evaluation value generated based on image data in an area (area) defined by a normal frame set at a predetermined position. (Step S414). Then, the system control unit 115 clears the face detection flag (step S415).

  If the face non-detection time is equal to or longer than the face frame holding time (NO in step S409), the system control unit 115 proceeds to the process of step S413 and sets a normal frame.

  Subsequent to step S406, S412, or S415, the system control unit 115 executes AF processing described later based on the AF evaluation value acquired as described above (step S416). Thereafter, the system control unit 115 returns to the process of step S401.

  A known method is used for the AF process performed in step S416. For example, the system control unit 115 performs focus control by driving the focus lens with the focus lens control unit 103 so that the AF evaluation value becomes maximum while monitoring the AF evaluation value. In other words, the system control unit 115 performs focus control by searching for the peak value of the AF evaluation value by driving and controlling the focus lens by the focus lens control unit 103.

  In this AF process, in order to determine whether or not it is necessary to re-drive the focus lens in a state where the focus is obtained, the focus is maintained such as whether or not the AF evaluation value has been reduced. Processing is also included.

  As described above, in the normal AF sequence, AF control is performed with the face frame held for a predetermined time after face detection failure. As a result, a situation in which the AF frame (face frame) is frequently switched due to an influence such as a change in the face state of the subject (for example, it turned sideways) or a face detection failure caused by the user's hand play. Can be prevented.

<FA zoom AF sequence>
FIG. 6 is a flowchart for explaining an example of the AF sequence for FA zoom shown in FIG.

  When the FA zoom AF sequence is started, the system control unit 115 performs face detection processing on the latest photographed image by the face detection unit 111 and acquires the presence / absence of a face region (that is, presence / absence of a face detection result) (step S501). ). Then, the system control unit 115 determines whether or not a face detection result exists, that is, whether or not the face detection is successful (step S502).

  If the face detection is successful (YES in step S502), a face frame (AF frame) that moves following the subject including the face area according to the position (position information) of the detected face area on the imaging screen. Is set in the AF gate unit 110 (step S503).

  As described above, as the position information, the center position of the area where the face area is detected may be used, or the positions of facial feature points such as eyes, nose, and mouth may be used. Then, the face frame 600 is set on the shooting screen as shown in FIG. 5A by setting the face frame by the processing in step S503.

  Subsequently, the system control unit 115 controls the AF processing unit 112 to acquire an AF evaluation value generated based on the image data in the area (area) defined by the face frame 600 (step S504). Then, the system control unit 115 sets the face detection flag built-in RAM (step S505).

  If the face detection fails (NO in step S402), the system control unit 115 determines whether the face detection flag is set in the built-in RAM (step S506). When the face detection flag is set (YES in step S506), the system control unit 115 sets the AF frame (frame region) with a predetermined size at the center of the shooting angle of view (first region) as a normal frame. Is set in the AF gate unit 110 (step S507).

  Here, the size for displaying the normal frame is set as a design value in advance, but the user may instruct the size for setting the normal frame by the operation unit 118.

  As shown in FIG. 5C, the face frame (normal frame) 602 is set at the center of the angle of view. In the example shown in the figure, the subject 604 moves with the face area facing sideways and reaches the center of the imaging screen, so the area of the face frame 602 includes the face area.

  Referring to FIG. 6 again, the system control unit 115 controls the AF processing unit 112 to acquire an AF evaluation value generated based on the image data in the area (area) defined by the face frame 602 (step). S508).

  If the face detection flag is not set (NO in step S506), system control unit 115 sets a normal frame that does not follow the subject. That is, the system control unit 115 sets the face frame (normal frame) at a predetermined position on the imaging screen (step S509).

  As described above, the system control unit 115 sets the normal frame in the AF gate unit 110 with a predetermined size stored in advance in the built-in ROM as a design value, and displays the normal frame at a predetermined position on the imaging screen. . Here, the position and size for displaying the normal frame are set as design values in advance. However, the user may instruct the position and size for setting the normal frame by the operation unit 118.

  Subsequently, the system control unit 115 controls the AF processing unit 112 to acquire an AF evaluation value generated based on image data in an area (area) defined by a normal frame set at a predetermined position. (Step S510). Then, the system control unit 115 clears the face detection flag (step S511).

  Subsequent to step S505, S508, or S511, the system control unit 115 executes AF processing in the same manner as in step S416 based on the AF evaluation value acquired as described above (step S512). Thereafter, the system control unit 115 returns to the process of step S501.

  As described above, in the FA zoom AF sequence, when face detection fails, an AF frame is set at the center of the shooting angle of view and AF control is performed.

  By the way, the FA zoom function is a function that facilitates framing when a user photographs a specific subject. Therefore, when the execution of the FA zoom function is instructed by the user, there is a high possibility that the subject is framed within the shooting field angle range. That is, even if face detection fails during the FA zoom, the possibility that the subject is out of frame is low. In this case, there is a high possibility that face detection has failed for some reason.

  Furthermore, when the subject being photographed approaches the camera and the size of the subject being photographed changes, the user shoots the camera to frame the subject as close to the center of the field of view as possible. The direction should be adjusted.

  Therefore, in AF control when the execution of the FA zoom function is instructed, that is, in the FA zoom AF sequence, if the AF frame is set at the center of the shooting angle of view when face detection fails, shooting is in progress. It is possible to increase the possibility of focusing on the subject.

  As described above, in the first embodiment of the present invention, in the AF control when the execution of the FA zoom function is not instructed, that is, in the normal AF sequence, the face is detected for a predetermined time after the face detection fails. AF control is performed with the frame held. This prevents a situation where the AF frame is frequently switched due to a change in the face state of the subject (for example, when the subject is turned sideways) or a face detection failure due to a camera shake of the user. it can.

  On the other hand, in the AF control when the execution of the FA zoom function is instructed, that is, in the AF sequence for FA zoom, when face detection fails, the AF frame is set at the center of the shooting angle of view. The possibility of focusing on the subject being shot can be increased.

[Second Embodiment]
Next, an example of a camera according to the second embodiment of the present invention will be described. The configuration of the camera according to the second embodiment is the same as that of the camera shown in FIG. The FA zoom performed by the camera according to the second embodiment is the same as the process described in FIG.

<AF control>
FIG. 7 is a flowchart for explaining AF control performed by the camera according to the second embodiment of the present invention. Note that the processing in the flowchart shown in FIG. 7 is executed by the CPU according to a program stored in advance in the ROM in the system control unit 115.
Further, in the flowchart shown in FIG. 7, the same steps as those in the flowchart shown in FIG.

  When the AF control is started, the system control unit 115 acquires a shooting mode by a user operation from the operation unit 118 (step S701). Then, the system control unit 115 determines whether the shooting mode is the still image shooting mode or the moving image shooting mode (step S702).

  If the shooting mode is the moving image shooting mode (YES in step S702), system control unit 115 proceeds to the process of step S301 described above, and determines whether FA zoom is being executed. If the FA zoom is being executed, the system control unit 115 proceeds to the process of step S303 and executes the FA zoom AF sequence. On the other hand, if the FA zoom is not being executed, the system control unit 115 proceeds to the process of step S302 and executes the normal AF sequence.

  If the shooting mode is not the moving image shooting mode (NO in step S702), that is, the shooting mode is the still image shooting mode, the system control unit 115 proceeds to the process of step S302 and executes the normal AF sequence.

  As described above, in the second embodiment of the present invention, AF control is performed when the shooting mode is the still image shooting mode and when the shooting mode is the moving image shooting mode and the execution of the FA zoom function is not instructed. A normal AF sequence is performed. That is, AF control is performed with the face frame held for a predetermined time after face detection failure.

  Accordingly, it is possible to prevent a situation in which the AF frame is frequently switched due to an influence of a change in the face state of the subject or a face detection failure due to a user's camera shake.

  On the other hand, when the shooting mode is the moving image shooting mode and execution of the FA zoom function is instructed, an AF sequence for FA zoom is performed as AF control. That is, when face detection fails, the AF frame is set at the center of the shooting angle of view, so that the possibility of focusing on the subject being shot can be increased.

  In the above embodiment, in the AF sequence for FA zoom, the AF frame is set at the center of the shooting angle of view when face detection fails. For example, the system control unit 115 may always calculate the amount of motion of the subject (including the direction of motion) according to the motion vector of the subject while the face detection is successful. Then, the system control unit 115 temporarily stores the amount of movement in a memory or the like. After failing to detect the face, the system control unit 115 estimates the position of the subject (face position) according to the amount of movement (including the movement direction) stored in the memory, and sets the AF frame at the estimated position. It may be.

  As is clear from the above description, in the example shown in FIG. 1, the imaging processing unit 105, the image processing unit 106, the face detection unit 111, the system control unit 115, and the zoom lens control unit 101 function as framing means. In addition, the imaging processing unit 105, the image processing unit 106, the face detection unit 111, the system control unit 115, the AF gate 110, the AF processing unit 112, and the focus lens control unit 103 function as a focus adjustment unit.

  Further, the face detection unit 111 functions as a subject detection unit, and the system control unit 115, the AF processing unit 112, and the AF gate 110 function as a setting unit. The operation unit 118 and the system control unit 115 function as a shooting mode selection unit, and the imaging processing unit 105 and the system control unit 115 function as a motion detection unit and an estimation unit.

  The imaging lens 100, zoom lens, diaphragm, shutter, and focus lens shown in FIG. 1 constitute an imaging optical system.

  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.

  Each of the above control method and control program has at least a framing step, a focus adjustment step, a subject detection step, and a setting step.

  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 a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

DESCRIPTION OF SYMBOLS 100 Shooting lens unit 101 Zoom lens control part 103 Focus lens control part 104 Image pick-up element 105 Imaging process part 106 Image processing part 110 AF gate part 111 Face detection part 112 AF process part 115 System control part

Claims (9)

An imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens,
Framing means for moving the zoom lens along the optical axis of the imaging optical system and framing the subject at a shooting angle of view in a captured image;
Focus adjusting means for adjusting the focus by moving the focus lens along the optical axis in accordance with image data corresponding to a partial area in the captured image;
Subject detection means for detecting the subject in the captured image;
When the subject is not detected from the state in which the subject is detected by the subject detection unit, if the framing by the framing unit is being executed, the partial area of the captured image is determined in advance. Setting means for setting the first area as a frame area;
An imaging device comprising:   The setting means sets the partial area as a predetermined area of the captured image as the frame area when the framing by the framing means is being executed in a state where the subject is not detected by the subject detection means. The imaging apparatus according to claim 1.   The setting means sets the partial area as an area including the subject as the frame area when framing by the framing means is being executed while the subject is detected by the subject detection means. The imaging apparatus according to claim 1 or 2, wherein A shooting mode selection means for selecting one of still image shooting and moving image shooting when imaging the subject;
When the moving image shooting is selected by the shooting mode selection unit, the setting unit performs framing by the framing unit when the subject is not detected from the state where the subject is detected by the subject detection unit. The imaging apparatus according to any one of claims 1 to 3, wherein the first area is set as the frame area when it is in the middle.   The imaging apparatus according to claim 1, wherein the first region is a central portion of the shooting angle of view.   The imaging apparatus according to claim 1, wherein the subject detection unit detects a face area of the subject. Motion detection means for obtaining a motion amount and a motion direction of the subject as motion information according to a motion vector of the subject and storing the motion information in a memory in a state where the subject is detected by the subject detection means;
Estimation means for estimating the position of the subject in the captured image according to the motion information stored in the memory when the subject detection means is in a state where the subject is not detected;
The imaging apparatus according to claim 1, wherein the setting unit sets the frame region at a position estimated by the estimation unit. A method for controlling an imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens,
A framing step of moving the zoom lens along the optical axis of the imaging optical system and framing the subject at a shooting angle of view in a captured image;
A focus adjustment step of performing focus adjustment by moving the focus lens along the optical axis in accordance with image data corresponding to a partial region in the captured image;
A subject detection step of detecting the subject in the captured image;
When the subject is not detected from the state in which the subject is detected in the subject detection step, if the framing by the framing step is being executed, the partial area is determined in advance in the captured image. A setting step for setting the first region as a frame region;
A control method characterized by comprising: A control program used in an imaging apparatus that images a subject via an imaging optical system including at least a zoom lens and a focus lens,
In the computer provided in the imaging device,
A framing step of moving the zoom lens along the optical axis of the imaging optical system and framing the subject at a shooting angle of view in a captured image;
A focus adjustment step of performing focus adjustment by moving the focus lens along the optical axis in accordance with image data corresponding to a partial region in the captured image;
A subject detection step of detecting the subject in the captured image;
When the subject is not detected from the state in which the subject is detected in the subject detection step, if the framing by the framing step is being executed, the partial area is determined in advance in the captured image. A setting step for setting the first region as a frame region;
A control program characterized by causing

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