JP2010197467A - Image capturing apparatus, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a moving object which is not required as a tracking object by a user from being erroneously determined as a tracking object. <P>SOLUTION: In an image capturing apparatus 100, a search block (n) is set on the present frame image so that the center of the search block S(n) may be shifted from the center O(n-1) of the tracking block P(n-1) in the previous frame image in either of four directions according to the user's operation of pressing a cross button 26. By having the constitution, even if the second object OB2 which is not required as the tracking object by the user moves on the frame image and overlaps with the first object OB1 which is required as the tracking object by the user, the second object OB2 is removed from the search block, accordingly, the second object OB2 is prevented from being erroneously tracked. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photographing apparatus that tracks a subject image.

  A tracking process for tracking the movement of a specific subject in frame images sequentially photographed by a photographing apparatus is known. Such tracking processing is used, for example, to perform autofocus while tracking the movement of a moving subject.

  A conventional tracking method will be briefly described. In the conventional tracking process, first, an image of a subject that appears in a specific area of a frame image that is first captured is initially set as an image to be tracked. Thereafter, in the tracking process, pattern matching is performed between an image to be tracked in the previous frame image and an image in a predetermined search block in the current frame image. An area in the current frame image in which the degree of correlation with the image to be tracked in the previous frame image is determined to be greater than or equal to the threshold by pattern matching is set as the image to be tracked in the current frame image. Thereafter, by repeating this process, the moving subject is tracked.

  As a technique related to this tracking process, in Patent Document 1, when a moving object to be tracked enters a specific area specified in advance on a captured image, the tracking process is stopped until the moving object comes out of the specific area. Thus, a technique has been proposed in which the moving object is tracked again after the moving object leaves the specific area.

  For example, if a moving object that is a tracking target overlaps with a swaying vegetation on a frame image, the moving object and the swaying vegetation cannot be distinguished, so that the vegetation is erroneously determined to be a tracking target. there is a possibility. However, according to the technique described in Patent Document 1, even in such a case, if a vegetation swaying in the wind is specified as a specific region, the moving object to be tracked and the vegetation swaying in the wind overlap each other. Since the tracking process is stopped, it is possible to reduce the possibility that a swaying vegetation is erroneously determined to be the tracking target.

JP 2006-311099 A

  However, in the technique described in Patent Document 1, a predetermined area around a specific area is set as a search block, and pattern matching is performed on the search block so that a moving object that has left the specific area is detected again. ing. For this reason, in the technique described in Patent Document 1, for example, when a moving first subject that is a tracking target and a moving second subject that is not a tracking target intersect, a second subject that is not originally a tracking target. May enter a search block set around a specific area. In this case, since the second subject is subject to pattern matching when the tracking process is resumed, there is a possibility that the second subject that is not originally the subject of tracking may be mistakenly tracked. It was.

  Accordingly, an object of the present invention is to prevent erroneous determination that a moving user-desired subject is a tracking target.

In order to achieve the above object, the present invention provides:
Photographing means for sequentially photographing frame images of the subject;
Operation means for accepting a user operation and instructing a direction according to an operation accepted from the user among a plurality of directions;
First setting means for setting a search block at a position corresponding to the direction instructed by the operation means with respect to the frame image;
Second setting means for sequentially setting a tracking block for tracking a subject with respect to the frame image in accordance with a result of a matching process between a template image and an image of a search block set by the setting means;
It is characterized by providing.

  According to the present invention, it is possible to prevent a moving user's undesired subject from being erroneously determined as a tracking target.

It is a figure which shows the external appearance of the imaging device which concerns on embodiment of this invention. It is a block diagram which shows the function structure of the imaging device which concerns on embodiment of this invention. It is a figure for demonstrating the method of the tracking process which concerns on embodiment of this invention. It is a figure for demonstrating the method of the tracking process which concerns on embodiment of this invention. It is a figure for demonstrating the method of the tracking process which concerns on embodiment of this invention. It is a figure which shows the flow of a process in tracking AF mode which concerns on embodiment of this invention. It is a figure which shows the procedure of the tracking process which concerns on embodiment of this invention. It is a figure which shows the example of the tracking block and search block which are initially set in a tracking process. It is a figure which shows the example of the search block set to a frame image. It is a figure which shows the example of the search block set to a frame image. It is a figure for demonstrating the method of the tracking process which concerns on the modification of this invention.

  Hereinafter, based on the drawings, a photographing apparatus 100 according to an embodiment of the present invention will be described.

  FIG. 1 is a diagram illustrating an external appearance of a photographing apparatus 100 according to the present embodiment. As shown in FIG. 1, a cross button 26a, a menu button 26c, and a liquid crystal display 28a are provided on the back of the photographing apparatus 100.

  The cross button 26a includes a left button 261a, a lower button 262a, a right button 263a, and an upper button 264a which are four buttons arranged in a cross shape. The cross button 26a is operated to move the cursor for the user to select various items displayed on the menu screen. In the present embodiment, the cross button 26a is operated to set a search block to be subjected to pattern matching in the tracking process as a frame image. The menu button is operated when a menu screen is displayed on the liquid crystal display 28a. The liquid crystal display 28a is used as an electronic viewfinder that displays a live view image in the shooting mode, and displays a recorded shot image in the playback mode.

  A shutter button 26b is provided on the upper surface of the photographing apparatus 100. The shutter button 26b is configured to accept from the user a half-pressing operation for instructing shooting preparation (focusing operation or the like) and a full-pressing operation for instructing shooting.

  FIG. 2 is a block diagram illustrating a functional configuration of the photographing apparatus 100 according to the present embodiment. The configuration of the photographing apparatus 100 will be described with reference to FIG. The photographing apparatus 100 can be configured by a digital camera or the like.

  The photographing apparatus 100 includes a control unit 10, a RAM 11, a ROM 12, an optical lens device 13, an optical system control unit 14, an optical system drive unit 15, a shutter device 16, a shutter control unit 17, and a shutter drive unit. 18, an image sensor 19, an image sensor drive unit 20, a pre-processing unit 21, an image input controller 22, an image memory 23, an image processing unit 24, an AF evaluation unit 25, an operation unit 26, and a display A control unit 27, a display unit 28, a recording medium 29, and a subject tracking unit 30 are provided.

  The control unit 10 controls the overall operation of the image capturing apparatus 100. The control unit 10 includes a CPU (Central Processing Unit), a real-time clock (Real Time Clock) that is a timing circuit, and the like.

  The RAM 11 functions as a working area when the control unit 10 executes each process. The RAM 11 is composed of a DRAM (Dynamic Random Access Memory) or the like. The ROM 12 stores programs and data necessary for the photographing apparatus 100 to execute each process. The ROM 12 is composed of a flash memory or the like. The control unit 10 uses the RAM 11 as a working area to execute each process in cooperation with a program stored in the ROM 12.

  The optical lens device 13 includes a focus lens, a zoom lens, and the like. The focus lens is a lens for forming a subject image on the light receiving surface of the image sensor 19.

  The optical system control unit 14 controls the optical system driving unit 15 according to the control by the control unit 10 to cause the optical system driving unit 15 to advance and retract the focus lens of the optical lens device 13 in the optical axis direction. Thereby, the position of the focus lens changes to adjust the focus. The optical system driving unit 13 is configured by a stepping motor or the like. The optical system control unit 14 includes a control circuit that controls the optical system driving unit 15.

  The shutter device 16 is a mechanism that functions as a mechanical shutter that blocks a light beam incident on the image sensor 19 and also functions as an aperture that adjusts the amount of light beam incident on the image sensor 19. The shutter device 16 includes shutter blades and the like.

  The shutter control unit 17 drives the shutter drive unit 18 according to control by the control unit 10. Specifically, the shutter control unit 17 controls the shutter drive unit 18 according to the control by the control unit 10 to cause the shutter drive unit 18 to open and close the shutter blades of the shutter device 16. Further, the shutter control unit 17 controls the shutter drive unit 18 according to the control by the control unit 10, thereby causing the shutter drive unit 18 to adjust the aperture of the shutter device 16. The shutter drive unit 18 includes an electromagnetic actuator that opens and closes shutter blades. The drive control unit 17 includes a circuit that supplies a current to the shutter drive unit 18.

  The image sensor 19 is an element that photoelectrically converts (shoots) a subject image that is incident from the optical lens device 13 and formed on the light receiving surface. On the light receiving surface of the image sensor 19, photodiodes that are photoelectric conversion elements are arranged in a matrix. These photodiodes constitute each pixel of the image sensor 19. On each photodiode, color filters of R (red), G (green), and B (blue) are arranged according to the Bayer arrangement. The image sensor 19 photoelectrically converts the subject image at predetermined time intervals to store image signals according to control by the image sensor driving unit 20, and sequentially outputs the stored image signals. The image sensor 19 is composed of a CCD (Charge Coupled Device) type image sensor or the like.

  The image sensor driving unit 20 drives the image sensor 19 according to the control by the control unit 10. The image sensor driving unit 20 generates various clock pulses and the like according to control by the control unit 10. The image sensor driving unit 20 reads an image signal from the image sensor 19 at regular intervals based on the generated various clock pulses and the control signal supplied from the control circuit 10. The image sensor driving unit 20 includes a timing generator that generates various clock pulses, a scanning circuit, and the like.

  The pre-processing unit 21 performs various signal processing such as correlated double sampling processing, gain control processing, and A / D (Analog / Digital) conversion processing on the image signal supplied from the image pickup device 19 to obtain a digital signal. Generate and output the generated digital signal. The preprocessing unit 21 is configured by an A / D converter or the like.

  The image input controller 22 stores the digital signal supplied from the preprocessing unit 21 in the image memory 23.

  The image memory 23 temporarily stores the image signal generated by the preprocessing unit 21 and the image data generated by the image processing unit 24. The image memory 23 is also used as a working area when the image processing unit 24 generates image data from Bayer data. The image memory 21 includes a DRAM (Dynamic Random Access Memory) or the like.

  The image processing unit 24 performs image processing such as white balance correction processing, γ correction processing, and YC conversion processing on the image signal stored in the image memory 23 to obtain image data in which the luminance signal and the color difference signal are superimposed. Generate. An image represented by this image data is a frame image. Further, the image processing unit 24 generates a large-capacity frame image with a relatively high image quality when the shutter button 26b is fully pressed. On the other hand, when displaying the live view image, the image processing unit 24 generates a frame image having a relatively low image quality and a small capacity. The image processing unit 24 includes a DSP (Digital Signal Processor) or the like.

  The AF evaluation unit 25 extracts a high-frequency component by passing a luminance signal corresponding to a predetermined AF frame in the frame image through a high-pass filter, and calculates an integrated value of absolute values of the extracted high-frequency component. The AF evaluation unit 25 supplies the calculated integrated value to the control unit 10 as an AF evaluation value. The control unit 10 controls the optical system drive unit 15 via the optical system control unit 14 during the focusing operation, thereby causing the optical system drive unit 15 to advance and retract the focus lens in the optical axis direction. Then, the control unit 10 causes the AF evaluation unit 25 to calculate an AF evaluation value from a frame image taken when the focus lens is at each lens position. Then, the control unit 10 stops the focus lens at the lens position where the AF evaluation value supplied from the AF evaluation unit 25 is the highest.

  The operation unit 26 receives various button operations from the user. The operation unit 26 includes a power button (not shown), a cross button 26a, a shutter button 26b, a menu button 26c, and the like. The operation unit 26 supplies a signal corresponding to the operation received from the user to the control unit 10. For example, when the operation unit 26 receives an operation of the left button 261a of the cross button 26a by the user, the operation unit 26 supplies a signal indicating the left direction to the control unit 10. Similarly, when the operation unit 26 receives an operation of the lower button 262a, the right button 263a, and the upper button 264a of the cross button 26a by the user, the operation unit 26 indicates a signal indicating the downward direction, a signal indicating the right direction, A signal indicating the upward direction is supplied to the control unit 10. When these signals are received from the operation unit 26, the control unit 10 executes processing based on the received signals.

  The display control unit 27 converts the image data stored in the image memory 23 into an analog signal and outputs it under the control of the control unit 10. The display control unit 27 includes a VRAM (Video Random Access Memory), a D / A (Digital / Analog) converter, and the like.

  The display unit 28 displays an image or the like expressed by the analog signal supplied from the display control unit 27. The display unit 28 includes a liquid crystal display 28 a provided on the back surface of the photographing apparatus 100.

  The recording medium 29 records the image data generated by the image processing unit 24. The recording medium 29 includes a semiconductor memory card that can be attached to and detached from the photographing apparatus 100.

  The subject tracking unit 30 tracks subjects that appear in frame images that are sequentially captured. The subject tracking unit 30 includes a search block setting unit 30a, a matching determination unit 30b, a tracking image memory 30c, and a tracking block setting unit 30d.

  A tracking processing method according to the present embodiment performed by the subject tracking unit 30 will be described with reference to FIGS. 3 to 5.

  Now, every time the frame period elapses, the first, second, third,..., (N−1) th, nth, (n + 1) th frames are visited in this order (n is 2). Or an integer). Then, the captured images obtained in the first, second, third,..., (N−1) th, nth frame, and (n + 1) th are respectively converted into a frame image F (1) and a frame image. F (2), frame image F (3),..., Frame image F (n−1), frame image F (n), and frame image F (n + 1). In the following description, it is assumed that the frame image F (n) is taken at the current time point, this frame image F (n) is called the current frame image F (n), and the frame image F (n−1) is The previous frame image F (n + 1) is called, and the frame image F (n + 1) is called the next frame image F (n + 1).

  In FIG. 3, the symbol F (n−1) indicates the previous frame image F (n−1). A symbol P (n−1) indicates a tracking block set in the previous frame image F (n−1). The tracking block is sequentially set for each frame image so as to track the movement of the subject that is the tracking target. A symbol O (n−1) indicates the center of the tracking block P (n−1).

  4 and 5, the symbol F (n) indicates the current frame image F (n). Symbol S (n) represents a search block that is an area in which the tracking block P (n−1), which is a template image, can move in pattern matching in tracking processing. In the present embodiment, the size of the search block S (n) set for each frame image is assumed to be equal to the size of one image area of each image area obtained by dividing the frame image into nine.

  The matching determination unit 30b performs pattern matching to calculate a correlation value E between the tracking block P (n-1) that is a template image and the search block S (n). At the time of pattern matching, the matching determination unit 30b moves the tracking block P (n-1), which is a template image, in the search block S (n) one pixel at a time in the horizontal direction or the vertical direction, so that the template image is one pixel. Correlation value E is calculated every time it moves. The correlation value E1 is, for example, a sum of absolute values of luminance differences between pixels at the same position between the template image and the search block S (n). This correlation value E is generally called SAD (Sum of Absolute Difference). Note that the correlation value may be obtained by the sum of squares of luminance difference (Sum of Squared Difference) or the like.

  The correlation value E (such as the luminance difference of each pixel) decreases as the similarity between the tracking block P (n−1), which is a template image, and the search block S (n) increases. Therefore, if the position in the search block S (n) having the smallest correlation value E is obtained, the most similar image of the tracking block P (n−1) is located in the search block S (n) of the current frame image. It can be determined whether it is located. After the pattern matching is completed, the matching determination unit 30b supplies a signal indicating the position where the correlation value E is the smallest in the search block S (n) to the tracking block setting unit 30d.

  The tracking block setting unit 30d has, for the current frame image F (n), the position indicated by the signal supplied from the matching determination unit 30b (the position in the search block S (n) where the correlation value E is the smallest). A tracking block P (n) is set.

  The tracking image memory 30c stores image data representing an image in the tracking block. The tracking block setting unit 30d cuts out an image in the tracking block from the frame image every time a tracking block is set for the frame image. Then, the image data representing the clipped image is stored in the tracking image memory 30c as a template image for pattern matching performed on the next frame image. As a result, the template image stored in the tracking image memory 30c is updated to the latest one. When performing pattern matching, the matching determination unit 30b reads an image in a tracking block that is a template image from the tracking image memory 30c, and performs pattern matching between the read image and a search block in a frame image.

  Here, in the tracking process according to the present embodiment, the search block setting unit 30a specifies the center of the search block S (n) in accordance with the user's operation of the cross button 26a. Then, the search block setting unit 30a sets the search block S (n) for the current frame image F (n) with the designated center as the center of the search block S (n). Thus, the search block S (n) is set at a different position in accordance with a different operation of the cross key 26a by the user. By repeating such processing, while the cross key 26a is operated by the user, the search block S (n) is positioned at a position corresponding to the operation of the cross button 26a of the user with respect to each sequentially captured frame image. Are set sequentially.

  FIG. 4 is a diagram illustrating an example of the search block S (n) that is set when the cross button 26a is operated by the user.

  When the user operates the left button 261a of the cross button 26a, the control unit 10 receives a signal (a signal indicating the left direction) according to the operation of the left button 261a and sets the received signal as a search block. To the unit 30a. In this case, for example, as shown in FIG. 4A, the search block setting unit 30a determines the position of the right end portion of the search block S (n) in the horizontal direction in response to the signal supplied from the control unit 10. The center of the search block S (n) is designated so as to coincide with the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). Then, the search block setting unit 30a sets the search block S (n) for the current frame image F (n) with the designated center as the center of the search block S (n). At this time, the position in the vertical direction of the center of the set search block S (n) matches the position of the center O (n−1). Thus, the search is performed so that the center of the search block S (n) is arranged on the left side of the center O (n−1) of the tracking block P (n−1) according to the operation of the left button 261a by the user. Block S (n) is set.

  Similarly, when the user operates the lower button 262a of the cross button 26a, the search block setting unit 30a in the vertical direction of the upper end portion of the search block S (n) as shown in FIG. 4B. The center of the search block S (n) is designated so that the position matches the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). As a result, the current frame image F (n) is arranged such that the center of the search block S (n) is located below the center O (n−1) of the tracking block in the previous frame image F (n−1). A search block S (n) is set for. At this time, the position in the horizontal direction of the center of the set search block S (n) coincides with the position of the center O (n−1).

  Further, when the right button 263a of the cross button 26a is operated by the user, the search block setting unit 30a indicates that the position in the horizontal direction of the left end portion of the search block S (n) is as shown in FIG. The center of the search block S (n) is designated so as to coincide with the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). Thereby, the center of the search block S (n) is arranged in the current frame image F (n) so as to be arranged on the right side of the tracking block center O (n−1) in the previous frame image F (n−1). On the other hand, a search block S (n) is set. At this time, the position in the vertical direction of the center of the set search block S (n) coincides with the position of the center O (n−1).

  When the upper button 264a of the cross button 26a is operated by the user, the search block setting unit 30a determines that the position of the lower end portion of the search block S (n) in the vertical direction is as shown in FIG. The center of the search block S (n) is designated so as to coincide with the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). As a result, the current frame image F (n) is arranged such that the center of the search block S (n) is arranged above the center O (n-1) of the tracking block in the previous frame image F (n-1). On the other hand, a search block S (n) is set. At this time, the position in the horizontal direction of the center of the set search block S (n) coincides with the position of the center O (n−1).

  FIG. 5 is a diagram illustrating an example of the search block S (n) set when the cross button 26a is not operated by the user. When the cross button 26a is not operated by the user, the search block setting unit 30a sets the center O (n-1) of the tracking block in the previous frame image F (n-1) as the center of the search block S (n). specify. Then, as shown in FIG. 5, the search block setting unit 30a sets the search block S (n) for the current frame image F (n) with the designated center as the center of the search block S (n). . Thereby, when the cross button 26a is not operated by the user, the center of the search block S (n) matches the center O (n-1) of the tracking block in the previous frame image F (n-1). A search block S (n) is set.

  FIG. 6 is a flowchart showing the flow of processing in the tracking AF mode of the imaging apparatus 100 according to the present embodiment. A process flow in the tracking AF mode executed by the image capturing apparatus 100 will be described with reference to FIG.

  When the tracking AF mode is set by a predetermined operation of the user's operation unit 26, the photographing apparatus 100 reads a program stored in the ROM 12 and starts processing of the tracking AF mode in cooperation with this program. .

  First, in step S1, the control unit 10 starts live view display. Specifically, the control unit 10 sequentially supplies frame images sequentially generated by the image processing unit 24 to the display control unit 27, thereby causing the display control unit 27 to display the frame image as a live view image on the display unit 28. Display.

  Next, in step S2, the control unit 10 determines whether or not the user has pressed the shutter button 26b halfway. Specifically, the control unit 10 determines whether or not the shutter button 26b is half-pressed by the user by monitoring a signal corresponding to the half-press operation of the shutter button 26b from the operation unit 26. When it is determined that the shutter button 26b is not half-pressed (step S2: NO), the control unit 10 continues the live view display until a signal corresponding to the half-press operation of the shutter button 26b is detected. On the other hand, when the control unit 10 determines that the shutter button 26b is half-pressed (step S2: YES), the process proceeds to step S3.

  Next, in step S <b> 3, the control unit 10 performs an initial setting of the tracking process. Specifically, the control unit 10 causes the tracking block setting unit 30d to cut out an image within an AF frame defined in a predetermined central area on the frame image taken at the time of step S3, and this cut-out image Is stored in the first tracking image memory 30c as image data of the tracking block that is initially set. In addition, the control unit 10 causes the tracking block setting unit 30d to set the image region located in the center among the image regions obtained by dividing the frame image captured at the time of step S3 into nine as search blocks in the initial state.

  In the present embodiment, first, by changing the posture of the photographing apparatus 100 that the user holds in his / her hand, the face of the subject that the user desires to track is within the AF frame located in the central region of the live view image. Adjust the composition so that it fits. When the user presses the shutter button 26b halfway in this state, the control unit 10 causes the tracking block setting unit 30d to cut out the image in the AF frame from the frame image, and uses the cut out image as a tracking block as a tracking image memory. Store in 30c. In the present embodiment, the size of the tracking block is equal to the size of the AF frame.

  Furthermore, the control unit 10 displays an outer frame that defines the boundary line of the initially set search block on the frame image. Thereafter, every time a search block is set for each frame image, the control unit 10 causes the outer frame of the set search block to be displayed on the frame image.

  FIG. 8 is a diagram illustrating an example of a tracking block and a search block that are set as initial settings for tracking processing. Reference numeral F (1) denotes a first frame image that is first taken after the control unit 10 detects a half-pressing operation of the shutter button 26b. In this frame image F (1), a subject OB1 that the user desires to track and a subject OB2 that the user does not want to track are shown. The code P (1) is a tracking block that is initially set for the frame image F (1). Reference sign S (2) is a search block that is initially set for the second frame image F (2). An image region located in the center among the image regions obtained by dividing the frame image into nine is set as a search block S (2) to be initialized. At this time, as indicated by a solid line in FIG. 8, the outer frame of the search block S (2) is displayed on the frame image F (1).

  In step S3, the control unit 10 performs a focusing operation as an initial setting for the tracking process. During the focusing operation, the control unit 10 causes the AF evaluation unit 25 to calculate an AF evaluation value from the luminance signal corresponding to the AF frame in the image signals sequentially generated at the time of step S3. Then, the control unit 10 controls the optical system driving unit 15 via the optical system control unit 14 to cause the optical system driving unit 15 to advance and retract the focus lens in the optical axis direction, and is supplied from the AF evaluation unit 25. The focus lens is stopped at the lens position with the highest AF evaluation value. As a result, the subject's face within the AF frame is focused.

  Returning to FIG. 6, next, in step S <b> 4, the control unit 10 executes a tracking process. The detailed procedure of this tracking process will be described later. As will be described later, since the AF frame is set at the same position as the tracking block by this tracking process, the AF frame follows the movement of the subject.

  Next, in step S5, the control unit 10 determines whether or not a predetermined time (for example, 3 seconds) has elapsed. Specifically, the control unit 10 determines whether or not the elapsed time from the time when the focusing operation immediately before indicated by the timing circuit in the control unit 10 has reached a predetermined time or not. . When it is determined that the predetermined time has not elapsed (step S5: NO), the control unit 10 advances the process to step S7. On the other hand, when the control unit 10 determines that the predetermined time has elapsed (step S5: YES), the control unit 10 proceeds to step S6.

  In step S6, the control unit 10 performs a focusing operation. Specifically, the control unit 10 causes the AF evaluation unit 25 to extract an AF evaluation value from the luminance signal corresponding to the AF frame (tracking block) on the frame images sequentially captured at the time of step S6. Then, the control unit 10 controls the optical system driving unit 15 via the optical system control unit 14 to cause the optical system driving unit 15 to advance and retract the focus lens in the optical axis direction, and is supplied from the AF evaluation unit 25. The focus lens is stopped at the lens position with the highest AF evaluation value. Thereby, the subject's face in the AF frame (tracking block) is focused.

  Next, in step S7, the control unit 10 determines whether or not the shutter button 26b is fully pressed by the user. Specifically, the control unit 10 determines whether or not the shutter button 26b is fully pressed by the user by monitoring a signal corresponding to the full-pressing operation of the shutter button 26b from the operation unit 26. When it is determined that the shutter button 26b has not been fully pressed (step S7: NO), the control unit 10 returns the process to step S4. On the other hand, when the control unit 10 determines that the shutter button 26b is fully pressed (step S7: YES), the control unit 10 proceeds to step S8.

  Next, in step S8, the control unit 10 performs shooting. Specifically, the control unit 10 controls the shutter control unit 17 to cause the shutter drive unit 18 to open and close the shutter device 16. As a result, the image sensor 19 captures a subject image and outputs an image signal. The preprocessing unit 21 generates a digital signal from this electrical signal. Then, the control unit 10 causes the image processing unit 24 to generate image data from the digital signal, and compresses the generated image data using a JPEG (Joint Photographic Experts Group) method. Then, the control unit 10 records the compressed image data on the recording medium 29.

  After the process of step S8, the control unit 10 ends the process shown in the flowchart of FIG.

  FIG. 7 is a flowchart showing a detailed procedure of the tracking process in step S4 shown in FIG. The procedure of the tracking process in step S4 will be described using FIG. This tracking process is started after the process of step S3 or after a negative determination in step S7.

  First, in step S41, the control unit 10 determines whether or not the cross button 26a is operated by the user. Specifically, the control unit 10 monitors signals corresponding to respective operations of the left button 261a, the lower button 262a, the right button 263a, and the upper button 264a in the cross button 26a from the operation unit 26. The control unit 10 determines that the cross button 26a has been operated by the user when receiving any one of the signals corresponding to the operations of the left button 261a, the lower button 262a, the right button 263a, and the upper button 264a. On the other hand, the control unit 10 determines that the cross button 26a is not operated by the user when none of the signals corresponding to the operations of the left button 261a, the lower button 262a, the right button 263a, and the upper button 264a is received. To do. When the control unit 10 determines that the cross button 26a has not been operated (step S41: NO), the process proceeds to step S43. On the other hand, when the control unit 10 determines that the cross button 26a is fully pressed (step S41: YES), the control unit 10 proceeds to step S42.

  In step S42, the control unit 10 sets the search block S (n) according to the operation of the cross button by the user. Here, a case where the user operates the left button 261a of the cross button 26a will be described. In this case, for example, as shown in FIG. 9, the search block setting unit 30a determines that the position of the right end portion of the search block S (n) set in the current frame image F (n) in the horizontal direction is the tracking block P ( The center of the search block S (n) is designated so as to coincide with the position of the center O (n-1) of (n-1). Then, the search block setting unit 30a sets the search block S (n) for the current frame image F (n) with the designated center as the center of the search block S (n). Thereby, according to the operation of the left button 261a by the user, the center of the search block S (n) is arranged on the left side of the center O (n-1) of the tracking block in the previous frame image F (n-1). Thus, the search block S (n) is set. At this time, the control unit 10 displays the outer frame of the set search block S (n) on the current frame image F (n).

  As shown in FIG. 9, in the current frame image F (n), the subject OB1 that the user wants to track moves to the left, and the subject OB2 that the user does not want to track moves to the right. Accordingly, it is assumed that the subject OB1 and the subject OB2 intersect each other. Even in this case, when the subject OB2 is on the left side of the subject OB1 immediately before the subject OB1 and the subject OB2 cross each other, if the user operates the right button 263a of the cross button 26a, the user does not desire tracking. A search block S (n) is set at a position that does not overlap the face area of the subject OB2. Further, when the subject OB1 and the subject OB2 cross each other so that the subject OB2 is positioned on the right side of the subject OB1, if the user operates the left button 261a of the cross button 26a, as shown in FIG. The search block S (n) is set at a position that does not overlap with the face area of the subject OB2 for which tracking is not desired. As a result, the area of the face of the subject OB2 that the user does not want to track is excluded from the pattern matching target, so that erroneous tracking of the face of the subject OB2 can be prevented.

  Similarly, when the user operates the lower button 262a of the cross button 26a, the center of the search block S (n) is arranged below the center O (n-1) of the tracking block P (n-1). Thus, the search block S (n) is set for the current frame image F (n). When the user operates the right button 263a of the cross button 26a, the center of the search block S (n) is arranged on the right side of the center O (n-1) of the tracking block P (n-1). A search block S (n) is set for the current frame image F (n). When the user operates the upper button 264a of the cross button 26a, the center of the search block S (n) is arranged above the center O (n-1) of the tracking block P (n-1). A search block S (n) is set for the current frame image F (n).

  On the other hand, in step S43, the control unit 10 sets the search block so that the center of the search block matches the center of the tracking block. Specifically, the control unit 10 instructs the search block setting unit 30a to track the center of the search block S (n) and the tracking block in the previous frame image F (n−1) with respect to the current frame image F (n). The search block S (n) is set for the current frame image F (n) such that the center O (n−1) of the current frame image F (n−1) matches. At this time, the control unit 10 displays the outer frame of the set search block S (n) on the current frame image F (n).

  Now, as shown in FIG. 10, in the current frame image F (n), the subject OB1 and the subject OB2 cross each other due to the subject OB1 moving leftward and the subject OB2 moving rightward. Is assumed. In this case, if the user does not operate the cross button, the search block S (n) is set at a position overlapping the face area of the subject OB2 in the current frame image F (n). For this reason, the area of the face of the subject OB2 that the user does not want to track is subject to pattern matching, and thus the face of the subject OB2 may be mistracked.

  Next, in step S44, the control unit 10 performs a matching process. Specifically, the control unit 10 uses the tracking block P (n−1) stored in the tracking image memory 30c as a template image to the matching determination unit 30b, and sets the template image and the search block S (n). The pattern matching for calculating the correlation value E is performed. As a result, the position in the search block S (n) having the smallest correlation value E is obtained.

  Next, in step S45, the control unit 10 sets a tracking block. Specifically, the control unit 10 instructs the tracking block setting unit 30d to set the position in the search block S (n) with the smallest correlation value E to the position of the tracking block P (n) in the frame image F (n). The tracking block P (n) is set for the current frame image F (n).

  Next, in step S46, the control unit 10 updates the template image. Specifically, the control unit 10 causes the tracking block setting unit 30d to cut out the image in the tracking block P (n) set by the process of step S45 from the current frame image F (n). Then, the image data representing the clipped image is stored in the tracking image memory 30c as a template image for pattern matching performed on the next frame image F (n + 1). As a result, the template image stored in the tracking image memory 30c is updated to the latest one.

  Next, in step S47, the control unit 10 sets an AF frame. Specifically, the control unit 10 sets an AF frame having the same size as the tracking block P (n) at the same position as the tracking block P (n) in the current frame image F (n). As a result, the AF frame displayed on the frame image also follows the movement of the subject. Then, the control unit 10 displays the set AF frame on the current frame F (n) as a live view image.

  After the process of step S47, the control unit 10 ends the tracking process of step S4 and advances the process to step S5.

  As described above, the photographing apparatus 100 according to the present embodiment sets the search block in accordance with the operation of the cross button 26a by the user. For this reason, even when the first subject that the user desires to track and the second subject that the user does not want to track overlap in the frame image, the user operates the cross key 26a at this time to set the second subject. By setting a search block in a region outside the subject, erroneous tracking to the second subject can be prevented.

  Even when the second subject that the user does not want to track is moving, for example, when the user operates the cross button 26a, the search block is located in an area outside the second subject in the current frame image. Can be excluded from the pattern matching target. Thereby, even when the second subject that the user does not want to track is moving, the erroneous tracking to the second subject can be prevented.

  Further, in the photographing apparatus 100 according to the present embodiment, when the user operates the cross button 26a, the center of the search block set for the current frame image is set to the center of the tracking block in the previous frame image. If the search block is set so as to deviate in the same direction as the moving direction of the first subject, even a subject that is likely to deviate from the search block due to fast movement can be accommodated in the search block. Accordingly, even when a subject that easily moves out of the search block due to a fast movement is set as the tracking target, the possibility that the tracking of the subject fails may be reduced.

  In addition, the photographing apparatus 100 according to the present embodiment displays the outer frame of the search block set in each frame image on each frame image (live view image). Accordingly, the user can easily grasp the size of the search block on the frame image (live view image), and therefore, by operating the cross button 26a, a subject that does not require tracking can be easily detected from the search block. Can be excluded.

  Further, in the photographing apparatus 100 according to the present embodiment, since an image in the tracking block whose position matches the AF frame is focused, it is possible to prevent the user from accidentally focusing on a subject that the user does not desire to track.

(Modification)
In the imaging device 100 according to the present embodiment, the center of the search block S (n) is the user's cross button 26a with respect to the center O (n-1) of the tracking block in the previous frame image F (n-1). The search block S (n) is set so as to deviate in any of the up, down, left, and right directions according to the above operation. However, as shown in FIG. 11, the center of the search block S (n) is the center of the tracking block O (n−1) in the previous frame image F (n−1) and the cross button 26a of the user is The search block S (n) may be set so as to shift in an oblique direction according to the operation.

  When the user operates the left button 261a and the lower button 262a at the same time, the search block setting unit 30a indicates that the position of the upper right vertex of the search block S (n) is, for example, as shown in FIG. The search block S (n) may be set for the current frame F (n) so as to coincide with the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). .

  Similarly, when the user operates the lower button 262a and the right button 263a at the same time, the search block setting unit 30a displays the top left vertex of the search block S (n) as shown in FIG. 11B, for example. The search block S (n) is set for the current frame F (n) so that the position matches the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). May be.

  When the user operates the right button 263a and the upper button 264a at the same time, the search block setting unit 30a, for example, as shown in FIG. 11C, the position of the lower left vertex of the search block S (n) Is set so that the search block S (n) is set for the current frame F (n) so as to coincide with the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). Also good.

  In addition, when the user operates the upper button 264a and the left button 261a at the same time, the search block setting unit 30a, for example, as shown in FIG. 11 (d), displays the lower right vertex of the search block S (n). The search block S (n) is set for the current frame F (n) so that the position matches the position of the center O (n-1) of the tracking block in the previous frame image F (n-1). May be.

  In the photographing apparatus 100 according to the present embodiment, the position of the end according to the user's operation of the cross button 26a in S (n) is the center O (n−) of the tracking block in the previous frame image F (n−1). The search block S (n) is set so as to coincide with the position of 1). However, when the cross button 26a is operated by the user, the center of the search block S (n) and the center O (n−1) of the tracking block in the previous frame image F (n−1) in the direction corresponding to the operation. The search block S (n) may be set so as to be shifted by a predetermined distance (for example, 100 pixels).

  The above-described embodiments are merely examples of the present invention and are not intended to limit the present invention. Accordingly, all modifications that can be made to the present embodiment are included in the present invention.

  DESCRIPTION OF SYMBOLS 100 ... Imaging device, 10 ... Control part, 11 ... RAM, 12 ... ROM, 13 ... Optical lens apparatus, 14 ... Optical system control part, 15 ... Optical system drive , 16 ... shutter device, 17 ... shutter control unit, 18 ... shutter drive unit, 19 ... image sensor, 20 ... image sensor drive unit, 21 ... pre-processing unit, 22 ... Image input controller, 23 ... Image memory, 24 ... Image processing unit, 25 ... AF evaluation unit, 26 ... Operation unit, 27 ... Display control unit, 28 ... Display Part, 29 ... recording medium, 30 ... subject tracking part.

Claims (5)

Photographing means for sequentially photographing frame images of the subject;
Operation means for accepting a user operation and instructing a direction according to an operation accepted from the user among a plurality of directions;
First setting means for setting a search block at a position corresponding to the direction instructed by the operation means with respect to the frame image;
Second setting means for sequentially setting a tracking block for tracking a subject with respect to the frame image in accordance with a result of a matching process between a template image and an image of a search block set by the setting means;
An imaging apparatus comprising: The template image is
The tracking block set in the previous frame image captured in the past by the second setting means than the current frame image captured at the current time point,
The first setting means includes
The position of the search block is set with respect to the current frame image so that the position of the center of the search block is shifted in the direction instructed by the operation means with respect to the center of the tracking block set in the previous frame image. The imaging apparatus according to claim 1, wherein: Display control means for displaying an outer frame of the search block set by the first setting means on the frame image;
The imaging apparatus according to claim 1, further comprising: A focusing means for focusing on the subject;
Focusing control means for controlling the focusing means so as to focus on the subject in the tracking block;
The photographing apparatus according to claim 1, further comprising: A computer comprising imaging means for sequentially capturing frame images of a subject and operation means for accepting a user operation and instructing a direction according to an operation accepted from the user among a plurality of directions;
First setting means for setting a search block at a position corresponding to the direction instructed by the operation means with respect to the frame image;
Second setting means for sequentially setting a tracking block for tracking a subject with respect to the frame image in accordance with a result of a matching process between a template image and an image of a search block set by the setting means;
Program to function as.

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