JP5070856B2 - Imaging device - Google Patents

Description

  The present invention relates to an image tracking device and an imaging device.

  A frame (tracking frame) that surrounds the subject to be tracked is set in the captured image, and the image data in the tracking frame is stored as a template (reference image). An imaging device is known that searches for a high area (template matching), moves a tracking frame to that area, updates the template with image data in the new tracking frame, and tracks the subject (for example, Patent Document 1).

Prior art documents related to the invention of this application include the following.
JP 2006-058431 A

  However, the above-described conventional imaging apparatus sometimes erroneously captures a subject that is not a tracking target in the middle of template matching, and even in that case, there is a problem that the template is updated with image data of the subject that is not the tracking target.

(1) An imaging apparatus according to claim 1 corresponds to a tracking target in the first image and an imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image. A storage unit that stores an image of a portion to be processed as a first reference image, a recognition unit that recognizes an image of a portion corresponding to the first reference image in the second image as a second reference image, and the optical system. A focus detection unit that repeatedly detects the focus adjustment state of the optical system for a plurality of focus detection areas in the screen, and a selection unit that selects a focus detection area closest to a portion corresponding to the tracking target from the plurality of focus detection areas And the focus adjustment state of the focus detection area selected by the selection unit of the first image and the focus adjustment state of the focus detection area closest to the position of the second reference image of the second image A calculator for calculating an absolute value, when the absolute value of the difference calculated by the calculation unit is smaller than the determination threshold value, controlling the second reference image in the storage unit so as to be stored as the first reference image And a control unit that controls the storage unit not to store the second reference image when the absolute value of the difference is not smaller than the determination threshold.
(2) The imaging device according to claim 2 is the imaging device according to claim 1, wherein the control unit controls the storage unit to store the second reference image. A drive control unit that performs drive control of the photographing lens based on a focus adjustment state of the focus detection area that is closest to the position of the second reference image of the second image is provided.
(3) An imaging apparatus according to claim 3 corresponds to a tracking target in the first image and an imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image. A storage unit that stores an image of a portion to be processed as a first reference image, a recognition unit that recognizes an image of a portion corresponding to the first reference image in the second image as a second reference image, and the optical system. A focus detection unit that repeatedly detects the focus adjustment state of the optical system for a plurality of focus detection areas in the screen, and a selection unit that selects a focus detection area closest to a portion corresponding to the tracking target from the plurality of focus detection areas And an absolute value of a difference between a focus adjustment state of the plurality of focus detection areas of the second image and a focus adjustment state of the focus detection area selected by the selection unit of the first image is equal to or less than a predetermined value. Na When a distance between a specifying unit that specifies a focus detection area in which a focus adjustment state is obtained, a position of the focus detection area specified by the specifying unit, and a position of the second reference image is smaller than a determination threshold, Control is performed to store the second reference image as the first reference image in the storage unit, and control is performed so that the second reference image is not stored in the storage unit when the interval is not smaller than the determination threshold. And a control unit.
(4) The imaging device according to claim 4 is the imaging device according to claim 3, wherein the control unit controls the storage unit to store the second reference image. And a drive control unit that performs drive control of the photographing lens based on a focus adjustment state of the focus detection area specified by the specifying unit.
(5) An imaging apparatus according to claim 5 corresponds to an imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image, and corresponds to a tracking target in the first image. A storage unit that stores an image of a portion to be processed as a first reference image, a focus detection unit that repeatedly detects a focus adjustment state of the optical system for a plurality of focus detection areas in a screen by the optical system, and the plurality of focus detections A selection unit that selects a focus detection area that is closest to the portion corresponding to the tracking target from the area, and a focus adjustment state of the plurality of focus detection areas of the second image that is selected by the selection unit of the first image. A specifying unit that specifies a focus detection area in which a focus adjustment state in which an absolute value of a difference from the focus adjustment state of the focus detection area is equal to or less than a predetermined value is obtained; and When the recognition unit that recognizes the image of the portion corresponding to the position of the determined focus detection area as the second reference image, and the first reference image and the second reference image are more similar than the determination threshold value, The storage unit is controlled to store the second reference image as the first reference image, and when the first reference image and the second reference image are not similar to a determination threshold, the storage unit And a control unit that controls not to store the second reference image.
(6) The image pickup apparatus according to claim 6 is the image pickup apparatus according to claim 5, wherein the control unit controls the storage unit to store the second reference image. And a drive control unit that performs drive control of the photographing lens based on a focus adjustment state of the focus detection area specified by the specifying unit.
(7) The imaging device according to claim 7 is the imaging device according to any one of claims 1 to 6, wherein the focus detection unit performs focus detection by a phase difference detection method. .

  According to the present invention, an image of a portion to be tracked of an image by an optical system is stored as a reference image, and an image for recognizing the position of the tracking target based on the reference image from images repeatedly obtained by the optical system In tracking, it is possible to accurately extract an image of a portion to be tracked from images repeatedly obtained by the optical system, update the reference image, and improve the image tracking performance.

  As an embodiment of the present invention, a single lens reflex digital camera will be described as an example. Note that the imaging apparatus of the present invention is not limited to a single-lens reflex digital camera, but can be mounted on a compact digital camera, a single-lens reflex film camera, or the like.

  FIG. 1 is a block diagram showing an electric circuit of a single-lens reflex digital camera of one embodiment, and FIG. 2 is a cross-sectional view showing a mechanism of the single-lens reflex digital camera of one embodiment. In FIG. 1 and FIG. 2, illustration and description of camera devices and circuits not directly related to the present invention are omitted. The configuration of a single-lens reflex digital camera according to an embodiment will be described with reference to FIGS.

  The photometric element 1 is a photometric sensor for detecting subject luminance, and is an imaging sensor for capturing a subject image for image analysis for subject tracking. As shown in FIG. Is divided into a square lattice, and photometry is performed for each divided photometry area. In this embodiment, an example is shown in which the photometric element 1 is used both for photometry and for subject tracking, but an imaging element dedicated to subject tracking may be provided separately. The photometric element 1 is composed of a CCD, a CMOS or the like, and pixels are arranged for each divided photometric area as shown in FIG. That is, a plurality of pixels are arranged in a two-dimensional square lattice shape with eight in the X direction and six in the Y direction. Further, each pixel is divided into pixels having B, G, and R three primary color filters. The photometric circuit 2 performs signal processing such as noise removal, sensitivity correction, and A / D conversion on the photometric signal output from the photometric element 1, and outputs a BGR luminance signal for each pixel.

  The focus detection element 3 is built in the AF module 21 shown in FIG. 2, and the exit pupil plane of the photographing lens 22 is set in 11 focus detection areas set in the field indicated by “+” in FIG. A shift amount of a pair of subject images formed by a pair of light beams that have passed through the pair of regions is detected, and a focus detection signal for each focus detection area is output. FIG. 3A shows the correspondence between the divided photometry area of the photometry element 1 and the focus detection area of the focus detection element 3. The eleven focus detection areas are the range of 8 × 6 divided photometry areas. Is set in. The focus detection circuit 4 detects the defocus amount for each focus detection area by the phase difference detection method based on the focus detection signal for each focus detection area output from the focus detection element 3.

  The image pickup device 5 is composed of a CCD or a CMOS, picks up a subject image formed by the taking lens 22 and outputs an image pickup signal. The signal processing circuit 6 performs processing such as sampling, noise removal, sensitivity correction, and A / D conversion on the imaging signal output from the imaging device 5. The buffer 7 is a memory that temporarily stores image data, a defocus amount, and the like. The image processing circuit 8 performs processing such as pixel interpolation, resolution conversion, white balance control, gamma correction, matrix calculation, and image compression on the image data processed by the signal processing circuit 6. The memory card 9 is a recording medium that records captured images.

  The lens driving circuit 10 drives a focusing lens (not shown) of the photographic lens 22 according to the focus detection result, and adjusts the focus of the photographic lens 22. The aperture drive circuit 11 drives the aperture 23 according to the exposure calculation result to adjust the aperture. The shutter drive circuit 12 drives the shutter 24 according to the exposure calculation result to expose the image sensor 5. The mirror drive circuit 13 drives the main mirror 25 and the sub mirror 26 to raise and lower the mirrors 25 and 26. The display drive circuit 14 controls a diffusion type liquid crystal display (hereinafter referred to as a finder display) 15 provided on a screen 27 (see FIG. 2) of the finder optical system, and a tracking target region (referred to as a subject image on the screen 27). (Also called a tracking frame) and a focus detection area are superimposed and displayed.

  The operation switches 16 are switches that are turned on or off in accordance with the operation of various operation members for operating the camera. The operation switches 16 include a mode selector for selecting a shooting mode such as a release half-press switch that is turned on when the shutter button is half-pressed, a release full-press switch that is turned on when the shutter button is fully pressed, and a tracking shooting mode. , Direction keys for selecting a focus detection area, and the like are included.

  The control circuit 17 includes peripheral components such as a CPU 17a and a memory 17b, and is connected to the above-described camera circuits and devices via the bus 18 to perform various controls and operations of the camera. The control circuit 17 has a subject tracking function, a similarity calculation function, a distance calculation function, and the like depending on the software form of the microcomputer. Details of these functions will be described later.

  In FIG. 2, the main mirror 25 and the sub mirror 26 are placed in the optical path of the photographing lens 22 when not photographing. In this state, a part of the subject luminous flux transmitted through the photographing lens 22 is reflected by the main mirror 25 and guided to the diffusion screen 27 to form a subject image (hereinafter referred to as a finder image). This viewfinder image is guided to the photographer's eyes through a condenser lens 28, a pentaprism 29, a beam splitter 30, and an eyepiece lens 31, and a part of the viewfinder image is divided upward by the beam splitter 30 to form a diffraction grating 32 and a photometric lens 33. To the photometric element 1 via The configuration of the photometric optical system including the beam splitter 30, the diffraction grating 32, and the photometric lens 33 is not limited to the configuration of this embodiment.

  The diffraction grating 32 uses the light diffraction phenomenon to split the light flux for each wavelength. The light emitted from one point of the subject by the diffraction grating 32 is spectroscopically incident on the photometric element 1 so that light of each wavelength is incident on each RGB pixel of the photometric element 1 shown in FIG. . Thereby, false color correction can be performed, and correct color information can be detected when the subject is tracked based on the color information of the subject to be tracked.

  When not photographing, a part of the subject luminous flux is transmitted through the main mirror 25, reflected by the sub mirror 26 and guided to the AF module 21, and a pair of subject images for each focus detection area by the focus detection element 3 of the AF module 21. The amount of deviation is detected.

  At the time of photographing, the main mirror 25 and the sub mirror 26 are flipped up to the position 25 'and are retracted from the photographing optical path of the photographing lens 22. In this state, the aperture 23 is reduced to a predetermined aperture value, the shutter 24 is opened only for a predetermined shutter time, and imaging by the image sensor 5 is performed. After the shutter time elapses, the shutter 24 is closed, the main mirror 25 and the sub mirror 26 are returned to the photographing optical path, and the aperture 23 is opened.

  4 and 5 are flowcharts illustrating the tracking imaging process according to the first embodiment. The control circuit 17 executes the tracking shooting process when the tracking shooting mode is selected by the shooting mode selector included in the operation switches 16 and the release half-press switch is turned on. In step 1, the photometry element 1 and the photometry circuit 2 perform photometry of the object scene, and the photometric values R [X, Y], G [X, Y], B [X, Y] for each RGB color in each divided photometry area. (X = 1 to 8, Y = 1 to 6, see FIG. 3A) is stored in the buffer 7.

  In subsequent step 2, the focus detection element 3 and the focus detection circuit 4 detect the defocus amount D [N] (N = 1 to 11) for each focus detection area. Here, N is the number of the focus detection area, and in FIG. 3A, it is 1 to 3 from the upper left, 4 to 8 from the middle left, and 9 to 11 from the lower left. The defocus amount D [N] of the focus detection area selected by the photographer using the direction keys (not shown) of the operation switches 16 is stored in the buffer 7. For example, when the central focus detection area is selected, the defocus amount D [6] is stored.

In step 3, image data is calculated based on the photometric values R [X, Y], G [X, Y], and B [X, Y] of each divided photometric area. In this embodiment, color data and luminance data are calculated as image data, and the tracking processing is performed using the color data and luminance data as image data of a template (reference image). However, the tracking processing is performed using only color data as template image data. You may go. First, color data is obtained by the following equation.
RG [X, Y] = Log2 (R [X, Y])-Log2 (G [X, Y]),
BG [X, Y] = Log2 (B [X, Y])-Log2 (G [X, Y]) (1)
In the formula (1), X = 1 to 8, Y = 1 to 6. Next, luminance data is obtained by the following equation, where T is the charge accumulation time (exposure time) of the photometry element 1, GN is the gain of the photometry circuit 2, and Kr, Kg, Kb are the coefficients of each color.
L [X, Y] = Log2 (Kr.R [X, Y] + Kg.G [X, Y] + Kb.B [X, Y])-Log2 (T) -Log2 (GN) (2)
The calculated color data and luminance data are stored in the buffer 7.

  In step 4, the image data of the divided photometry area corresponding to the focus detection area selected by the photographer is extracted from the image data of the entire photometry screen stored in the buffer 7, and this image data is extracted from the subject to be tracked. Store in the buffer 7 as a template. In this embodiment, as shown in FIG. 3B, two pixels in the X direction (TX = 1 to 2) and two pixels in the Y direction (TY = 1 to 2) centering on the position of each focus detection area. The 2 × 2 pixel square array area is set as a tracking target area, that is, a tracking frame, and 2 × 2 pixel image data in the tracking frame is stored as a subject tracking template. For example, when the photographer selects the focus detection area N = 6, RG [X, Y], BG [X, Y], L [X, Y] (X = 4˜ 5, Y = 3 to 4), and this is extracted as template image data TRG [TX, TY], TBG [TX, TY], TL [TX, TY] (TX = 1 to 2, TY = 1 to 2). ) Is stored in the buffer 7.

  When the setting of the tracking frame and the template is completed, the process proceeds to step 5, where the photometry element 1 and the photometry circuit 2 perform photometry of the object field, and the photometric values R [X, Y], G [ X, Y] and B [X, Y] (X = 1 to 8, Y = 1 to 6) are detected and the photometric value in the buffer 7 is updated. In subsequent step 6, the defocus amount D [N] (N = 1 to 11) for each focus detection area is detected by the focus detection element 3 and the focus detection circuit 4 and stored in the buffer 7. In step 7, based on the photometric values R [X, Y], G [X, Y], B [X, Y] of each divided photometric area, the image data RG [X, Y], BG [X, Y], L [X, Y] (X = 1 to 8, Y = 1 to 6) are calculated, and the image data in the buffer 7 is updated.

  In step 8, image data RG [X, Y], BG [X, Y], L [X, Y] of the entire subject range stored in the buffer 7 in step 7 (X = 1 to 8, Y = 1 to 1). 6) Similar to the template image data TRG [TX, TY], TBG [TX, TY], TL [TX, TY] (TX = 1 to 2, TY = 1 to 2) set in step 4 Search for high-frequency areas and perform template matching. Specifically, as shown by a thick broken line in FIG. 3A, an evaluation area of a square array of 2 × 2 pixels having the same size as the tracking frame is set in the photometric screen of the photometric element 1, and this evaluation area Is set to (HX, HY). The coordinates of the evaluation area indicated by the thick broken line in FIG. 3A are HX = 3 and HY = 2.

In this evaluation area, a sum Diff [HX, HY] of absolute values of differences between the image data of the evaluation area and the image data of the template is obtained by the following equation. In this specification, Diff [HX, HY] is referred to as “residual amount”. The smaller the residual amount of image data between the evaluation area and the template, the higher the similarity between the two areas.
Diff [HX, HY] = ΣΣ {Krg · ABS (RG [HX-1 + TX, HY-1 + TY] −TRG [TX, TY]) + Kbg · ABS (BG [HX-1 + TX, HY-1 + TY] -TBG [TX, TY]) + Kl ABS (L [HX-1 + TX, HY-1 + TY] -TL [TX, TY] (3)
In the equation (3), ΣΣ represents a sum calculation of TX = 1 to 2, TY = 1 to 2, and Krg, Kbg, and Kl are coefficients that adjust the influence of each color and luminance data. While shifting the evaluation area little by little in the photometry screen, the residual amount Diff [HX, HY] is calculated by the equation (3) to obtain the position coordinates (HX, HY) of the evaluation area that minimizes the residual amount. The position is set as a new tracking target area, that is, a tracking frame.

  In Step 9, it is determined whether or not to update the template based on the subject tracking calculation result (Step 8) and the focus detection result (Step 6). First, the defocus amount of the focus detection area closest to the position coordinates (HX, HY) of the new tracking frame is read from the buffer 7 and is defined as D [near tracking coordinates]. Next, the defocus amount used for the previous focus adjustment (step 12 to be described later) is read from the buffer 7 and is defined as D [previous]. However, since focus adjustment has not yet been performed immediately after the tracking shooting process is started, the defocus amount of the photographer's selection area stored in the buffer 7 in step 2 is set to D [previous]. Then, D [near tracking coordinates] and D [previous] are compared to determine whether or not the absolute value of the difference between the two defocus amounts is equal to or less than a predetermined determination reference value. As the determination reference value, an experiment is performed according to various shooting scenes and shooting conditions, and a value that can be obtained only for the same subject is determined.

  When the absolute value of the difference between D [near tracking coordinates] and D [previous] is less than the criterion value, the color and brightness of the subject in the new tracking frame and the subject focused on the previous time are similar on the photometry screen. And the position in the depth direction of the photometry screen (direction perpendicular to the photometry screen) is also similar. Therefore, in this case, since there is a high probability that the subject in the new tracking frame is the same as the subject to be tracked initially selected by the photographer, the image data of the template is updated with the image data of the new tracking frame.

  On the other hand, if the absolute value of the difference between D [tracking coordinate vicinity] and D [previous] is larger than the determination reference value, a subject different from the previous focused subject is tracked even though the colors and brightness are similar. Therefore, the template image data is not updated. Further, even when the focus detection area does not exist in the vicinity of the position coordinates (HX, HY) of the new tracking frame, the template image data is not updated.

  If it is determined that the template needs to be updated, the process proceeds to step 10, and the template image data TRG [TX, TY], TBG [TX, TY], TL [TX, TY] in the buffer 7 is used based on the image data of the new tracking frame. (TX = 1 to 2, TY = 1 to 2) is updated. Further, in step 11, the lens driving target is updated based on D [near tracking coordinates]. In step 12, the focus of the photographic lens 22 is adjusted by the lens driving circuit 10. At this time, if the lens drive target is updated in step 11, the lens drive is performed according to the updated lens drive target. If the lens drive target is not updated, the lens drive is performed according to the previously set lens drive target. Do.

  Proceeding to step 13 in FIG. 5, the release full-pressing switch of the operation switches 16 is checked with the release full-pressing switch. If the release full-pressing operation is being performed, the process proceeds to step 15; . If the release full-press operation is not performed, it is checked in step 14 whether or not the release half-press operation is continued. If the release half-press operation is continued, the process returns to step 5 to perform the above-described processing. repeat. If neither the release full-pressing operation nor the release half-pressing operation is performed, the tracking shooting process is terminated.

  When the release full-press operation is performed, the latest photometry result (the photometry value detected in step 5) is read from the buffer 7 in step 15, and the subject brightness is detected to perform exposure calculation. Then, the aperture is adjusted by the aperture driving circuit 11 with the aperture value obtained as a result of the exposure calculation, and the shutter 24 is driven by the shutter driving circuit 12 when the shutter time is the exposure calculation result. Next, in step 16, the mirror drive circuit 13 performs mirror up and the image sensor 5 captures an image. In step 17 after imaging, the image processing circuit 8 processes the captured image and records the image in the memory card 9.

<< Tracking Processing of Second Embodiment >>
The tracking imaging process of the second embodiment in which the template update process and the lens drive target update process of the tracking imaging process of the first embodiment described above are different will be described. In the tracking imaging process of the second embodiment, only the processing contents of steps 9 to 11 in FIG. 4 showing the tracking imaging process of the first embodiment are different. The configuration shown in 1 to 3 is the same, and the description is omitted.

  In the tracking imaging process of the second embodiment, whether or not to update the template based on the subject tracking calculation result (step 8) and the focus detection result (step 6) in the template update process in step 12 is described. Determine. First, the defocus amount D [N] (N = 1 to 11) of each focus detection area detected in step 6 is read from the buffer 7. Next, the defocus amount used for the previous focus adjustment (step 12 in FIG. 4) is read from the buffer 7 and is defined as D [previous]. However, since focus adjustment has not yet been performed immediately after the tracking shooting process is started, the defocus amount of the photographer's selection area stored in the buffer 7 in step 2 is set to D [previous]. Then, a defocus amount having the smallest absolute value of the difference from D [previous] is searched from D [N] (N = 1 to 11). If the absolute value of the difference is equal to or smaller than a predetermined value, D [ This time]. The predetermined value is set to a value by which it is possible to determine that the subject indicating the two defocus amounts is in the same position in the direction perpendicular to the photometry screen.

  Next, the distance on the photometry screen between the position of D [current] and the position (HX, HY) of the new tracking frame (see step 8 in FIG. 4) is calculated. The color and brightness of the subject in the new tracking frame and the subject focused on the previous time are similar on the metering screen, and the depth direction of the metering screen (direction perpendicular to the metering screen) is also similar. become. Therefore, in this case, since there is a high probability that the subject in the new tracking frame is the same as the subject to be tracked initially selected by the photographer, the image data of the template is updated with the image data of the new tracking frame. For the above-described distance determination reference value, an experiment is performed according to various shooting scenes and shooting conditions, and a value that can be obtained only by the same subject is determined.

  On the other hand, if the distance on the photometry screen between the position of D [current] and the position of the new tracking frame (HX, HY) is larger than the determination reference value, the subject focused on the previous time and the subject of the new tracking frame are In contrast, the image data of the template is not updated because there is a high possibility that the subject is different from the subject focused on the previous time. In addition, even if the absolute value of the difference between D [N] (N = 1 to 11) and D [previous] is the smallest defocus amount, if the absolute value of the difference is larger than a predetermined value, , D [current] does not exist, and it is highly likely that the subject that is different from the subject focused on the previous time is being tracked, so that the template image data is not updated.

  If it is determined that the template needs to be updated, the process proceeds to step 10, and the template image data TRG [TX, TY], TBG [TX, TY], TL [TX, TY] in the buffer 7 is used based on the image data of the new tracking frame. (TX = 1 to 2, TY = 1 to 2) is updated. Further, in step 11, the lens drive target is updated based on D [current].

<< Tracking Processing of Third Embodiment >>
The tracking imaging process of the third embodiment in which the template update and lens drive target update processes of the tracking imaging process of the first and second embodiments described above are different will be described. In the tracking shooting process of the third embodiment, only the processing contents of steps 9 to 11 in FIG. 4 showing the tracking shooting process of the first embodiment are different. The configuration shown in 1 to 3 is the same, and the description is omitted.

  In the tracking imaging process of the third embodiment, whether or not to update the template based on the subject tracking calculation result (step 8) and the focus detection result (step 6) in the template updating process in step 12 is described. Determine. First, the defocus amount D [N] (N = 1 to 11) of each focus detection area detected in step 6 is read from the buffer 7. Next, the defocus amount used for the previous focus adjustment (step 12 in FIG. 4) is read from the buffer 7 and is defined as D [previous]. However, since focus adjustment has not yet been performed immediately after the tracking shooting process is started, the defocus amount of the photographer's selection area stored in the buffer 7 in step 2 is set to D [previous]. Then, a defocus amount having the smallest absolute value of the difference from D [previous] is searched from D [N] (N = 1 to 11). If the absolute value of the difference is equal to or smaller than a predetermined value, D [ This time]. The predetermined value is set to a value by which it is possible to determine that the subject indicating the two defocus amounts is in the same position in the direction perpendicular to the photometry screen.

  Next, in the residual amount Diff obtained in step 8, the residual amount Diff calculated in the evaluation area corresponding to the focus detection area of D [current] is defined as Diff [current focus detection point]. When this residual amount Diff [current focus detection point] is equal to or smaller than a predetermined determination reference value, the color and brightness of the subject in the evaluation area corresponding to the focus detection area of D [current] and the subject focused on the previous time. Are similar on the photometric screen, and the position of the photometric screen in the depth direction (direction perpendicular to the photometric screen) is also similar. Therefore, in this case, the subject in the evaluation area corresponding to the focus detection area of D [current] has a high probability of being the same as the subject to be tracked initially selected by the photographer. The image data of the template is updated with the image data of the evaluation area corresponding to. Note that, for the above-described residual amount determination reference value, an experiment is performed according to various shooting scenes and shooting conditions, and a value that can be obtained only by the same subject is determined.

  On the other hand, if the residual amount Diff [current focus detection point] corresponding to the focus detection area of D [current] is larger than a predetermined determination reference value, the subject focused on the previous time and the subject of the new tracking frame are determined. In contrast, the image data of the template is not updated because there is a high possibility that the subject is different from the subject focused on the previous time. In addition, even if the absolute value of the difference between D [N] (N = 1 to 11) and D [previous] is the smallest defocus amount, if the absolute value of the difference is larger than a predetermined value, , D [current] does not exist, and it is highly likely that the subject that is different from the subject focused on the previous time is being tracked, so that the template image data is not updated.

  If it is determined that the template needs to be updated, the process proceeds to step 10, and the template image data TRG [TX, TY], TBG [TX, TY], TL [TX, TY] in the buffer 7 is used based on the image data of the new tracking frame. (TX = 1 to 2, TY = 1 to 2) is updated. Further, in step 11, the lens drive target is updated based on D [current].

1 is a block diagram showing an electric circuit of a single-lens reflex digital camera of an embodiment; Cross-sectional view showing mechanism of single-lens reflex digital camera of one embodiment Diagram showing the configuration of the photometric element The flowchart which shows the tracking imaging | photography process of one Embodiment The flowchart which shows the tracking imaging | photography process of one Embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photometry element 2 Photometry circuit 3 Focus detection element 4 Focus detection circuit 7 Buffer 10 Lens drive circuit 16 Operation switches 17 Control circuit

Claims (7)

An imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image;
A storage unit for storing, as a first reference image, an image of a portion corresponding to the tracking target in the first image;
A recognition unit for recognizing a part of the second image corresponding to the first reference image as a second reference image;
A focus detection unit that repeatedly detects a focus adjustment state of the optical system for a plurality of focus detection areas in a screen by the optical system;
A selection unit that selects a focus detection area closest to a portion corresponding to the tracking target from the plurality of focus detection areas;
The absolute difference between the focus adjustment state of the focus detection area selected by the selection unit of the first image and the focus adjustment state of the focus detection area closest to the position of the second reference image of the second image A calculation unit for calculating a value;
When the absolute value of the difference calculated by the calculation unit is smaller than a determination threshold, the storage unit is controlled to store the second reference image as the first reference image, and the absolute value of the difference is An image pickup apparatus comprising: a control unit that performs control so that the second reference image is not stored in the storage unit when not smaller than a determination threshold value. The imaging apparatus according to claim 1,
When the control unit controls the storage unit to store the second reference image, based on the focus adjustment state of the focus detection area closest to the position of the second reference image of the second image. An image pickup apparatus comprising a drive control unit that performs drive control of a photographing lens. An imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image;
A storage unit for storing, as a first reference image, an image of a portion corresponding to the tracking target in the first image;
A recognition unit for recognizing a part of the second image corresponding to the first reference image as a second reference image;
A focus detection unit that repeatedly detects a focus adjustment state of the optical system for a plurality of focus detection areas in a screen by the optical system;
A selection unit that selects a focus detection area closest to a portion corresponding to the tracking target from the plurality of focus detection areas;
A focus in which an absolute value of a difference between a focus adjustment state of the plurality of focus detection areas of the second image and a focus adjustment state of the focus detection area selected by the selection unit of the first image is a predetermined value or less. A specific unit for identifying a focus detection area where an adjustment state can be obtained;
When the interval between the position of the focus detection area specified by the specifying unit and the position of the second reference image is smaller than a determination threshold value, the second reference image is stored as the first reference image in the storage unit. And a control unit that controls the storage unit not to store the second reference image when the interval is not smaller than the determination threshold value. The imaging apparatus according to claim 3,
When the control unit controls the storage unit to store the second reference image, the driving for controlling the driving of the photographing lens based on the focus adjustment state of the focus detection area specified by the specifying unit An image pickup apparatus comprising: a control unit. An imaging unit that captures a first image obtained by an optical system and a second image obtained after the first image;
A storage unit for storing, as a first reference image, an image of a portion corresponding to the tracking target in the first image;
A focus detection unit that repeatedly detects a focus adjustment state of the optical system for a plurality of focus detection areas in a screen by the optical system;
A selection unit that selects a focus detection area closest to a portion corresponding to the tracking target from the plurality of focus detection areas;
A focus in which an absolute value of a difference between a focus adjustment state of the plurality of focus detection areas of the second image and a focus adjustment state of the focus detection area selected by the selection unit of the first image is a predetermined value or less. A specific unit for identifying a focus detection area where an adjustment state can be obtained;
A recognizing unit that recognizes, as a second reference image, an image of a portion corresponding to the position of the focus detection area identified by the identifying unit in the second image;
When the first reference image and the second reference image are more similar than the determination threshold, the storage unit is controlled to store the second reference image as the first reference image, and the first reference image An image pickup apparatus comprising: a control unit that performs control so that the second reference image is not stored in the storage unit when the image and the second reference image are not similar to a determination threshold. The imaging apparatus according to claim 5,
When the control unit controls the storage unit to store the second reference image, the driving for controlling the driving of the photographing lens based on the focus adjustment state of the focus detection area specified by the specifying unit An image pickup apparatus comprising: a control unit. In the imaging device according to any one of claims 1 to 6,
The focus detection unit performs focus detection by a phase difference detection method.

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