JP2011061498A - Subject tracking device, subject tracking method, and camera - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To display an AF (Auto Focus) frame during tracking a subject concerning a subject tracking device, a subject tracking method, and a camera. <P>SOLUTION: A controller 104 detects a subject area including a tracking object in a photographing screen through the use of at least one kind of information between color information and luminance information in the photographing screen. Then, when focal adjustment is performed by defining the AF area in the subject area as an object, one AF area is selected among a plurality of AF areas included in the subject area in a case where the largeness of the subject area in the photographing screen is equal to or larger than a prescribed size. The AF area is fixed to be the AF area being the object of the focal adjustment, thereby to display the AF frame indicating the one fixed AF area. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a subject tracking device, a subject tracking method, and a camera.

  The following autofocus systems are known. This autofocus system automatically tracks a subject when shooting a moving subject, and moves and displays the focus area at the tracking position (for example, Patent Document 1).

JP 2006-58431 A

  However, in the conventional autofocus system, when the subject on the shooting screen is large, the subject overlaps a plurality of focus areas, and the displayed focus area is frequently switched in the plurality of focus areas. Could feel annoying.

The subject tracking device according to the present invention includes a detection unit that detects a candidate area including a tracking target in a shooting screen using at least one of color information and luminance information in the shooting screen, and a focus area in the candidate area. Focus adjustment means for performing focus adjustment as an object, and when the size of the candidate area is greater than or equal to a predetermined area, one focus area is selected from the focus areas included in the candidate area, and the focus adjustment object by the focus adjustment means Fixing means for fixing to the focus area, and display means for displaying one focus area fixed by the fixing means on the photographing screen.
In the present invention, the fixing means may be configured such that the size of the candidate area is equal to or greater than a predetermined value when the number of focus areas included in the candidate area is equal to or greater than a predetermined value.
The fixing means may be configured such that the size of the candidate region is equal to or greater than a predetermined value when the area of the candidate region is equal to or greater than a predetermined value.
Image information acquisition means for repeatedly acquiring image information including at least one of color information and luminance information in the shooting screen is further provided, and the detection means is based on the image information acquired by the image information acquisition means. When one focus area corresponding to the position is repeatedly detected, and the display means is after the fixing means fixes one focus area, and one focus area corresponding to the tracking target position is in the candidate area Even if one focus area corresponding to the tracking target position is different from one focus area fixed by the fixing means, one focus area fixed by the fixing means may be displayed in the shooting screen. .
The detection means repeatedly detects the candidate area based on the image information acquired by the image information acquisition means, and the fixing means takes into account one enlargement factor of the size of the candidate area detected by the detection means. The focus area may be fixed.
When it is difficult to perform focus adjustment in one focus area fixed by the fixing means, the focus adjustment means performs focus adjustment using any one focus area existing around the focus area. May be.
The size of the candidate area, which is a condition when the fixing means fixes one focus area, may be arbitrarily set by the user.
The subject tracking method according to the present invention detects a candidate area including a tracking target in a shooting screen using at least one of color information and luminance information in the shooting screen, and focuses on a focus area in the candidate area. When adjustment is performed and the size of the candidate area is greater than or equal to a predetermined size, one focus area is selected from the focus areas included in the candidate area, and is fixed to the focus area that is the target of focus adjustment. The focus area is displayed in the shooting screen.
A camera according to the present invention includes any one of the subject tracking devices described above.

  According to the present invention, the focus area can be displayed without causing the user to feel bothersome.

It is a block diagram which shows the structure of one Embodiment of a camera. It is a flowchart figure which shows the flow of a subject tracking process. It is a figure which shows the example of arrangement | positioning of AF area, and the example of a display of AF frame. It is a figure which shows the specific example in case a some AF area is contained in a to-be-photographed area | region. It is a figure which shows the specific example of the setting screen for setting the threshold value of the magnitude | size of a to-be-photographed area | region. It is a figure which shows the example of fixation of AF area.

  FIG. 1 is a block diagram illustrating a configuration of an embodiment of a camera according to the present embodiment. The camera 100 includes an operation member 101, a lens 102, an image sensor 103, a control device 104, a memory card slot 105, and a monitor 106. The operation member 101 includes various input members operated by the user, such as a power button, a release button, a zoom button, a cross key, an enter button, a play button, and a delete button.

  The lens 102 is composed of a plurality of optical lenses, but is representatively represented by one lens in FIG. The image sensor 103 is an image sensor such as a CCD or a CMOS, for example, and captures a subject image formed by the lens 102. Then, an image signal obtained by imaging is output to the control device 104.

  The control device 104 generates image data in a predetermined image format, for example, JPEG format (hereinafter referred to as “main image data”) based on the image signal input from the image sensor 103. Further, the control device 104 generates display image data, for example, thumbnail image data, based on the generated image data. The control device 104 generates an image file that includes the generated main image data and thumbnail image data, and further includes header information, and outputs the image file to the memory card slot 105. In the present embodiment, it is assumed that both the main image data and the thumbnail image data are image data expressed in the RGB color system.

  The memory card slot 105 is a slot for inserting a memory card as a storage medium, and the image file output from the control device 104 is written and recorded on the memory card. The memory card slot 105 reads an image file stored in the memory card based on an instruction from the control device 104.

  The monitor 106 is a liquid crystal monitor (rear monitor) mounted on the back surface of the camera 100, and the monitor 106 displays an image stored in a memory card, a setting menu for setting the camera 100, and the like. . Further, when the mode of the camera 100 is set to the shooting mode by the user, the control device 104 repeatedly acquires image information from the image sensor 103 and outputs display image data generated based on the image information to the monitor 106. . As a result, a through image is displayed on the monitor 106.

  The control device 104 includes a CPU, a memory, and other peripheral circuits, and controls the camera 100. Note that the memory constituting the control device 104 includes SDRAM and flash memory. The SDRAM is a volatile memory, and is used as a work memory for the CPU to develop a program when the program is executed or as a buffer memory for temporarily recording data. The flash memory is a non-volatile memory in which data of a program executed by the control device 104, various parameters read during program execution, and the like are recorded.

  The camera 100 according to the present embodiment has a subject tracking function for tracking the main subject between frames. During subject tracking, focus adjustment is performed so as to focus on the subject to be tracked. Hereinafter, the processing of the camera 100 in the present embodiment will be described with reference to the flowchart shown in FIG. The process shown in FIG. 2 is executed by the control device 104 as a program that is activated when the user presses the release button included in the operation member 101 halfway.

  In step S10, the control device 104 drives an AF (Auto Focus) lens included in the lens 102 based on a half-press operation of the release button by the user, and performs focus adjustment by a known phase difference method. Focus on the subject. Then, it progresses to step S20.

  In step S20, the control device 104 acquires luminance information and color information of the main subject in the shooting screen based on an output from a photometric sensor (not shown). Thereafter, the process proceeds to step S30, and the control device 104 detects an area (subject area) including the main subject from the shooting screen based on at least one of the luminance information and the color information of the main subject acquired in step S20. Subject tracking for the subject area is started.

  At this time, as described above, the control device 104 performs focus adjustment so as to focus on the main subject being tracked. For example, in the camera 100 of the present embodiment, as shown in FIG. 3A, 51 AF areas (focus areas) indicating the arrangement positions of AF sensors are arranged in the shooting screen. Then, the control device 104 performs focus adjustment on the AF area 3b arranged in the subject area 3a including the subject being tracked. At this time, the control device 104 lights the AF area 3b used for focus adjustment in the shooting screen and displays the AF frame 3c.

  The control device 203 continuously performs focus adjustment and display of the AF frame 3c during subject tracking. As a result, as shown in FIG. 3B, even when the subject moves within the shooting screen, the focus adjustment using the AF area 3b can be performed on the subject region 3a being tracked. The AF frame 3c can be displayed in the shooting screen.

  Thereafter, the process proceeds to step S40, and the control device 104 detects the size of the subject area 3a being tracked in the shooting screen. In the present embodiment, the control device 104 detects the size of the subject area 3a based on the number of AF areas included in the subject area 3a. For example, in the example shown in FIGS. 3A and 3B, since one AF area is included in the subject area 3a, the size of the subject area 3a in this case is detected as 1. On the other hand, as shown in FIG. 4, when nine AF areas are included in the subject area 3a, the size of the subject area 3a is detected as nine.

  Thereafter, the process proceeds to step S50, and the control device 104 determines whether or not the size of the subject area 3a in the shooting screen detected in step S40 is larger than a predetermined size set in advance. In the present embodiment, the user can set in advance the threshold value of the size of the subject area 3a used in the determination in step S50, and the control device 104 sets the size of the detected subject area 3a in advance. The determination in step S50 is performed by comparing the determined threshold value.

  For example, the user can set the size of the subject area 3a as a threshold on the setting screen as shown in FIG. 5 to any one of “narrow”, “standard”, and “wide”. When “narrow” is set, the control device 104 sets the size of the subject area 3a as the threshold value to the size of four AF areas (2 × 2). When “standard” is set, the size of the subject area 3a as the threshold is set to the size of nine AF areas (3 × 3). When “wide” is set, the size of the subject area 3a as the threshold is set to the size of 16 AF areas (4 × 4).

  If a negative determination is made in step S50, the process returns to step S40 and is repeated. On the other hand, if a positive determination is made in step S50, the process proceeds to step S60. As described above, when the size of the subject area 3a in the shooting screen is larger than a predetermined size, a plurality of AF areas are included in the subject area 3a. In this case, there is a possibility that the AF area used for the focus adjustment described above frequently switches among the plurality of AF areas. In this case, the AF frame 3c displayed in the shooting screen is frequently switched among the plurality of AF areas, and the user may feel annoyed. In addition, when the AF area is frequently switched, it is necessary to adjust the focus for the AF area after switching, which may increase the processing load.

  In camera 100 in the present embodiment, in order to solve such a problem, in step S60, control device 104 determines that the AF area used for focus adjustment is one of a plurality of AF areas included in subject area 3a. Secure to one. For example, as shown in FIG. 6, the control device 104 fixes the AF area used for focus adjustment among the nine AF areas included in the subject area 3a to the AF area 6a located in the center of the subject area 3a. Focus adjustment is performed on the AF area 6a, and an AF frame 3c is displayed on the AF area 6a. Accordingly, even when a plurality of AF areas are included in the subject area 3a, the AF frame 3c can be prevented from frequently switching, and the user can be prevented from feeling bothered. Further, it is not necessary to repeat the focus adjustment while switching the AF area, so that the processing load can be reduced.

  After the AF area is fixed in this way, when the frame is switched and the position of the subject area 3a in the shooting screen changes, the control device 104 has the AF area 6a fixed in the subject area 3a after the position change. If it is included, the fixing of the AF area 6a is continued as it is. That is, the control device 104 determines that the fixed AF area 6a is the subject area even when the position of the fixed AF area 6a is different from the position of the AF area corresponding to the subject area 3a including the tracking-symmetrical subject position. If it is included in 3a, the AF frame 3c is displayed based on the already fixed AF area 6a to adjust the focus.

  On the other hand, when the fixed AF area 6a is not included in the subject area 3a after the position is changed, the AF area is once fixed, and then based on the position of the new subject area 3a. The above-described processing is performed to fix the AF area again. Thereby, even if the position of the subject area 3a in the shooting screen changes after the AF area is fixed once, it can be switched to an appropriate AF area.

  Thereafter, the process proceeds to step S70, and the control device 104 determines whether or not the subject tracking is finished. For example, when the release button is fully pressed by the user and the shooting is instructed by the user, the control device 104 ends the subject tracking and performs the shooting process. Thus, while the image information is repeatedly input from the image sensor 103, the above-described processing can be repeatedly executed for each frame. On the other hand, if a negative determination is made in step S70, the process returns to step S10, and the above-described processing is repeated based on the subsequent luminance information and color information repeatedly output from the photometric sensor. On the other hand, if an affirmative determination is made in step S70, the process ends.

According to the present embodiment described above, the following operational effects can be obtained.
(1) The control device 104 detects the subject area 3a including the tracking target in the shooting screen using at least one of the color information and the luminance information in the shooting screen, and detects the AF area 3b in the subject area 3a. When performing focus adjustment as an object, when the size of the subject area 3a in the shooting screen is greater than or equal to a predetermined size, one AF area is selected from a plurality of AF areas included in the subject area 3a, and this is adjusted. The AF area 6a is fixed to the target AF area 6a, and an AF frame 3c indicating one fixed AF area 6a is displayed. Accordingly, even when a plurality of AF areas are included in the subject area 3a, the AF frame 3c can be prevented from frequently switching, and the user can be prevented from feeling bothered.

(2) The control device 104 determines that the size of the subject area 3a is equal to or greater than a predetermined value when the number of AF areas included in the subject area 3a is equal to or greater than a predetermined value. Thus, by specifying the size of the subject region 3a based on the number of AF areas included in the subject region 3a, the size of the subject region 3a can be specified by simple processing.

(3) The control device 104, after fixing one AF area 6a, if the fixed AF area 6a is in the subject area 3a, the position of the fixed AF area 6a and the subject of tracking symmetry Even when the position of the AF area corresponding to the subject area 3a including the position is different, the AF frame 3c is displayed based on the already fixed AF area 6a. Thus, once the AF area is fixed, the AF area can be prevented from frequently switching even when the position of the subject area 3a in the shooting screen changes.

(4) The user can arbitrarily set the number of AF areas included in the subject area 3a as a condition for determining whether or not to fix to one AF area 6a. As a result, the user can select an optimum setting value according to the shooting environment.

-Modification-
The camera of the above-described embodiment can be modified as follows.
(1) In the above-described embodiment, as shown in FIG. 3A, an example in which 51 AF areas are arranged in the shooting screen has been described. However, the number of AF areas is not limited to 51 and may be other numbers.

(2) In the above-described embodiment, the example has been described in which the control device 104 detects the size of the subject area 3a based on the number of AF areas included in the subject area 3a. However, the control device 104 may calculate the area of the subject region 3a and detect the size of the subject region 3a based on the area of the subject region 3a. In this case, in step S50 of FIG. 2, the control device 104 may determine whether or not the area of the subject region 3a is larger than a predetermined area set in advance.

(3) In the above-described embodiment, when the subject area 3a includes a plurality of AF areas, the control device 104 fixes the AF area used for focus adjustment to the AF area 6a located at the center. explained. However, the AF area 6a to be fixed is not limited to the AF area located at the center in the subject area 3a, and may be another AF area such as an AF area used for focus adjustment before fixing.

(4) In the embodiment described above, the control device 104 fixes one AF area used for focus adjustment when the size of the subject region 3a in the shooting screen is larger than a predetermined size. An example was described. However, the present invention is not limited to this, and the control device 104 may determine whether or not to fix one AF area for focus adjustment in consideration of the enlargement ratio of the subject area 3a from the previous frame. Good. For example, when a plurality of AF areas are included in the subject area 3a, the control device 104 sets the previous frame even if the size of the subject area 3a in the shooting screen is equal to or smaller than a predetermined size. If the enlargement ratio of the subject area 3a from is larger than a predetermined enlargement ratio set in advance, the AF area may be fixed to one. As a result, even when the subject area 3a suddenly increases, the AF frame 3c can be prevented from frequently switching, and the user can be prevented from feeling bothered. Further, it is not necessary to repeat the focus adjustment while switching the AF area, so that the processing load can be reduced.

(5) In the above-described embodiment, when a plurality of AF areas are included in the subject area 3a, the control device 104 sets the AF areas used for focus adjustment of the plurality of AF areas included in the subject area 3a. The example in which the focus adjustment is performed with the fixed AF area 6a as a target has been described. In this case, when it is difficult to perform focus adjustment in the fixed AF area 6a, for example, when the contrast of the image in the fixed AF area 6a is low and focus adjustment cannot be performed, Focus adjustment may be performed using an AF area other than the AF area 6a included in the subject area 3a, that is, any one AF area existing around the AF area 6a. As a result, even if it is difficult to perform focus adjustment in the fixed AF area 6a, it is possible to perform focus adjustment using other surrounding AF areas.

(6) In the above-described embodiment, the case where the present invention is applied to the camera 100 has been described. However, the present invention can also be applied to other devices having a subject tracking function, such as a mobile phone with a camera and a video camera.

  Note that the present invention is not limited to the configurations in the above-described embodiments as long as the characteristic functions of the present invention are not impaired. Moreover, it is good also as a structure which combined the above-mentioned embodiment and a some modification.

100 Camera, 101 Operation member, 102 Lens, 103 Image sensor, 104 Control device, 105 Memory card slot, 106 Monitor

Claims (9)

Detecting means for detecting a candidate area including a tracking target in the shooting screen using at least one of color information and luminance information in the shooting screen;
Focus adjusting means for performing focus adjustment on a focus area in the candidate area;
Fixing means for selecting one focus area from the focus areas included in the candidate area when the size of the candidate area is greater than or equal to a predetermined area, and fixing the focus area to a focus area that is a target of focus adjustment by the focus adjustment means When,
An object tracking device comprising: display means for displaying the one focus area fixed by the fixing means in the photographing screen. The subject tracking device according to claim 1,
The subject tracking device according to claim 1, wherein when the number of focus areas included in the candidate area is equal to or greater than a predetermined value, the size of the candidate area is equal to or greater than a predetermined value. The subject tracking device according to claim 1,
The subject tracking device according to claim 1, wherein the fixing means sets the size of the candidate area to be equal to or greater than a predetermined value when the area of the candidate area is equal to or greater than a predetermined value. In the subject tracking device according to any one of claims 1 to 3,
Image information acquisition means for repeatedly acquiring image information including at least one of color information and luminance information in the photographing screen;
The detection means repeatedly detects one focus area corresponding to the position of the tracking target based on the image information acquired by the image information acquisition means,
If the one focus area corresponding to the position of the tracking target is within the candidate area after the fixing means has fixed the one focus area, the display means is positioned at the position of the tracking target. The one focus area fixed by the fixing means is displayed in the photographing screen even if the corresponding one focus area is different from the one focus area fixed by the fixing means. Subject tracking device. The subject tracking device according to claim 4,
The detection means repeatedly detects the candidate area based on the image information acquired by the image information acquisition means,
The subject tracking device, wherein the fixing unit fixes the one focus area in consideration of an enlargement ratio of the size of the candidate area detected by the detection unit. In the subject tracking device according to any one of claims 1 to 5,
When it is difficult to perform focus adjustment in the one focus area fixed by the fixing means, the focus adjustment unit performs focus adjustment using any one focus area existing around the focus area. A subject tracking device characterized in that it performs. In the subject tracking device according to any one of claims 1 to 6,
The subject tracking device, wherein a size of the candidate area, which is a condition when the fixing unit fixes the one focus area, can be arbitrarily set by a user. Using at least one of color information and luminance information in the shooting screen to detect a candidate area including a tracking target in the shooting screen;
Perform focus adjustment on the focus area in the candidate area,
When the size of the candidate area is greater than or equal to a predetermined area, select one focus area from the focus areas included in the candidate area, and fix the focus area to the focus adjustment target,
A subject tracking method, wherein the fixed one focus area is displayed in the photographing screen.   A camera comprising the subject tracking device according to claim 1.

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