Imaging device, control method, and program
The imaging device addresses false tracking by using a main subject setting mechanism with orientation and distance determinations to ensure accurate tracking and registration, even in crowded scenes.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- CANON KK
- Filing Date
- 2024-06-26
- Publication Date
- 2026-05-25
AI Technical Summary
Existing tracking technologies struggle with accurately selecting and registering the tracking target in crowded scenes where multiple subjects with similar orientations or temporary obstructions occur, leading to false tracking and reduced authentication accuracy.
An imaging device with a main subject setting mechanism that registers characteristic information of the main subject, allowing switching if another subject matches, and includes determinations on face orientation, focus, and distance to ensure reliable authentication and registration.
Enables accurate tracking and registration by preventing false tracking and ensuring reliable authentication, even in crowded conditions where subjects are moving and crossing paths.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an imaging device, a control method, and a program.
Background Art
[0002] In recent digital cameras, the development of tracking technology for detecting a person in an image obtained by an imaging element and continuously tracking the person has advanced. Among them, it is required to continuously track the subject intended by the imaging person even in a situation where tracking is more difficult. For example, a scene is assumed where a plurality of subjects (humans) move around in a sports competition or the like conducted by a team. In this case, there are scenes where the difficulty of tracking is high, such as when the subjects cross each other and the tracking target subject is temporarily blocked by another subject in front, resulting in "false tracking" of another subject. In such a scene, when the tracking target subject becomes unoverlapped with the front subject and can be detected again, it is required to correctly resume tracking.
[0003] In response to such needs, Patent Document 1 discloses a technique for registering the orientation of the face of the tracking target in each frame, comparing the face orientations, and determining the tracking target to prevent false tracking. Therefore, as a technique for continuously tracking a subject to be detected, a personal authentication technique for identifying an individual has been proposed. The specific aspect of this personal authentication technique is to extract the feature information possessed by each of the detected subjects, compare the extracted feature information with the reference feature information registered in advance, and perform a personal authentication determination by collating whether or not they match.
[0004] Further, as a countermeasure against false tracking using such a personal authentication technique, Patent Document 2 discloses a technique for registering feature information when the user designates a tracking target, and determining whether the tracking target is the subject designated as the tracking target by the user based on the registered information. And when it is determined that the subject is not the subject designated as the tracking target by the user, the tracking object is reset with the subject that intersects or separates from the tracking object as the tracking target.
Prior Art Documents
[0005] [Patent Document 1] Japanese Patent Publication No. 2010-243730 [Patent Document 2] Japanese Patent Publication No. 2020-96262 [Overview of the project] [Problems that the invention aims to solve]
[0006] However, in the technology disclosed in Patent Document 1, there are cases where the tracking target cannot be correctly selected if there are multiple people with the same facial orientation, or if the facial orientation changes while the tracking target is temporarily obscured by another person or the like. Furthermore, according to the technology disclosed in Patent Document 2, no consideration was given to the possibility of mistakenly registering characteristic information for a person who is mistracked in situations where multiple subjects are moving around and crossing paths.
[0007] During personal authentication, features are extracted using facial features such as eyes, nose, and mouth. Therefore, if the subject is facing sideways, only a portion of the subject's features can be detected, reducing the accuracy of personal authentication. Consequently, feature information is generally not registered in such cases. Similarly, if the subject is facing away, it is impossible to detect the subject's features, making registration impossible. In these situations, there was a possibility of mistakenly tracking another person (another subject) while registration was being postponed, potentially registering the features of the mis-tracked person. Therefore, when tracking a person using authentication registration information (feature information), it is necessary to reduce the risk of mistakenly registering the features of an unrelated person, even in situations where multiple people are moving around and crossing paths.
[0008] The present invention aims to provide an imaging device capable of tracking using reliable authentication and registration information. [Means for solving the problem]
[0009] To achieve the above objective, an imaging device according to one aspect of the present invention includes a main subject setting means for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, and is capable of switching the main subject if there is a subject among subjects other than the main subject that matches the registered characteristic information, and includes a first determination means for determining whether the registration conditions for the characteristic information of the main subject are met, and a second determination means for determining whether the distance difference between the main subject and other subjects meets the registration conditions, and if the first determination means determines that the registration conditions are met, the registration means is permitted to register the characteristic information of the main subject, and if the second determination means determines that the registration conditions are not met, the registration means is permitted to register new characteristic information as long as tracking of the main subject continues, regardless of the subsequent determination results of the first and second determination means. If the first determination means determines that the registration conditions are met, then one or more of the following conditions apply: the main subject's face is facing approximately forward; the main subject is in focus by the focusing unit that performs focusing control; and the main subject's characteristic information is not registered by the registration means. It is characterized by the following: [Effects of the Invention]
[0010] According to the present invention, it is possible to perform tracking using reliable authentication registration information. [Brief explanation of the drawing]
[0011] [Figure 1] This is a side cross-sectional view of an imaging device according to an embodiment of the present invention. [Figure 2] This is a block diagram of the control system of an imaging device according to an embodiment of the present invention. [Figure 3] This flowchart shows the processing when the main subject is set. [Figure 4] This is an explanatory diagram illustrating the operation of switching the main subject using the results of personal authentication. [Figure 5] This is a flowchart showing the authentication registration process. [Figure 6] This is a diagram illustrating the operation of the authentication registration process. [Modes for carrying out the invention]
[0012] Embodiments of the present invention will be described in detail below with reference to the drawings. However, the configurations described in the following embodiments are merely illustrative, and the scope of the present invention is not limited by the configurations described in the embodiments. Furthermore, multiple features of these embodiments may be combined in any way. In addition, the same or similar configurations are given the same reference numerals in the drawings to minimize redundant explanations.
[0013] (Figure 1: Side cross-sectional view of the imaging device) Figure 1 is a side cross-sectional view showing the configuration of a digital camera (hereinafter also simply referred to as "camera") 100 as an imaging device according to an embodiment of the present invention. Figure 2 is a block diagram showing the configuration of the control system of the camera 100 in Figure 1. The digital camera 100 is one embodiment of an imaging device, and other imaging devices may include, for example, a video camera.
[0014] As shown in Figure 1, in this embodiment, the camera 100 has a detachable interchangeable lens unit 120 attached to the front side (subject side) of the camera body 101. The lens unit 120 includes a focus lens 121 and an aperture 122 from the subject side, and is electrically connected to the camera body 101 via a mount contact part 123. The lens unit 120 makes it possible to adjust the amount of light taken into the camera body 101 and the focal position. The focus lens 121 can also be adjusted manually by the user.
[0015] (Image sensor 104: Processing unit 102) The image sensor 104, located on the inner rear side of the camera body 101, is implemented as a CCD sensor, CMOS sensor, etc., and is composed of an infrared cut filter, a low-pass filter, etc. During imaging, the image sensor 104 forms an image of the subject that has passed through the imaging optical system of the lens unit 120 on its upper surface, performs photoelectric conversion, and transmits a signal to the processing unit 102 inside the camera body 101 for generating the captured image.
[0016] (Image storage unit 107: Display unit 105: Shutter 103) The arithmetic unit 102 generates a captured image based on the signal received from the imaging device 104, stores it in the image storage unit 107, and displays it on the display unit 105 implemented by an LCD or the like provided on the outer back surface of the camera 100. Further, the shutter 103 disposed on the subject side of the imaging device 104 shields the imaging device 104 from light during non-imaging, while being opened during imaging to expose the imaging device 104. As will be described later, an operation unit 106 for the user to perform appropriate operations is provided on the upper part or the like of the camera body 101.
[0017] (Fig. 2: Block configuration diagram of the control system of the imaging device) Fig. 2 is a block configuration diagram of the control system of the camera 100 shown in Fig. 1. Next, the configuration of the control system will be described with reference to Fig. 2. The arithmetic unit 102 includes a multi-core CPU capable of parallel processing of a plurality of tasks, a RAM, and a ROM 206 also used for storing feature information for personal authentication processing described later. In addition to these, a dedicated circuit (not shown) or the like for executing specific arithmetic processing at high speed is also provided. As shown in Fig. 2, the arithmetic unit 102 has a control unit 201, a subject detection unit is a detector 213, a tracking arithmetic unit 203, a focus arithmetic unit 204, and an exposure arithmetic unit 205. By the CPU expanding and executing the program stored in the ROM 206 or the like in the RAM, various functions of the arithmetic unit 102 including the control unit 201 can be realized.
[0018] (Control unit The control unit 201 controls each part of the camera body 101 and the lens unit 120. That is, 104 to 107 described with reference to Fig. 1 are communicably connected to the control unit 201 with the required information. The control unit 201 can give a control signal to these, and conversely, the control unit 201 can also obtain various information from these.
[0019] (Subject detection unit 202: Detector 213) The subject detection unit 202 includes a detector 213, a subject authentication unit 214, and a main subject setting unit 215. The detector 213 processes an image to detect "specific areas" such as a person's face, and can obtain various information (subject detection results) such as the position, size, tilt, and certainty of the face of the person in the image. There may be cases where no "specific areas" are detected, or where multiple "specific areas" are detected.
[0020] The part detector, which detects facial features such as the eyes, nose, and mouth of a person, is included in detector 213. Any known method can be used as the detection method, such as AdaBoost or a convolutional neural network (CNN). Furthermore, the specific implementation may be a program running on a CPU, or a combination of both.
[0021] (Subject Recognition Unit 214) The subject authentication unit 214 receives the subject detection result obtained by the detector 213, extracts the "feature information" of the detected person's face, and can authenticate whether or not it is a specific individual. When performing such personal authentication, the subject detection unit 202 reads the individual's feature information that has been pre-stored (registered) in the ROM 206 and compares it with the "feature information" of the person's face extracted by the subject authentication unit 214 from the image of the subject detection result. This determines whether or not it matches a registered individual.
[0022] (Main subject setting section 215) The main subject setting unit 215 sets the target subject to be used for AF control (hereinafter referred to as the "main subject") from among the detected subjects. The main subject is set using a known calculation method based on size, position, reliability of the detection result, etc. In addition, when setting the main subject using the result of personal authentication, the main subject is set using the result of personal authentication by the subject authentication unit 214. If no subject is detected by the detector 213, it is also possible to set a "main subject area," which is the area to be used as the main subject, based on past detection results, feature quantities such as edges of the target frame, and defocus information of the subject.
[0023] (Tracking calculation unit 203: Focus calculation unit 204: Exposure calculation unit 205) The tracking calculation unit 203 performs tracking processing on the target subject area based on the detection information of the main subject. The tracking method can be any known method such as template matching that compares feature quantities between frames. The focus calculation unit 204 acquires defocus information for focusing on the main subject based on the information from the subject detection unit 202 or the tracking calculation unit 203, and calculates control values for controlling the focus lens 121. The exposure calculation unit 205 calculates control values for controlling the aperture 122, shutter 103, image sensor 104, etc., to properly expose the main subject.
[0024] The control unit 201 receives control values calculated by the exposure calculation unit 205 and the focus calculation unit 204, and controls the focus lens 121, aperture 122, shutter 103, display unit 105, etc. The display unit 105 displays the area on the screen that is the target of AF control (hereinafter referred to as the "AF frame"), and the detected subject included in the AF frame may be designated as the main subject. In addition, the operation unit 106 shown in Figure 1 is implemented with a release switch, mode dial, etc., and the control unit 201 receives imaging instructions, mode change instructions, etc. from the user via the operation unit 106. The above is the configuration of the control system of the camera 100.
[0025] (Figure 3: Flowchart showing the process when the main subject is set) Next, referring to Figure 3, the sequence of processes from setting the main subject in the main subject setting unit 215 to the AE and AF processing performed by the exposure calculation unit 205 and the focus calculation unit 204 in this embodiment will be explained. The processes shown in Figure 3 are basically executed by the subject detection unit 202.
[0026] (Step S301: Step S302) First, in step S301, the control unit 301 acquires image data generated based on the signal from the image sensor 104 and passes it to the subject detection unit 202, proceeding to step S302. In step S302, the detector 213 detects a subject based on the image data acquired in step S301, and the process proceeds to step S303. The objects to be detected are, for example, people, animals, or objects with prominent color brightness (hereinafter referred to as "object detection"), and subject information (type, position, size, confidence level, distance) of these detected objects is acquired.
[0027] (Step S303) In step S303, the main subject setting unit 215 sets the subject detected in step S302 as the main subject for AF control. In setting the main subject, the user may instruct the system to reset the main subject. For example, if the user operates the release switch on the control unit 106 to instruct AF control on a detected subject within the AF frame, the system selects the main subject from among the detected subjects within the AF frame by referring to the subject detection information acquired in step S302. Alternatively, the system may be configured to allow the user to manually specify the main subject by touching the subject displayed on the display unit 105. Furthermore, if there is no user instruction, the system determines whether to continue tracking the previous main subject or switch to another subject based on the subject information acquired in step S302.
[0028] (Step S304: Step S305) In step S304, the main subject setting unit 215 checks whether the main subject set in step S303 has switched from the previous main subject. If it determines that the main subject has switched (Yes), it proceeds to step S305. On the other hand, if it determines that the main subject is continuing (No), it proceeds to step S306. In step S305, the subject authentication unit 214 resets the registration information for personal authentication in step S308, which will be described later, and proceeds to step S306. That is, in step S305, the characteristic information, etc., is reset (cleared).
[0029] (Step S306) In step S306, the main subject setting unit 215 refers to the information registered for personal authentication for the main subject in step S308 and checks whether there are any detected subjects whose feature matching score to other detected subjects is above a threshold. The score is set so that the higher the matching of the feature amounts to other detected subjects, the higher the score. If it is determined that there are detected subjects whose score is above the threshold (Yes), the process proceeds to step S307; if it is determined that there are no detected subjects whose score is above the threshold (No), the process proceeds to step S308.
[0030] (Step S307) In step S307, the main subject setting unit 215 determines that the main subject set in step S303 was a subject that was "mistakenly tracked," and identifies a detected subject with a score above the threshold as the correct main subject. The unit then resets the main subject and proceeds to step S308.
[0031] (Figure 4: Diagram illustrating the operation of switching the main subject using the results of personal authentication: Figure 4(A)) Here, referring to Figure 4, we will explain the case where the primary subject is reset using the personal authentication result. Figure 4(A) shows the primary subject person 401 and other persons 402. "Characteristic information" for personal authentication is registered for the primary subject person 401.
[0032] (Figure 4(B):Figure 4(C)) Figure 4(B) shows a situation where the primary subject, person 401, and person 402, who is not the primary subject, are close together and overlapping, causing the camera to mistakenly track person 402. When the distance between subjects (401, 402) decreases, there is a risk of mistakenly tracking the primary subject in this way. Figure 4(C) is an explanatory diagram showing a situation where the mistaken tracking of person 402 continues, and person 401 is re-detected. Here, by extracting the feature information of person 401 and calculating an authentication score that represents the degree of match with the feature information registered in Figure 4(A), if the authentication score of person 401 exceeds the threshold, person 401 is determined to be the correct primary subject. Therefore, by resetting person 401 as the primary subject, the camera can correctly resume tracking.
[0033] (Step S308: Step S309) In step S308, the subject authentication unit 214 performs authentication registration processing for the main subject, referring to Figures 5 and 6, and proceeds to step S309. In step S309, the exposure calculation unit 205 performs AE control and the focus calculation unit 204 performs AF control for the main subject, and this process is completed.
[0034] (Figure 5: Flowchart showing the authentication registration process; Figure 6: Diagram explaining the operation of the authentication registration process) Next, the authentication registration process in S308 of Figure 3 will be explained with reference to Figures 5 and 6. Figure 5 is a flowchart showing the authentication registration process, and Figure 6 is an explanatory diagram of the operation of the authentication registration process. As mentioned above, the process shown in Figure 5 is basically executed by the subject detection unit 202.
[0035] (Step S501: Step S502) In step S501, the system checks whether the authentication registration process described later in S507 has not yet been performed on the main subject. If it has not been performed (YES), the system proceeds to S502; if it has been performed (NO), the authentication registration process is terminated. In step S502, the control unit 201 checks whether the main subject is in focus due to AF control by the focus calculation unit 204. If it is determined to be in focus (YES), the system proceeds to S503; if it is determined to be out of focus (NO), the process is terminated. Here, if the image is blurred due to lack of focus, facial features such as the eyes, nose, and mouth for authentication registration cannot be detected. Therefore, authentication registration is not performed in such cases.
[0036] (Step S503: Step S504) In step S503, the detection result of detector 213 is used. Specifically, it is checked whether the main subject is facing approximately forward. If it is not facing approximately forward (No), the process proceeds to step 504; if it is facing approximately forward (Yes), the process proceeds to step S506.
[0037] (Figure 6(A)) As shown in Figure 6(A), when a person is facing forward, facial features can be accurately detected. However, when a person is facing diagonally, to the side, or facing backward, as in person 602, some or all of the facial features cannot be detected. Therefore, feature extraction for authentication registration cannot be performed sufficiently, and facial recognition cannot be executed, or even if it is executed, the accuracy is not good, so authentication registration is not performed.
[0038] (Step S504) In step S504, it is determined whether there is a subject that has moved closer to the main subject than before. If it is determined that there is a subject that has moved closer (Yes), the process proceeds to S505. On the other hand, if it is determined that there is no such subject (No), the process ends. Here, the determination of whether there is a subject that has moved closer than before will be explained with reference to Figures 6(B) to 6(D).
[0039] (Figure 6(B):Figure 6(C)) In Figures 6(B) to 6(D), person 603 is a different person from the main subject, and person 604 represents the main subject. Distance 605 is the distance between person 603 and person 604, and threshold 606 is a threshold used to determine whether person 603 and person 604 are in close proximity, by comparing it with the distance between people 605. If the distance between people 605 is less than or equal to the threshold 606, it is determined that person 603 is in close proximity to the main subject (604).
[0040] In Figure 6(B), although person 604 is the main subject, the condition of being facing approximately directly in front is not met. Also, since the distance 605 is longer than the threshold 606, it is determined that the subject is not in close proximity. In Figure 6(C), person 604, the main subject, still does not meet the condition of being facing approximately directly in front, and since the distance 605 is less than or equal to the threshold 606, it is determined that the subject is in close proximity. Here, if the state changes in the order of Figure 6(B) to Figure 6(C) (Figure 6(B) → Figure 6(C)), the state in which person 603 is not in close proximity to the main subject (604) changes to a state in which it is in close proximity. Therefore, it is determined that the condition of "there is a subject that is closer than before" is met.
[0041] (Step S505: Step S506: Step S507) In step S505, the system transitions to the "registration abandoned state." The "registration abandoned state" is a state in which the execution of authentication registration is not permitted, and this state continues until the authentication registration information is reset in S305 in Figure 3. The state in which the execution of authentication registration is not permitted means, for example, that no new feature information is registered. In step S506, the system checks whether it is set to the "authentication abandoned state," and if it is (Yes), this process ends. On the other hand, if it is not (No), the system proceeds to S507. In step S507, feature information for personal authentication is generated by extracting feature quantities from the facial parts of the main subject and stored in memory. Note that flash memory or the like, which allows for non-volatile storage, can be used.
[0042] (Figure 6(D)) Figure 6(D) satisfies the condition that the main subject 604 is facing approximately forward, and if the state changes from Figure 6(B) to Figure 6(D) in chronological order, the conditions for authentication registration are met, and authentication registration is performed. On the other hand, if the state changes from Figure 6(B) to Figure 6(C) to Figure 6(D) in chronological order, the state transitions to "registration abandoned" at the point of Figure 6(C). Therefore, even if the condition that the main subject 604 is facing approximately forward is met in Figure 6(D), authentication registration will not be performed.
[0043] Furthermore, if it takes a long time for authentication registration to occur after tracking the main subject 604, the risk of false tracking increases even if the condition "there is a subject that is closer than the previous time" is not met. For this reason, if authentication registration has not been completed even after a predetermined amount of time has elapsed since the main subject was newly set in step S303 of Figure 3, the system may transition to a "registration abandoned state" and remain in this state until the authentication registration information is reset in step S305 of Figure 3.
[0044] As explained above, this embodiment checks multiple conditions when performing authentication registration, and if the condition "there is a subject approaching" is met, it transitions to a "registration abandoned state" and does not perform authentication registration until a new main subject is set. In this way, when there is a risk of false tracking, the tracking process can be performed accurately using reliable authentication registration information without performing authentication registration.
[0045] Furthermore, if at least one of steps S501, S502, and S503 in Figure 5 is met, the process of registering the characteristic information of the main subject being tracked may be executed in step S507.
[0046] <Variation> (1) For example, in step S306 of Figure 3, if it is determined that there is a subject whose authentication score is above the threshold, the process of switching the main subject to the authenticated subject is executed, but it is also possible to simply switch to the subject with the highest score. In addition, if there are multiple subjects with the highest score, it is also possible to switch to the subject whose face is facing most directly forward. (2) In addition, the threshold 606 for the distance 605 between the person 603 and the main subject 604 in Figures 6(B) to 6(C) may be changed instead of being fixed. For example, the control unit 201 may automatically change the threshold 606 according to the number of close-range plays in a sports competition within a predetermined time. Alternatively, the user may set it using the operation unit 106 according to the type of competition. To do this, a database may be created showing the number of times the distance 605 is less than or equal to the threshold 606 in a large number of competitions, and the threshold 606 may be determined by referring to this database.
[0047] <Addendum> This embodiment includes the following configurations, methods, and programs. (Composition 1) An imaging device comprising a main subject setting means for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, wherein if there is a subject other than the main subject that matches the registered characteristic information, the main subject can be switched. A first determination means for determining whether or not the registration conditions for the characteristic information of the main subject are met, The system includes a second determination means for determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, An imaging device characterized in that, if the first determination means determines that the registration conditions are met, the registration means is permitted to register characteristic information of the main subject, and if the second determination means determines that the registration conditions are not met, the registration means is not permitted to register new characteristic information as long as tracking of the main subject continues, regardless of the subsequent determination results of the first and second determination means. (Configuration 2) If the first determination means determines that the registration conditions are met, The imaging apparatus according to claim 1, characterized in that the orientation of the main subject's face is approximately facing forward, the main subject is in focus by a focusing unit that performs focusing control on the main subject, and the characteristic information of the main subject is not registered by the registration means. The apparatus according to configuration 1, characterized in that (Composition 3) The system further includes proximity detection means for determining whether the distance difference between the main subject and other subjects is below a threshold, The imaging apparatus according to configuration 1 or 2, characterized in that if the proximity determination means satisfies the determination condition in the previous determination but does not satisfy the determination condition in the current determination, the second determination means determines that the registration condition is not satisfied. (Composition 4) The imaging device according to configuration 1 or 2, characterized in that if the registration means fails to register feature information within a predetermined time after the main subject has been set by the main subject setting means, the registration of feature information is not permitted while tracking of the main subject continues. (Composition 5) A switching determination means for determining whether or not the main subject has been switched, The imaging device according to configuration 1 or 2, further comprising: a reset means for resetting the feature information registered in the registration means when the switching determination means determines that the main subject has been switched. (Composition 6) The imaging device according to configuration 1 or 2, further comprising a resetting means for determining that a subject with an authentication score above a threshold is the correct primary subject and resetting the primary subject if such a subject exists. (method) A control method for an imaging device comprising a main subject setting unit for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, wherein the main subject can be switched if there is a subject other than the main subject that matches the registered characteristic information, A first determination step to determine whether or not the registration conditions for the characteristic information of the main subject are met, The process includes a second determination step of determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, A control method for an imaging device, characterized in that, if the first determination step determines that the registration conditions are met, the registration of characteristic information of the main subject by the registration means is permitted, and if the second determination step determines that the registration conditions are not met, the registration of new characteristic information by the registration means is not permitted as long as tracking of the main subject continues, regardless of the determination results of the subsequent first and second determination steps. (program) A program that causes a computer to execute a control method for an imaging device that includes a main subject setting unit for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, and that can switch the main subject if there is a subject other than the main subject that matches the registered characteristic information, The control method described above is A first determination step to determine whether or not the registration conditions for the characteristic information of the main subject are met, The process includes a second determination step of determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, A program characterized in that, if the first determination step determines that the registration conditions are met, the registration means is permitted to register characteristic information of the main subject, and if the second determination step determines that the registration conditions are not met, the registration means is not permitted to register new characteristic information as long as tracking of the main subject continues, regardless of the determination results of the subsequent first and second determination steps.
[0048] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the embodiments described above, and various modifications and changes are possible within the scope of its gist. For example, the present invention can also be realized by supplying a program that implements one or more of the functions of the above embodiments to a system or device via a network or recording medium, and the processor of the computer in that system or device reads and executes the program. Furthermore, the present invention can also be realized by a circuit (e.g., an ASIC) that implements one or more functions. [Explanation of symbols]
[0049] 100 Digital Cameras (Cameras) 101 Camera body 102 Arithmetic equipment 103 Shutter 104 Image sensor 105 Display section 106 Operation section 107 Image storage unit 120 Lens Unit 121 Focus Lens 122 aperture 201 Control Unit 202 Subject detection unit 203 Tracking calculation section 204 Focus Calculation Unit 205 Exposure calculation section 206 ROM 213 Detectors 214 Subject Recognition Section 215 Main subject setting section
Claims
1. An imaging device comprising a main subject setting means for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, wherein if there is a subject other than the main subject that matches the registered characteristic information, the main subject can be switched. A first determination means for determining whether or not the registration conditions for the characteristic information of the main subject are met, The system includes a second determination means for determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, If the first determination means determines that the registration conditions are met, the registration means is permitted to register the characteristic information of the main subject. If the second determination means determines that the registration conditions are not met, the registration means is not permitted to register new characteristic information as long as tracking of the main subject continues, regardless of the subsequent determination results of the first and second determination means. If the first determination means determines that the registration conditions are met, An imaging device characterized in that the main subject's face is facing approximately forward, the main subject is in focus by a focusing unit that performs focusing control, and the main subject's characteristic information is not registered by the registration means.
2. The system further includes proximity detection means for determining whether the distance difference between the main subject and other subjects is below a threshold, The imaging apparatus according to claim 1, characterized in that if the proximity determination means determined that the determination conditions were met in the previous determination but not in the current determination, the second determination means determines that the registration conditions are not met.
3. The imaging device according to claim 1, characterized in that if the registration means fails to register feature information within a predetermined time after the main subject has been set by the main subject setting means, the registration of feature information is not permitted while tracking of the main subject continues.
4. A switching determination means for determining whether or not the main subject has been switched, The imaging apparatus according to claim 1, further comprising a reset means for resetting the feature information registered in the registration means when the switching determination means determines that the main subject has been switched.
5. The imaging apparatus according to claim 1, further comprising a resetting means for determining that a subject with an authentication score above a threshold is the correct primary subject and resetting the primary subject if such a subject exists.
6. A control method for an imaging device comprising a main subject setting unit for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, wherein the main subject can be switched if there is a subject other than the main subject that matches the registered characteristic information, A first determination step to determine whether or not the registration conditions for the characteristic information of the main subject are met, The process includes a second determination step of determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, If the first determination step determines that the registration conditions are met, the registration of characteristic information of the main subject by the registration means is permitted. If the second determination step determines that the registration conditions are not met, the registration of new characteristic information by the registration means is not permitted as long as tracking of the main subject continues, regardless of the determination results of the subsequent first and second determination steps. If the first determination step determines that the registration conditions are met, A control method for an imaging device, characterized in that the main subject's face is facing approximately forward, the main subject is in focus by a focusing unit that performs focusing control, and the main subject's characteristic information is not registered by the registration means.
7. A program that causes a computer to execute a control method for an imaging device that includes a main subject setting unit for setting a main subject to be tracked from among the detected subjects, and a registration means for registering characteristic information of the main subject, and that can switch the main subject if there is a subject other than the main subject that matches the registered characteristic information, The control method described above is A first determination step to determine whether or not the registration conditions for the characteristic information of the main subject are met, The process includes a second determination step of determining whether the distance difference between the main subject and other subjects satisfies the registration conditions, If the first determination step determines that the registration conditions are met, the registration of characteristic information of the main subject by the registration means is permitted. If the second determination step determines that the registration conditions are not met, the registration of new characteristic information by the registration means is not permitted as long as tracking of the main subject continues, regardless of the determination results of the subsequent first and second determination steps. If the first determination step determines that the registration conditions are met, A program characterized in that the main subject's face is facing approximately forward, the main subject is in focus by a focusing unit that performs focusing control on the main subject, and the main subject's characteristic information is not registered by the registration means.