Imaging device, control method thereof, program, and storage medium

Abstract

To achieve a good focusing operation even when a distant area and a near area are mixed in a subject area.SOLUTION: An imaging apparatus comprises: subject detection means that detects a subject from an image signal obtained by an image pick-up device; determination means that determines the type of the detected subject; setting means that sets a focus detection area divided into a plurality of small areas in correspondence with the area of the detected subject; focus detection means that detects information on a focal position for each of the plurality of small areas; prediction means that predicts a focal position according to the movement in a depth direction of the subject; and selection means that selects a focal position of one small area of the plurality of small areas to be employed as the focal position of the subject according to the type of the subject and the predicted focal position.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to an imaging device that performs focus adjustment by a phase difference detection method using an output signal from an imaging element. [Background technology]

[0002] In recent years, various AF methods (autofocus methods) have been put to practical use, such as an image plane phase difference AF method and a contrast AF method using an image sensor. Furthermore, in various AF methods, a technique for identifying and focusing on a main subject area is known.

[0003] In Patent Document 1, a histogram of defocus amounts is generated for multiple AF frames, and a main frame is selected from the histogram. In Patent Document 2, multiple AF frames are generated within a subject, improving the accuracy of identifying the main subject area. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2021-176009 A [Patent Document 2] Patent No. 5761984 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Documents 1 and 2, the movement of the subject is not predicted, and the focus tracking cannot keep up with the movement of the subject. Furthermore, when back focus is achieved, if the infinity side and close-up side areas are mixed within one AF frame, the desired result may not be obtained.

[0006] The present invention has been made in view of the above-mentioned problems, and has as its object to realize a good focus adjustment operation even when far and near areas are mixed within a subject area. [Means for solving the problem]

[0007] The imaging device according to the present invention comprises: an object detection means for detecting an object from an image signal obtained by an imaging element; a discrimination means for discriminating the type of the detected object; a setting means for setting a focus detection area divided into a plurality of small areas corresponding to the area of ​​the detected object; a focus detection means for detecting information relating to a focus position for each of the plurality of small areas; and a prediction means for predicting a focus position according to a movement of the object in the depth direction. Based on a histogram of the number of the small regions corresponding to the focus position, a selection unit for selecting which of the plurality of small regions is to have its focus position adopted as the focus position of the subject, When a specific type of subject is detected by the subject detection means, the selection means sets a range of the histogram based on the focus position predicted by the prediction means, and selects, within the set range of the histogram, the focus position of which of the plurality of small regions is to be adopted as the focus position of the subject. It is characterized by: Effect of the Invention

[0008] According to the present invention, even when a far area and a near area are mixed within a subject area, it is possible to realize a good focus adjustment operation. [Brief description of the drawings]

[0009] [Figure 1] 1 is a block diagram showing the configuration of an interchangeable lens camera according to an embodiment of the present invention. [Diagram 2] 4 is a flowchart illustrating the operation of the camera. [Diagram 3] 6 is a flowchart illustrating an AF frame setting operation. [Figure 4] FIG. 1 is a diagram showing the concept of a detection area for a human face. [Diagram 5] A diagram showing the concept of detection areas for a person's eyes, face, and body. [Figure 6A] A diagram showing the concept of detection areas for an animal's eyes, face, and body. [Figure 6B] A diagram showing the concept of setting AF frames for an animal's eyes, face, and body. [Figure 7] 4 is a flowchart illustrating an AF operation. [Figure 8] 6 is a flowchart illustrating a focus detection process. [Figure 9]6 is a flowchart for explaining an AF main frame selection process. [Figure 10A] A conceptual diagram of a histogram. [Figure 10B] A conceptual diagram of a histogram. [Figure 10C] A conceptual diagram of a histogram. [Figure 11] FIG. 1 is a diagram illustrating the concept of moving object prediction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0011] <Configuration of imaging device> 1 is a block diagram showing the configuration of an interchangeable lens camera (hereinafter simply called a camera) according to an embodiment of the present invention. The camera according to this embodiment is an example of an imaging device to which the present invention is applied, and is capable of performing focus adjustment by an imaging surface phase difference detection method using an output signal from an imaging element that captures a subject image.

[0012] The camera 1 is composed of a lens device (interchangeable lens) 100 and a camera body 200. The lens device 100 is attached to the camera body 200 via a mount unit (not shown) having an electrical contact unit 106. When the lens device 100 is attached to the camera body 200, a lens controller 105 that controls the overall operation of the lens device 100 and a system control unit 209 that controls the overall operation of the camera 1 become able to communicate with each other via the electrical contact unit 106.

[0013] First, a description will be given of the configuration of the lens device 100. The lens device 100 includes a photographing lens 101 including a zoom mechanism, an aperture and shutter 102 for controlling the amount of light, a focus lens 103 for focusing on an image sensor 201, a motor 104 for driving the focus lens 103, and a lens controller 105.

[0014] Next, the configuration of the camera body 200 will be described. The camera body 200 is configured to obtain an imaging signal (image signal) from a light beam that has passed through the imaging optical system of the lens device 100. The camera body 200 includes an imaging element 201 that converts reflected light from a subject into an electric signal, an A / D conversion unit 202 including a CDS circuit that removes output noise from the imaging element 201 and a nonlinear amplifier circuit that performs A / D conversion before the A / D conversion, an image processing unit 203, and an AF (autofocus) signal processing unit 204. The camera body 200 also includes a format conversion unit 205, a high-speed built-in memory (for example, a random access memory, hereinafter referred to as DRAM) 206, and an image recording unit 207 consisting of a recording medium such as a memory card and its interface. The camera body 200 also includes a timing generator 208, a system control unit 209 that controls the entire camera 1, a lens communication unit 210 that communicates between the camera body 200 and the lens device 100, a subject detection unit 211, and an image display memory (hereinafter referred to as VRAM) 212. The system control unit 209 controls the entire camera 1 by executing a program stored in a non-volatile memory (hereinafter, referred to as ROM) 219 .

[0015] Camera body 200 also has an image display unit 213 that displays images, as well as displays for operational assistance, camera status, and the shooting screen and focus detection area during shooting. It also has an operation unit 214 for externally operating camera body 200, a shooting mode switch 215 for selecting a shooting mode such as macro mode or sports mode, and a main switch 216 for powering on camera 1.

[0016] In addition, the camera is provided with a switch (hereinafter referred to as SW1) 217 ​​that is turned on when the release button is pressed halfway to perform shooting standby operations such as AF (autofocus, automatic focus adjustment) and AE (automatic exposure control), and a shooting switch (hereinafter referred to as SW2) 218 ​​that is turned on when the release button is pressed all the way to perform shooting after operating SW1.

[0017] DRAM 206 is used, for example, as a high-speed buffer for temporarily storing images, or as a working memory for compressing and expanding images. Operation unit 214 includes, for example, the following: a menu switch for configuring various settings such as the shooting function settings of camera 1 and settings for image playback, and an operation mode changeover switch for switching between shooting mode, playback mode, etc.

[0018] The image sensor 201 is composed of a CCD or CMOS sensor. Each pixel of the image sensor 201 used in this embodiment is composed of two (a pair) photodiodes A and B, and one microlens provided for the pair of photodiodes A and B. Each pixel splits incident light with the microlens to form a pair of optical images on the pair of photodiodes A and B, and outputs a pair of pixel signals (A signal and B signal) used as an AF signal described later from the pair of photodiodes A and B. In addition, an image signal (image signal, A+B signal) can be obtained by adding the outputs of the pair of photodiodes A and B.

[0019] A pair of image signals is obtained as an AF signal (in other words, a focus detection signal) used for AF by an image plane phase difference detection method (hereinafter referred to as image plane phase difference AF) by respectively combining a plurality of A signals and a plurality of B signals output from a plurality of pixels. The AF signal processor 204 performs a correlation operation on the pair of image signals to calculate a phase difference (hereinafter referred to as an image shift amount) which is the amount of shift between the pair of image signals, and further calculates a defocus amount (and a defocus direction and reliability) of the photographing optical system from the image shift amount. The AF signal processor 204 calculates the defocus amount for each of a plurality of specified regions.

[0020] <Operation of the imaging device> The operation of the imaging device according to the present embodiment will be described below with reference to FIG. 2.

[0021] FIG. 2 is a flowchart showing the flow of imaging control processing when taking a still image from a state where a live view image is being displayed. The operations of this flowchart are realized by the system control unit 209 as a computer executing a program stored in the ROM 219. The same applies to the flowcharts described hereinafter.

[0022] First, in step S201, the system control unit 209 checks the state of SW1 (217). If SW1 (217) is ON, the system control unit 209 proceeds to step S202; otherwise, it waits as it is.

[0023] In step S202, the system control unit 209 performs an AF frame setting, which will be described later, on the AF signal processing unit 204.

[0024] In step S203, the system control unit 209 performs an AF operation, which will be described later.

[0025] In step S204, the system control unit 209 checks the state of SW1 (217). If SW1 (217) is ON, the system control unit 209 proceeds to step S205; otherwise, it returns the process to step S201.

[0026] In step S205, the system control unit 209 checks the state of SW2 (218). If SW2 (218) is ON, the system control unit 209 proceeds to step S206; otherwise, it returns the process to step S204.

[0027] In step S206, after performing the shooting operation, the system control unit 209 returns the process to step S201.

[0028] <AF frame setting> FIG. 3 is a flowchart illustrating the AF frame setting process in step S202 of FIG.

[0029] First, in step S301, the system control unit 209 acquires subject detection information obtained by the subject detection unit 211. In this embodiment, the subject is detected, and the type of the subject is determined, such as whether the subject is a person or an animal such as a dog or a wild bird, and further a main area within the subject is detected. Here, the main area is the pupil, face, and body of a person or animal. These detections are performed by a known learning method using machine learning or a recognition process using an image processing means.

[0030] For example, there are several types of machine learning: (1) Support Vector Machine (2) Convolutional Neural Network (3) Recurrent Neural Network As an example of the recognition process, a method is known in which a skin color area is extracted from the gradation color of each pixel represented by image data, and a face is detected based on the degree of matching with a face outline plate prepared in advance. Another known method is to use a well-known pattern recognition technique to extract facial feature points such as the eyes, nose, and mouth to perform face detection. Note that the main area detection method applicable to the present invention is not limited to these methods, and other methods may be used.

[0031] In step S302, the system control unit 209 determines whether or not multiple main regions have been detected in the detection result of the subject detection unit 211. If multiple main regions have been detected, the system control unit 209 proceeds to step S303, and if not, the system control unit 209 proceeds to step S306.

[0032] Here, the detection concept when a single main region is detected and when multiple main regions are detected will be described with reference to FIGS.

[0033] Fig. 4(a) shows a state in which only face a has been detected, and Fig. 5(a) shows a state in which pupil A, face B, and body C have been detected. It is assumed that the type of subject, such as a person or an animal, and the center coordinates, horizontal size, and vertical size of each detected main area can be acquired from the subject detection unit 211.

[0034] In step S303, the system control unit 209 inputs the smaller of the horizontal and vertical sizes of the detected smallest main area, that is, pupil A in FIG. 5A, to MinA, and sets MinA as one AF frame size.

[0035] In step S304, the system control unit 209 calculates the horizontal size H in FIG. 5(b) that encompasses all of the main areas from the horizontal coordinates and horizontal size of each detected main area, and determines the number of horizontal AF frames by dividing H by the AF frame size MinA.

[0036] 5B that encompasses all of the main areas from the vertical coordinates and vertical sizes of each detected main area, and determines the number of vertical AF frames by dividing V by the AF frame size MinA. Then, setting of the AF frames (small areas for detecting focus) is completed.

[0037] The control flow for animals is the same as for people, and the concepts of detection area and AF frame setting are shown in Figures 6A and 6B, respectively. In this embodiment, a square area with one side of the minimum size is set as the AF frame, but the AF frame size may be different in the horizontal and vertical directions, and AF frames may be set up to the number that can be calculated by the system control unit 209.

[0038] In step S306, the system control unit 209 sets an AF frame of a predetermined size X for the detected face, as shown in Fig. 4(b). A pupil size estimated from the face may be set for this X, or a frame size may be set that ensures an S / N ratio and provides sufficient focusing performance in consideration of low-illumination environments. In this embodiment, the estimated pupil size is set to X.

[0039] In step S307, the system control unit 209 sets the number of AF frames Y such that the area of face a can be included in the AF frame size set in step S306 and the system can cope even when the face moves.

[0040] <AF operation> FIG. 7 is a flowchart for explaining the AF operation in step S203.

[0041] First, in step S401, the system control unit 209 performs focus detection processing in each AF frame and detects the defocus amount and reliability. The focus detection processing will be described later.

[0042] In step S402, the system control unit 209 performs AF main frame selection, which will be described later, using the reliability obtained in step S401.

[0043] In step S403, the system control unit 209 performs motion prediction using the defocus amount of the AF main frame selected in step S402 and the defocus history of the AF main frame selected in the past. Details will be described with reference to FIG. 11.

[0044] In step S404, the system control unit 209 drives the lens according to the prediction result calculated in step S403.

[0045] <Focus detection processing> The focus detection processing in step S401 in FIG. 7 will be described with reference to FIG. 8.

[0046] First, in step S501, the system control unit 209 sets a focus detection area in an arbitrary range within the image data output from the imaging device 201 and proceeds to step S502.

[0047] In step S502, the system control unit 209 acquires a pair of image signals (A image, B image) for focus detection from the imaging device 201 corresponding to the focus detection area set in step S501.

[0048] In step S503, the system control unit 209 performs an addition average process of horizontal line signals on the pair of signals acquired in step S502. By this process, the influence of noise on the image signal can be reduced.

[0049] In step S504, the system control unit 209 performs a filtering process to extract a signal component in a predetermined frequency band from the signals that have been averaged vertically in step S503.

[0050] In step S505, the system control unit 209 calculates a correlation amount from the signals obtained by performing the filtering process in step S504.

[0051] In step S506, the system control unit 209 calculates a correlation change amount from the correlation amount calculated in step S505.

[0052] In step S507, the system control unit 209 calculates an image shift amount from the correlation change amount calculated in step S506.

[0053] In step S508, the system control unit 209 calculates a reliability factor indicating how reliable the image shift amount calculated in step S507 is.

[0054] In step S509, the system control unit 209 converts the image shift amount into a defocus amount and ends the focus detection process.

[0055] <AF Main Frame Selection> FIG. 9 is a flowchart for explaining the main frame selection process in step S402 of FIG. 7.

[0056] In this embodiment, an example will be described in which a bird with a large distance difference among subjects is focused on. In this embodiment, the relationship between the subject distance and the number of AF frames corresponding to that subject distance is obtained. Specifically, a histogram is created with the subject position (position in the depth direction, subject distance) on the horizontal axis and the number of AF frames having defocus results corresponding to the subject position on the vertical axis. This concept is shown in FIG. 10A. The solid line indicates the position of the bird's face, and the dotted area is the AF frame. Note that the fact that the subject is a bird is detected by the subject detection unit 211 as described above.

[0057] First, in step S601, the system control unit 209 checks whether main frame selection prioritizing a predetermined direction is applicable. The conditions here are whether the type is a bird, whether there is movement in the in-plane direction of the screen or in the distance direction (depth direction), and whether the subject distance is such that the focus difference within the subject is not too large (the focus difference within the subject is smaller than a predetermined value). This is to remove only the AF frame containing the background component and to prevent the wing tip from being erroneously focused. Note that whether the subject is moving or not is determined by detecting a time-series change in the focus position of the subject and predicting the focus position of the subject, as shown in FIG. 11. Also, whether the subject distance is such that the focus difference within the subject is not too large is determined by detecting whether the subject is at a distance farther than a predetermined distance and therefore has a deep depth.

[0058] When the entire AF frame area (hereinafter referred to as the AF area) is set in the previous frame, the AF area is likely to deviate from the subject in the current frame, so panning information from the photographer may be included in the determination in step S601.

[0059] If the conditions are not satisfied in step S601, system control unit 209 advances the process to step S602, and if the conditions are satisfied, system control unit 209 advances the process to step S603.

[0060] In step S602, the system control unit 209 executes normal main frame selection. In normal main frame selection, the AF frame closest to the center of the detected subject is used. However, if the defocus amount of the AF frame at the center of the detected subject is significantly different from the predicted value (deviated by a predetermined amount or more), the AF frame closest to the prediction within the detected subject area is used.

[0061] In step S603, the system control unit 209 determines whether or not it is immediately after the start of subject detection. If it is immediately after the start of subject detection, the system control unit 209 proceeds to step S604, and if not, proceeds to step S605.

[0062] In step S604 and subsequent steps, a histogram is generated by taking the subject distance on the horizontal axis and the number of AF frames calculated for the defocus results within the same bin (one section) on the horizontal axis.

[0063] In step S604, the system control unit 209 sets a histogram generation range A. In step S605, the system control unit 209 sets a histogram generation range B. The center of the histogram generation range is set to a predicted position at the current time calculated from the result of the AF frame selected in the previous frame.

[0064] Here, the relationship between A and B is A>B. A is set wide in order to take into account the case where the focus is mistakenly set on an area other than the subject (such as the background) before the subject is detected.

[0065] In step S606, system control unit 209 determines whether the value obtained by dividing the width of the histogram generation range by the maximum number of bins is greater than C. If the value is greater than C, system control unit 209 proceeds to step S607, and if the value is equal to or less than C, system control unit 209 proceeds to step S608.

[0066] In step S607, the system control unit 209 sets the histogram bin width to a value obtained by dividing the histogram generation width by the maximum set number of bins. Also, the total number of bins is set to the maximum number. The maximum number of bins is set to the number at which main areas such as the face and eyes in the subject area can be extracted with the set bin width.

[0067] As an example, Fig. 10B shows the concept when the maximum number of bins is set to 30. In this example, the bin width is set equal to the depth of field, and the histogram generation range is set to 30 depths.

[0068] In step S608, the system control unit 209 sets the bin width to C. The total number of bins is set to a value obtained by dividing the histogram generation width by the bin width. This is because step S608 is performed when subject detection is continuing, and areas other than the subject are excluded as much as possible to prevent erroneous focus tracking on another subject or the background.

[0069] In step S609, the system control unit 209 uses the conditions set in step S608 or earlier to create a histogram based on the defocus amount of each AF frame.

[0070] In step S610, the system control unit 209 selects the closest bin that exceeds the threshold from the peak of the histogram in the created histogram. In this case, as shown in Fig. 10A, a histogram threshold is set for the number of AF frames that form the peak and the bin to be selected. Also, as shown in Fig. 10B and Fig. 10C, the threshold may be changed depending on the processing.

[0071] In step S611, system control unit 209 determines whether or not bin was successfully selected. If bin was successfully selected, system control unit 209 proceeds to step S612, and if bin was not successfully selected, system control unit 209 proceeds to step S613.

[0072] In step 612, the system control unit 209 selects an AF frame that is closest to the center of the subject detected in the bin as the main frame. In FIG. 10A, this is the AF frame indicated by the hatched portion.

[0073] In step S613, the system control unit 209 determines whether or not the in-focus position of the subject has been predicted. If the system control unit 209 has predicted the in-focus position, the process proceeds to step S614. If the system control unit 209 has not predicted the in-focus position, the process proceeds to step S615.

[0074] In step S614, the system control unit 209 selects, as the main frame, the AF frame that is closest to the prediction within the detected subject area.

[0075] In step S615, the system control unit 209 selects the closest AF frame in the selected closest bin as the main frame. By controlling in this way, it becomes possible to easily focus on the eyes and face, which are the main parts of the bird.

[0076] <Motion prediction processing> Fig. 11 is a diagram showing changes in image plane position in moving object prediction processing. In Fig. 11, the vertical axis indicates the subject image plane position calculated from the defocus amount calculated in step S401, and the horizontal axis indicates time. Also, the larger the image plane position on the vertical axis, the farther the distance is, and the history in the figure shows the state of tracking a subject approaching the photographer (camera).

[0077] The focus adjustment process is performed periodically, and T1 to T5 indicate the time when the focus adjustment process is performed. The predicted drive amount is obtained by, for example, deriving a prediction curve by a collective least squares method using past image plane positions and each focus detection time, and calculating the image plane position at the predicted destination time based on this curve. In other words, the lens is driven at time T4, and the lens is driven by an amount equivalent to the defocus amount y, aiming to be in focus at time T5.

[0078] The disclosure of this specification includes the following imaging device, method, program, and storage medium.

[0079] (Item 1) a subject detection means for detecting a subject from an image signal obtained by the imaging element; A discrimination means for discriminating a type of a detected subject; a setting means for setting a focus detection area divided into a plurality of small areas in correspondence with the area of ​​the detected subject; a focus detection unit for detecting information regarding a focus position for each of the plurality of small regions; a prediction means for predicting a focus position according to a movement of the subject in a depth direction; a selection means for selecting which of the plurality of small regions should have its focus position adopted as the focus position of the object in accordance with the type of the object and the predicted focus position; An imaging device comprising:

[0080] (Item 2) 2. The imaging device according to item 1, characterized in that, when a specific condition is not satisfied, the selection means adopts the focus position of the small area that is closest to the center of the detected subject area as the focus position of the subject.

[0081] (Item 3) The imaging device described in item 2, characterized in that when the defocus amount of the small region at the center of the subject region deviates from the predicted value by a predetermined amount or more, the selection means adopts the focus position of the small region within the detected subject region that shows a defocus amount closest to the predicted value as the focus position of the subject.

[0082] (Item 4) The imaging device described in any one of items 1 to 3, characterized in that when the type of the subject and the predicted focus position satisfy a specific condition, the selection means selects which of the multiple small regions has its focus position to be adopted as the focus position of the subject based on a histogram of the number of the multiple small regions corresponding to the focus position.

[0083] (Item 5) 5. The imaging device according to item 4, characterized in that the selection means adopts, based on the histogram, a focus position of a small region close to a center of the subject in a bin in which the number of the plurality of small regions exceeds a threshold value, as the focus position of the subject.

[0084] (Item 6) 5. The imaging device according to item 4, wherein when a predicted position of the subject in the depth direction has been detected, the selection means adopts a focus position of the small region closest to the predicted position as the focus position of the subject.

[0085] (Item 7) 5. The imaging device according to item 4, wherein the selection means adopts the focus position of the small region indicating the closest focus position in the histogram as the focus position of the subject when the predicted position of the subject in the depth direction has not been detected.

[0086] (Item 8) 8. The imaging device according to any one of items 2 to 7, wherein the specific condition is that the subject is a bird.

[0087] (Item 9) 9. The imaging device according to any one of items 2 to 8, wherein the specific condition is a condition in which the subject is moving.

[0088] (Item 10) 10. The imaging apparatus according to any one of items 2 to 9, wherein the specific condition is a subject distance at which a focus difference within the subject becomes smaller than a predetermined value.

[0089] (Item 11) 11. The imaging apparatus according to any one of items 2 to 10, wherein the specific condition is a case where a photographer is panning.

[0090] (Item 12) 12. The imaging device according to any one of items 1 to 11, wherein the subject detection means detects a main part of the subject.

[0091] (Item 13) a subject detection step of detecting a subject from an image signal obtained by the imaging element; a discrimination step of discriminating a type of the detected subject; a setting step of setting a focus detection area divided into a plurality of small areas in correspondence with the area of ​​the detected subject; a focus detection step of detecting information regarding a focus position for each of the plurality of small regions; a prediction step of predicting a focus position according to a movement of the subject in a depth direction; a selection step of selecting, according to the type of the object and the predicted focus position, which of the plurality of small areas should have its focus position adopted as the focus position of the object; 13. A method for controlling an imaging apparatus comprising:

[0092] (Item 14) Item 14. A program for causing a computer to execute each step of the control method according to item 13.

[0093] (Item 15) A computer-readable storage medium storing a program for causing a computer to execute each step of the control method described in item 13.

[0094] (Other embodiments) The present invention can also be realized by a process in which a program for realizing one or more functions of the above-mentioned embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. The present invention can also be realized by a circuit (e.g., ASIC) for realizing one or more functions.

[0095] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0096] 1: camera, 100: lens device, 103: focus lens, 105: lens controller, 200: camera body, 201: image sensor, 204: AF signal processing unit, 209: system control unit, 210: lens communication unit, 211: subject detection unit

Claims

1. a subject detection means for detecting a subject from an image signal obtained by the imaging element; A discrimination means for discriminating a type of a detected subject; a setting means for setting a focus detection area divided into a plurality of small areas in correspondence with the area of ​​the detected subject; a focus detection unit for detecting information regarding a focus position for each of the plurality of small regions; a prediction means for predicting a focus position according to a movement of the subject in a depth direction; a selection means for selecting which of the plurality of small regions should have its focus position adopted as the focus position of the subject, based on a histogram of the number of the plurality of small regions corresponding to the focus positions; Equipped with an imaging device characterized in that, when a specific type of subject is detected by the subject detection means, the selection means sets a range of the histogram based on the focus position predicted by the prediction means, and selects, within the set histogram range, the focus position of which of the plurality of small regions is to be adopted as the focus position of the subject.

2. 2. The imaging device according to claim 1, wherein the selection means adopts, based on the histogram, a focus position of a small area close to a center of the subject in a bin in which the number of the plurality of small areas exceeds a threshold value, as the focus position of the subject.

3. 3. The imaging device according to claim 2, characterized in that when the selection means is unable to select a bin in which the number of the plurality of small regions exceeds a threshold based on the histogram and a predicted position of the subject in the depth direction has been detected, the selection means adopts a focus position of the small region closest to the predicted position as the focus position of the subject.

4. 3. The imaging device according to claim 2, characterized in that when the selection means is unable to select a bin in which the number of the plurality of small regions exceeds a threshold based on the histogram and a predicted position of the subject in the depth direction has not been detected, the selection means adopts the focus position of the small region indicating the closest focus position in the histogram as the focus position of the subject.

5. 2. The imaging apparatus according to claim 1, wherein the specific type of subject is a bird.

6. The imaging device described in Claim 1, characterized in that when a specific type of subject is detected by the subject detection means and there is movement of the subject, the selection means sets the range of the histogram based on the focus position predicted by the prediction means, and selects which of the multiple small regions within the set histogram range has its focus position adopted as the focus position of the subject.

7. The imaging device described in Claim 1, characterized in that when a specific type of subject is detected by the subject detection means and the subject distance is such that the focus difference within the subject is smaller than a predetermined value, the selection means sets a range of the histogram based on the focus position predicted by the prediction means, and selects, within the set histogram range, the focus position of which of the multiple small regions is to be adopted as the focus position of the subject.

8. The imaging device described in Claim 1, characterized in that when a specific type of subject is detected by the subject detection means and the photographer is panning, the selection means sets the range of the histogram based on the focus position predicted by the prediction means, and selects which of the multiple small regions within the set histogram range has its focus position adopted as the focus position of the subject.

9. 2. The imaging apparatus according to claim 1, wherein said subject detection means detects a main portion of the subject.

10. a subject detection step of detecting a subject from an image signal obtained by the imaging element; a discrimination step of discriminating a type of the detected subject; a setting step of setting a focus detection area divided into a plurality of small areas in correspondence with the area of ​​the detected subject; a focus detection step of detecting information regarding a focus position for each of the plurality of small regions; a prediction step of predicting a focus position according to a movement of the subject in a depth direction; a selection step of selecting, based on a histogram of the number of the plurality of small regions corresponding to focus positions, which of the plurality of small regions should have its focus position adopted as the focus position of the subject; having A control method for an imaging device, characterized in that, in the selection process, when a specific type of subject is detected by the subject detection process, a range of the histogram is set based on the focus position predicted by the prediction process, and a focus position of which of the multiple small regions is to be adopted as the focus position of the subject within the set histogram range is selected.

11. A program for causing a computer to execute each step of the control method according to claim 10.

12. A computer-readable storage medium storing a program for causing a computer to execute each step of the control method according to claim 10.

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