JP2009225248A - Imaging apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a means capable of accurately tracking a subject to be tracked, with a relatively small load, even when tilting of an imaging apparatus is changed with respect to the optical axis of an imaging optical system. <P>SOLUTION: An imaging apparatus comprises an imaging unit, a memory, an attitude sensor, a control unit, and a subject tracking unit. The imaging unit picks up a subject image within a photographing screen via an imaging optical system. The memory stores a template indicating features of a tracking object. The attitude sensor detects tilting of the photographing screen with the optical axis of the imaging optical system as a rotation center. The control unit adjusts the direction of the template so as to enlarge the rotation amount of the template with respect to the photographing screen in accordance with the magnitude of a change in tilting of the photographing screen. The subject tracking unit uses the adjusted template to continuously detect the subject to be tracked from the photographing screen. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus having a subject tracking function.

Conventionally, in order to perform focus adjustment, calculation of exposure conditions, and the like following a moving main subject, various imaging devices having a subject tracking function by template matching have been proposed. It has also been proposed to extract a feature portion of interest in each image and to use a movement vector amount obtained from the feature portion of each image when aligning two images with rotational movement (an example) Patent Document 1).
Japanese Patent Laid-Open No. 11-112869

  By the way, in the conventional imaging device, there is room for improvement in that the accuracy of subject tracking can be greatly reduced if the inclination of the imaging device with respect to the optical axis changes during subject tracking. On the other hand, if matching is performed a plurality of times at the same location using a plurality of templates having different rotation angles, the responsiveness of the imaging apparatus is greatly impaired due to an increase in calculation load.

  Accordingly, an object of the present invention is to provide means capable of accurately tracking a subject to be tracked with a relatively small load even when the inclination of the imaging device changes with respect to the optical axis of the imaging optical system.

  An imaging apparatus according to one aspect includes an imaging unit, a memory, a posture sensor, a control unit, and a subject tracking unit. The imaging unit captures a subject image in the shooting screen via the imaging optical system. The memory stores a template indicating the characteristics of the tracking target. The attitude sensor detects the tilt of the shooting screen with the optical axis of the imaging optical system as the center of rotation. The control unit adjusts the orientation of the template so that the amount of rotation of the template with respect to the shooting screen increases according to the magnitude of the change in the tilt of the shooting screen. The subject tracking unit uses the adjusted template to continuously detect the tracking target subject from the shooting screen.

  In the one aspect described above, the attitude sensor may be an acceleration sensor that can detect the inclination of the optical axis of the imaging optical system with respect to the direction of gravity.

  In the one aspect described above, the control unit may update the template based on the output of the imaging unit at the time of detection when the subject to be tracked can be detected using the adjusted template.

  The imaging apparatus according to one aspect adjusts the orientation of the template so that the amount of rotation of the template with respect to the imaging screen increases in accordance with the change in the inclination of the imaging screen detected by the orientation sensor. Therefore, even when the inclination of the imaging apparatus changes with respect to the optical axis of the imaging optical system, the subject to be tracked can be accurately tracked with a relatively small load.

<Description of One Embodiment>
FIG. 1 is a block diagram illustrating a schematic configuration of an electronic camera according to an embodiment. The electronic camera of one embodiment has a subject tracking function for continuously detecting a subject to be tracked from a plurality of images acquired in time series. In one embodiment, a subject tracking function is implemented in an electronic camera as a function of an arbitrary shooting mode (for example, a kids mode suitable for child shooting).

  The electronic camera includes an imaging optical system 11, a lens driving unit 12, an imaging element 13, an AFE 14, an attitude sensor 15, a CPU 16, a first memory 17 and a second memory 18, and a recording I / F (interface). 19, a monitor 20, a release button 21 and an operation member 22. Here, each component described above is stored in the housing 23. The lens driving unit 12, the AFE 14, the attitude sensor 15, the first memory 17 and the second memory 18, the recording I / F 19, the monitor 20, the release button 21, and the operation member 22 are connected to the CPU 16, respectively.

  The imaging optical system 11 includes a plurality of lens groups including a zoom lens and a focusing lens. The lens position of the focusing lens is adjusted by the lens driving unit 12 in the optical axis direction. For simplicity, the imaging optical system 11 is illustrated as a single lens in FIG.

  The image sensor 13 photoelectrically converts the subject image in the shooting screen based on the light beam that has passed through the imaging optical system 11 to generate an analog image signal. The output of the image sensor 13 is connected to the AFE 14.

  Here, in the photographing mode of the electronic camera, the image sensor 13 captures a still image for recording (main image) in response to the full pressing operation of the release button 21. The imaging element 13 in the shooting mode continuously takes images for observation (through images) at predetermined intervals even during standby for shooting. Here, the through-image data acquired in time series is used for moving image display on the monitor 20 and various arithmetic processes by the CPU 16.

  The AFE 14 is an analog front end circuit that performs analog signal processing on the output of the image sensor 13. The AFE 14 performs correlated double sampling, image signal gain adjustment, and A / D conversion of the image signal. The image signal output from the AFE 14 is input to the CPU 16.

  The attitude sensor 15 is a sensor that detects a change in the tilt of the shooting screen with the optical axis of the imaging optical system 11 as the rotation center. For example, the posture sensor 15 in one embodiment is configured by a known three-axis acceleration sensor that supports measurement of gravitational acceleration (static acceleration).

  Here, an example of setting the orientations of the three axes in the posture sensor 15 of one embodiment will be described with reference to FIG. In FIG. 2, on the assumption that the electronic camera is held at the normal position, the housing 23 of the electronic camera and the three axes (XYZ orthogonal coordinate system) of the attitude sensor 15 have the following positional relationship. In the above state, the Z-axis direction of the attitude sensor 15 coincides with the gravity direction, and the X-axis direction and the Y-axis direction of the attitude sensor 15 are orthogonal to the gravity direction. In the above state, the Y-axis direction of the attitude sensor 15 is set to be parallel to the optical axis of the imaging optical system 11.

  Further, the output of each axis of the attitude sensor 15 shows a “0” value when no gravity acceleration component is detected in the axial direction. For example, when the electronic camera is held in the normal position, the X-axis and Y-axis outputs of the attitude sensor 15 are “0” values, while the Z-axis output is a value other than “0”. On the other hand, when the attitude of the electronic camera is changed so that the “OP” direction shown in FIG. 2 coincides with the direction of gravity, the output of each axis of the attitude sensor 15 changes to a value other than “0”. . When the electronic camera is freely dropped, the output of each axis of the attitude sensor 15 shows a “0” value.

  FIG. 3A is a diagram illustrating an output example of the posture sensor 15 in a state where the electronic camera is tilted from the normal position with the Y axis as the rotation center (in the case of rolling). FIG. 3B is a diagram illustrating an output example of the posture sensor 15 in a state where the electronic camera is tilted from the normal position with the X axis as the rotation center (in the case of pitching). For simplicity, the illustration of the housing 23 of the electronic camera is omitted in FIG.

  As shown in FIG. 3A, when the electronic camera is tilted from the normal position with the Y axis as the center of rotation, the gravitational acceleration component varies in the X axis direction and the Z axis direction of the attitude sensor 15 according to the amount of rotation. Appears separated. Therefore, when the optical axis of the imaging optical system 11 is orthogonal to the direction of gravity, the CPU 16 uses the optical axis of the imaging optical system 11 as the rotation center based on the X-axis and Z-axis outputs of the attitude sensor 15. The inclination of the shooting screen can be obtained.

  On the other hand, as shown in FIG. 3B, when the electronic camera is tilted from the normal position with the X axis as the center of rotation, the gravitational acceleration component depends on the rotation amount in the Y axis direction and Z axis direction of the attitude sensor 15. Appears separately. Therefore, the CPU 16 can determine the inclination of the optical axis of the imaging optical system 11 with respect to the direction of gravity based on the Y-axis and Z-axis outputs of the attitude sensor 15.

  By the way, at the time of actual photographing, the photographing posture of the electronic camera changes with a complicated behavior in a three-dimensional space. Therefore, when obtaining the tilt of the shooting screen, it is more preferable to consider the tilt of the optical axis of the imaging optical system 11 with respect to the direction of gravity.

  For example, consider a case where the electronic camera is pitched upward (or downward) from the normal position and the electronic camera is rotated around the optical axis of the imaging optical system 11. In the above case, the gravitational acceleration component appears separately on the XYZ axes of the attitude sensor 15. At this time, if the inclination of the photographing screen is obtained by paying attention only to the X-axis and Z-axis outputs of the attitude sensor 15, the influence of gravity acceleration separated into the Y-axis direction and the Z-axis direction by pitching is not taken into consideration. The detection accuracy of the screen tilt decreases. Therefore, the CPU 16 in one embodiment obtains the tilt of the shooting screen using all the outputs of the XYZ axes of the attitude sensor 15.

  As an example, in a scene where a pet approaching the electronic camera is photographed from a high viewpoint, when the user moves the electronic camera in accordance with the movement of the subject, the inclination of the optical axis of the imaging optical system 11 gradually changes with respect to the direction of gravity. I will do it. However, even in the above situation, the CPU 16 can accurately detect a change in the tilt of the shooting screen based on the output of the XYZ axes of the attitude sensor 15.

  The CPU 16 is a processor that performs overall control of the operation of the electronic camera and performs various types of image processing. The CPU 16 functions as an image processing unit 24, an imaging condition adjustment unit 25, a template management unit 26, and a subject tracking unit 27 by executing a program stored in the second memory 18.

  The image processing unit 24 performs various types of image processing (color interpolation processing, gradation conversion processing, contour enhancement processing, white balance adjustment, etc.) on the digital image signal. The image processing unit 24 performs image resolution conversion (pixel number conversion). As an example, at the time of shooting standby in the shooting mode, the image processing unit 24 performs resolution conversion on the through image and generates a view image for monitor display.

  The imaging condition adjustment unit 25 executes known auto-focus (AF) control by contrast detection and known auto-exposure (AE) calculation using the through image data.

  The template management unit 26 generates template data for identifying the tracking target object from the input image. In the electronic camera of one embodiment, it is possible to generate a template with any object including a human being, an animal, a building, a vehicle, etc. as a tracking target. As an example, the template management unit 26 generates template data using a through image of the template generation range set in the shooting screen. The template data includes, for example, YCbCr channel data (subject luminance information and color difference information).

  Further, the template management unit 26 adjusts the orientation of the template based on the change in the tilt of the shooting screen based on the output of the attitude sensor 15.

  The subject tracking unit 27 continuously detects the position of the subject to be tracked in the shooting screen using the template. Thereby, the imaging condition adjustment unit 25 can perform AF control following the movement of the subject corresponding to the template. In addition, the CPU 16 can display a mark indicating the position of the subject corresponding to the template on the view image.

  The first memory 17 is a buffer memory that temporarily stores image data in the pre-process and post-process of image processing by the CPU 16. The first memory 17 is constituted by an SDRAM which is a volatile storage medium.

  The second memory 18 is configured by a non-volatile storage medium such as a flash memory. The second memory 18 stores the above-described template data and various types of data necessary for subject tracking processing (for example, data on the detection position of the tracking target and data on the tilt of the shooting screen). The second memory 18 also stores a program executed by the CPU 16. An operation example of subject tracking processing by this program will be described later.

  The recording I / F 19 is formed with a connector for connecting the nonvolatile storage medium 28. The recording I / F 19 executes data writing / reading with respect to the storage medium 28 connected to the connector. The storage medium 28 is composed of a hard disk, a memory card incorporating a semiconductor memory, or the like. In FIG. 1, a memory card is illustrated as an example of the storage medium 28.

  The monitor 20 displays various images according to instructions from the CPU 16. For example, at the time of shooting standby in the shooting mode, the view image is displayed as a moving image on the monitor 20 under the control of the CPU 16. At this time, the CPU 16 can also display various information necessary for photographing on the view image in an overlay manner. The CPU 16 can also display a menu screen for changing various settings on the monitor 20.

  The release button 21 receives from the user an instruction input for starting an AF operation before photographing by a half-press operation and an instruction input for starting an imaging operation by a full-press operation.

  The operation member 22 includes, for example, a command dial, a cross-shaped cursor key, a determination button, and the like. The operation member 22 receives various inputs of the electronic camera from the user. For example, the operation member 22 is used for an input operation on the menu screen, an operation mode switching operation of the electronic camera, a subject tracking instruction operation described later, and the like.

  Hereinafter, an operation example of subject tracking processing in one embodiment will be described with reference to the flowchart of FIG. The operation of the electronic camera during the subject tracking process is controlled by a program executed by the CPU 16.

  Here, the starting procedure of the subject tracking process shown in FIG. 4 will be described. First, when receiving an operation for selecting a photographing mode in which subject tracking is possible, the CPU 16 drives the image sensor 13 to start capturing a through image. Thereafter, the through images are sequentially generated at predetermined intervals.

  Then, the CPU 16 displays the view image generated from the through image on the monitor 20 as a moving image. At this time, the CPU 16 superimposes a guide mark (rectangular frame display) indicating the template generation range in the shooting screen on the view image (see FIG. 5). The frame display is displayed in white at the center of the shooting screen under the control of the CPU 16. When the user performs a subject tracking instruction operation (for example, pressing of the determination button on the operation member 22) while the subject to be tracked is contained in the frame display, the CPU 16 starts subject tracking processing described below. To do.

  Step S101: The imaging condition adjustment unit 25 executes AF control with the central portion of the shooting screen (the position of the frame display) as a focus detection area.

  When the focus position of the focus lens cannot be detected by the AF control in S101, the CPU 16 displays that the subject in the template generation range (the range corresponding to the frame display) is out of focus, and performs subject tracking. Cancel processing. This is because in the out-of-focus state, the electronic camera cannot generate an appropriate template from the through image in the template generation range.

  Step S102: The template management unit 26 generates a tracking target template using a through image captured after AF.

  As an example, the template management unit 26 cuts out a partial image in the template generation range from the above through images. Then, the template management unit 26 generates a template of luminance information (Y) to be tracked with reference to the luminance component of the partial image, and also refers to the color difference information (Cb, Cr) of the tracking target with reference to the color difference component of the partial image. ) Templates are generated. Note that the data of each template is recorded in the second memory 18 by the CPU 16.

Step S103: The CPU 16 obtains the inclination θ _{1 of the} imaging screen with the optical axis of the imaging optical system 11 as the rotation center based on the output of the orientation sensor 15 at the time of imaging the through image used for generating the template. Thereafter, the CPU 16 records data of the inclination θ ₁ of the shooting screen in the second memory 18.

Here, the CPU 16 in S103 uses the X-axis output value (X), the Y-axis output value (Y), and the Z-axis output value (Z) of the attitude sensor 15 by the following equation (1). The inclination θ _{1 of the} shooting screen is calculated.

なお、Ｓ１０２およびＳ１０３の処理が終了すると、被写体追尾部２７は上記のテンプレートを用いて被写体追尾処理を開始する。このとき、ＣＰＵ１６は、被写体追尾の実行状態を示す表示（被写体追尾マーク）をモニタ２０に出力する。一例として、ＣＰＵ１６は、図５に示すガイドマークの表示色を白色から黄色に変更する。これにより、ユーザーはテンプレートの生成完了と、被写体追尾が開始されたこととをモニタ２０で確認できる。

When the processes of S102 and S103 are completed, the subject tracking unit 27 starts the subject tracking process using the template. At this time, the CPU 16 outputs a display (subject tracking mark) indicating the subject tracking execution state to the monitor 20. As an example, the CPU 16 changes the display color of the guide mark shown in FIG. 5 from white to yellow. As a result, the user can confirm on the monitor 20 that the template generation has been completed and subject tracking has started.

  Step S104: The CPU 16 determines whether or not a determination frame for determining subject tracking is captured in the through image. When the determination frame is captured (YES side), the process proceeds to S105. On the other hand, when the determination frame is not captured (NO side), the CPU 16 waits for the determination frame to be captured.

Step S105: The CPU 16 obtains the inclination θ _{2 of the} photographing screen around the optical axis of the imaging optical system 11 based on the output of the attitude sensor 15 at the time of imaging of the determination frame (S104). Note that the calculation of θ ₂ in S105 is the same as that in S103, and therefore redundant description is omitted.

Step S106: The CPU 16 obtains the change amount Δθ of the inclination of the shooting screen from the time of template acquisition to the time of shooting of the determination frame. Specifically, the CPU 16 calculates the amount of change Δθ in the inclination of the shooting screen by taking the difference between θ ₁ obtained in S103 and θ ₂ obtained in S105 (Δθ = θ ₁ −θ ₂ ).

  Step S107: The template management unit 26 adjusts the orientation of the template so that the amount of rotation of the template with respect to the shooting screen increases according to the magnitude of the change in the tilt of the shooting screen. Note that the template management unit 26 in S107 similarly adjusts the orientations of the Y, Cb, and Cr templates.

  For example, the template management unit 26 rotates the template read from the second memory 18 according to the change amount Δθ (S106) by a known geometric conversion process. At this time, the template management unit 26 also executes a template re-sampling process and an interpolation process as necessary. As a result, a template whose rotation is corrected in accordance with the change amount Δθ of the inclination of the shooting screen is generated (see FIG. 6).

  Step S108: The subject tracking unit 27 executes a matching process for obtaining a similarity between the subject included in the determination frame (S105) and the template after rotation correction (S107). The matching process is performed on a subject included in a partial region (search area) of the determination frame. Further, the position of the search area is set, for example, centering on the position where the tracking target can be detected on the shooting screen at the previous determination (the center of the shooting screen at the first determination) ( (See FIG. 5).

  In the matching process of S108, the subject tracking unit 27 executes the following processes (A) to (C). Note that the following processing is performed for each template.

  (A) The subject tracking unit 27 determines a target area to be matched with the template from the determination frame. The size of this target area is set to the same size as the template after rotation correction.

  (B) Next, the subject tracking unit 27 obtains a gradation difference between target pixels at corresponding positions in the image of the target area set in (a) and the template after rotation correction. Then, the subject tracking unit 27 calculates the similarity in the above target area by the following equation (2). The similarity value is recorded in the second memory 18 by the subject tracking unit 27.

ここで、式（２）において、Ｉ₁はテンプレートに対応し、Ｉ₂は対象領域の画像に対応する。そして、Ｉ₁およびＩ₂の注目画素は、テンプレートおよび対象領域の画像でそれぞれ対応位置にある画素を示す。また、式（２）では、テンプレートおよび判定フレームでの階調がともに８ｂｉｔ（０〜２５５の階調値）であることを前提とする。なお、上記の類似度の単位は％である。すなわち、上記の式（２）では、対応画素の階調差の絶対値を合計して類似度を求めている。そして、式（２）では、階調差の絶対値の総和が大きくなるほど類似度の値が小さくなる。

Here, in Expression (2), I ₁ corresponds to a template, and I ₂ corresponds to an image of the target area. The target pixels of I ₁ and I ₂ indicate pixels at corresponding positions in the template and the image of the target area, respectively. Further, in the expression (2), it is assumed that the gradation in the template and the determination frame is 8 bits (gradation value of 0 to 255). Note that the unit of similarity is%. That is, in the above equation (2), the absolute value of the gradation difference of the corresponding pixels is summed to obtain the similarity. In equation (2), the similarity value decreases as the sum of the absolute values of the gradation differences increases.

  (C) The subject tracking unit 27 shifts the target area and repeats the process (B). Thereby, the subject tracking unit 27 obtains the similarity to the template at each position of the determination frame.

  Step S109: The subject tracking unit 27 determines whether or not the tracking target has been lost. Specifically, the subject tracking unit 27 determines whether all the similarities obtained in the matching process (S108) are less than a determination threshold value indicating a lost state. If the above requirement is satisfied (YES side), the process proceeds to S118. In this case (YES side of S109), the CPU 16 may output an error display indicating the tracking target lost to the monitor 20. On the other hand, when the above requirement is not satisfied (NO side), the process proceeds to S110.

  Step S110: The CPU 16 determines whether or not a subject tracking process stop operation has been accepted. When the subject tracking process is stopped (YES side), the process proceeds to S118. On the other hand, when there is no operation for stopping the subject tracking process (NO side), the process proceeds to S111.

  Step S111: The subject tracking unit 27 extracts the maximum value (maximum similarity) of the similarity obtained in S108. Then, the subject tracking unit 27 determines the position of the target area indicating the maximum similarity in the determination frame as the tracking target position.

  Then, the subject tracking unit 27 updates the display position of the subject tracking mark superimposed on the view image in accordance with the position of the tracking target. As a result, the position of the frame display on the monitor 20 shifts following the movement of the subject to be tracked. As a result, the user can check the detection result of the tracking target on the monitor 20.

  In addition, the subject tracking unit 27 records the detection position of the tracking target (determined in S111) in the second memory 18. The subject tracking unit 27 sequentially updates the data of the detection position of the tracking target stored in the second memory 18 every time the tracking target is detected.

  Step S112: The focus adjustment unit 41 sets the position of the subject to be tracked (S111) as a focus detection area and executes AF control.

  Step S113: The CPU 16 determines whether or not the release button 21 is half-pressed. When the release button 21 is half-pressed (YES side), the process proceeds to S114. On the other hand, when the release button 21 is not half-pressed (NO side), the CPU 16 returns to S104 and repeats the above operation.

  Step S114: The CPU 16 temporarily stops the tracking of the subject by the subject tracking unit 27. Then, the imaging condition adjustment unit 25 performs AF control using the position of the tracking target last detected in the subject tracking process (the detection position of the tracking target stored in the second memory 18) as a focus detection area. Thereafter, the imaging condition adjustment unit 25 stops the AF control and fixes the focus position of the focus lens until the actual image is captured or the half-press operation of the release button 21 is released.

  Note that the imaging condition adjustment unit 25 in S114 may execute AE calculation by spot photometry with the position of the tracking target as a reference.

  Step S115: The CPU 16 determines whether or not the half-press of the release button 21 has been released. When the half-press of the release button 21 is released (YES side), the CPU 16 returns to S104 and resumes tracking of the subject. On the other hand, when the half-press of the release button 21 is continued (NO side), the process proceeds to S116.

  Step S116: The CPU 16 determines whether or not the release button 21 is fully pressed. When the release button 21 is fully pressed (YES side), the process proceeds to S117. On the other hand, when the release button 21 is not fully pressed (NO side), the CPU 16 returns to S115 and repeats the above operation.

  Step S117: The CPU 16 drives the image pickup device 13 to execute an image pickup process for the main image. The data of the main image is recorded in the storage medium 28 via the recording I / F 19 after predetermined processing is performed by the AFE 14 and the image processing unit 24.

  Step S118: The CPU 16 executes a tracking end process. For example, the CPU 16 initializes various types of subject tracking processing data (template data, tracking target detection position data, and shooting screen tilt data) stored in the second memory 18. Then, the CPU 16 turns off the subject tracking mark of the view image and ends the series of processes. Above, description of the flowchart of FIG. 4 is complete | finished.

  Hereinafter, the operational effects of the embodiment will be described. The electronic camera of one embodiment detects the subject to be tracked by rotating the template in accordance with the change in the tilt of the shooting screen and applying the template after the rotation correction (S107, S108). Therefore, as shown in FIG. 6, even when the tilt of the shooting screen is different between the template generation time (T1 in FIG. 6) and the time when the determination frame is shot (T2 in FIG. 6), Since the orientation of the template is adjusted, the tracking target can be detected with high accuracy.

<Description of other embodiments>
FIG. 7 is a flowchart of an operation example of subject tracking processing in another embodiment. Here, the processing from S201 to S212 in FIG. 7 corresponds to the processing from S101 to S112 in FIG. 4, respectively. Also, the processing from S215 to S220 in FIG. 7 corresponds to the processing from S113 to S118 in FIG. 4, respectively. For this reason, in other embodiments, a duplicate description regarding the above processing is omitted. In addition, since the structure of the electronic camera in other embodiment is common in FIG. 1, duplication description is abbreviate | omitted.

  Step S213: The template management unit 26 updates the tracking target template using the image of the tracking target detection position cut out from the determination frame (S204). At this time, the template management unit 26 generates all templates (Y, Cb, Cr). The updated data of each template is recorded in the second memory 18 by the CPU 16.

Step S214: The CPU 16 rewrites the value of θ ₁ stored in the second memory 18 to the value of θ ₂ at the time of imaging of the determination frame (obtained in S205). As a result, in the next determination frame, the CPU 16 calculates the amount of change in the tilt of the shooting screen since the template was updated. Above, description of FIG. 7 is complete | finished.

  In the electronic camera according to another embodiment, the template is sequentially updated when the tracking target is successfully detected using the rotation-corrected template (S213). Therefore, even when the shape or brightness of the tracking target changes gently during the subject tracking process, the electronic camera can accurately perform the subject tracking process.

<Supplementary items of the embodiment>
(1) The configuration of the posture sensor 15 of the present invention is not limited to the example of the above embodiment. For example, a biaxial acceleration sensor that detects the output of two axes (X axis and Z axis in FIG. 2) orthogonal to the optical axis of the imaging optical system 11 is applied so that the CPU 16 obtains the tilt of the shooting screen. May be.

  (2) In the one embodiment described above, the electronic camera may return to S104 and continue the subject tracking process after capturing the main image (S117). In the above-described embodiment, the electronic camera may end the subject tracking process when the half-press of the release button 21 is released (YES side of S115).

  (3) In the above-described embodiment, the example in which the luminance information and color difference information templates to be tracked are generated has been described. However, the above embodiment is merely an example, and the imaging apparatus according to the present invention may selectively generate one of the above-described templates of luminance information and color difference information. In addition, the subject tracking unit 27 may detect the tracking target from the through image using, for example, information on the RGB gradation values of the image, the contour component of the image, or the contrast ratio of the image.

  (4) In the above embodiment, an example has been described in which the functions of the image processing unit 24, the imaging condition adjustment unit 25, the template management unit 26, and the subject tracking unit 27 are realized by software. Alternatively, the entire configuration may be realized by hardware.

  (5) In the above-described embodiment, the template data, the similarity value data, the tracking target detection position data, and the shooting screen tilt data may be stored in the first memory 17, respectively. .

  (6) In the above embodiment, the configuration example of the compact electronic camera has been described. However, the imaging apparatus of the present invention can also be applied to a single-lens reflex type electronic camera with interchangeable lenses. When the present invention is applied to a single-lens reflex type electronic camera, a through image may be picked up by the image pickup device 13 for picking up the main image, and separately from the image pickup device 13 for picking up the main image. You may provide the image pick-up element for imaging a through image. The imaging device of the present invention can also be applied to a camera module built in an electronic device such as a mobile phone.

  (7) The configurations of the above embodiment and the modification are merely examples. Therefore, when implementing the imaging apparatus of the present invention, all combinations of the configurations shown in the above-described embodiments and supplementary items and the order of the processing can be taken.

  It should be noted that the present invention can be implemented in various other forms without departing from the spirit or main features thereof. Therefore, the above-described embodiment is merely an example in all respects and should not be interpreted in a limited manner. The present invention is defined by the claims, and the present invention is not limited to the text of the specification. Further, all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

1 is a block diagram illustrating a schematic configuration of an electronic camera according to an embodiment. The figure which shows the example of a setting of direction of 3 axes | shafts in an attitude | position sensor (A) Schematic diagram showing an output example of a posture sensor in a state where the electronic camera is tilted from the normal position with the Y axis as the rotation center, (b) posture sensor in a state where the electronic camera is tilted from the normal position with the X axis as the rotation center Schematic diagram showing an output example Flow chart of an example of subject tracking processing in one embodiment The figure which shows the example of a display of the view image on which the guide mark was superimposed Schematic diagram showing the relationship between the change in the tilt of the shooting screen and the rotation of the template Flow chart of an operation example of subject tracking processing in another embodiment

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Imaging optical system, 13 ... Image sensor, 15 ... Attitude sensor, 16 ... CPU, 18 ... 2nd memory, 24 ... Image processing part, 26 ... Template management part, 27 ... Subject tracking part

Claims (3)

An imaging unit that captures a subject image in a shooting screen via an imaging optical system;
A memory for storing a template indicating the characteristics of the tracking target;
An attitude sensor that detects an inclination of the shooting screen with the optical axis of the imaging optical system as a rotation center;
A control unit that adjusts the orientation of the template so that the amount of rotation of the template with respect to the shooting screen increases according to the magnitude of the change in the inclination of the shooting screen;
A subject tracking unit that continuously detects the subject to be tracked from the shooting screen using the template after adjustment;
An imaging apparatus comprising: The imaging device according to claim 1,
The imaging apparatus according to claim 1, wherein the posture sensor is an acceleration sensor capable of detecting an inclination of an optical axis of the imaging optical system with respect to a direction of gravity. In the imaging device according to claim 1 or 2,
The control device updates the template based on an output of the imaging unit at the time of detection when the subject to be tracked can be detected using the adjusted template.

Images