JP2019092037A - Imaging apparatus and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform blur correction of a subject by suppressing the influence of an error of a moving amount on an image plane of a subject detected from a temporally continuous image. SOLUTION: It is calculated by a first calculation means for calculating an angular velocity of a subject with respect to an image pickup device and a first calculation means based on a motion vector of the subject and a movement of the image pickup device based on a temporally continuous image. The second calculation means for calculating the angular velocity of the subject with respect to the image pickup device based on the plurality of angular velocities, and the angular velocity of the subject with respect to the image pickup device at the time of exposure according to the angular acceleration calculated by the second calculation means. The determination means includes a determination means for determining and a correction means for correcting the image blur of the subject by moving the correction element based on the angular velocity determined by the determination means, and the determination means is the angular velocity calculated by the first calculation means. The angular acceleration used to determine the angular velocity of the subject with respect to the image pickup apparatus at the time of exposure is changed depending on whether or not the angular acceleration calculated by the second calculation means is included in the value range corresponding to the above. [Selection diagram] Fig. 1

Description

  The present invention relates to blur correction of an image that occurs during so-called panning photography.

  Conventionally, panning photography is known as a photography technique for expressing the feeling of speed of a moving subject. The purpose of the follow shot shooting is to cause the moving subject to stand still and the background to flow by the cameraman panning the camera according to the movement of the subject. In the follow-up shooting, it is necessary for the photographer to pan the camera according to the movement of the subject, but when the panning speed is too fast or too slow, a difference occurs between the moving speed of the subject and the panning speed. In many cases, the subject is blurred.

  Therefore, in Patent Document 1, based on the relative angular velocity of the subject relative to the imaging device calculated before exposure and the angular velocity of the imaging device during exposure obtained from the angular velocity sensor, a part of the optical system or imaging unit of the lens being exposed It is moved to correct blurring of the subject (subject blur). Further, in Patent Document 1, the relative angular velocity of the subject with respect to the imaging device is calculated based on the amount of movement on the image plane of the subject detected from the temporally continuous image and the output of the angular velocity sensor.

JP-A-4-163535

  However, the technique disclosed in Patent Document 1 detects the movement of the subject and performs blur correction, but does not take into consideration the error of the movement amount on the image plane of the subject detected from the temporally continuous image. As a method of detecting the amount of movement of the subject on the image plane from temporally continuous images, the object area and the background area are separated using the output of the angular velocity sensor, and the motion vector between consecutive images of the subject area is detected There is a method of detecting the amount of movement of the subject on the image plane by doing this. In this method, when the camera is panned slowly, it is difficult to separate the subject area and the background area, and it becomes difficult to accurately obtain the amount of movement of the subject on the image plane from the continuous image. Therefore, there are cases where the calculated relative angular velocity of the subject with respect to the imaging device deviates from the actual relative angular velocity, and it is not possible to accurately perform the blur correction of the subject.

  Therefore, it is an object of the present invention to be able to perform blur correction of a subject while suppressing the influence of the error of the movement amount on the image plane of the subject detected from temporally continuous images.

  An imaging apparatus according to the present invention is an imaging apparatus capable of panning, and based on a motion vector of a subject and a motion of the imaging apparatus based on temporally continuous images, an angular velocity of the subject relative to the imaging apparatus. A second calculation unit for calculating the angular acceleration of the subject with respect to the imaging device based on the plurality of angular velocities calculated by the first calculation unit; A determination unit that determines an angular velocity of the subject relative to the imaging device at the time of exposure according to the angular acceleration calculated by the calculation unit; and a correction element is moved based on the angular velocity determined by the determination unit; Correction means for correcting blurring, wherein said determination means is calculated by said second calculation means in a range corresponding to the angular velocity calculated by said first calculation means Depending on whether include acceleration, and changes the angular acceleration is used to determine the angular velocity of the object relative to the imaging device at the time of exposure.

  According to the present invention, it is possible to perform the shake correction of the subject while suppressing the influence of the error of the movement amount on the image plane of the subject detected from the temporally continuous image.

It is a figure which shows the to-be-exposed object angular velocity determination processing concerning the Example of this invention. It is a figure which shows the imaging | photography process at the time of the follow shot assist mode concerning the Example of this invention. It is a figure which shows the structure of the camera concerning the Example of this invention. It is a figure showing composition of a vibration control system concerning an example of the present invention. It is a figure which shows the panning control concerning the Example of this invention. FIG. 2 is a diagram showing a configuration of a drive control system of a shift lens in a follow shot assist mode according to an embodiment of the present invention. It is a figure which shows the angular velocity data at the time of panning. It is a figure which shows the relationship between the relative angular velocity of a to-be-photographed object, and angular acceleration. It is a figure explaining the relative angular velocity of a to-be-photographed object.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Example)
FIG. 3 is a block diagram showing the configuration of a lens-integrated camera as an imaging apparatus according to a first embodiment of the present invention. The camera 100 includes a photographing lens unit 101 which is a photographing optical system for forming light from a subject. The taking lens unit 101 includes a main lens 102, a zoom lens 103 whose focal length can be changed, and a focus lens (not shown) that performs focus adjustment. Furthermore, the photographing lens unit 101 includes a shift lens 104 that optically corrects blurring of a subject image by moving in a direction orthogonal to the optical axis. The shift lens 104 moves in a direction perpendicular to the optical axis for follow-up assistance for reducing blurring of the subject image during continuous shooting where the user shoots a moving subject while changing the direction by panning the camera 100. (Shiftable) is possible. The main lens, the zoom lens, the focus lens, and the shift lens included in the photographing lens unit 101 are each configured by at least one or more lenses. The camera 100 further includes a zoom encoder 105 that detects the position of the zoom lens 103, a position sensor 106 that detects the position of the shift lens 104, and an angular velocity sensor 107 such as a gyro sensor that detects the movement of the imaging device. The camera 100 further includes an amplifier 108 for amplifying the output of the angular velocity sensor 107, a camera control microcomputer (hereinafter, microcomputer) 130, a driver 109 for driving the shift lens 104, and an amplifier 110 for amplifying the output of the position sensor 106.

  The camera 100 further includes a shutter 111, an image sensor 112, an analog signal processing circuit 113, a camera signal processing circuit 114, a timing generator 115, an operation switch 116, a shutter driving motor 117, and a driver 118.

  The imaging element 112 is formed of a photoelectric conversion element such as a CMOS sensor or a CCD sensor, photoelectrically converts an object image formed by the photographing lens unit 101, and outputs an analog electric signal. The shutter 111 controls the exposure time of the image sensor 112.

  The analog signal processing circuit (AFE) 113 amplifies the analog signal output from the imaging element 112, converts the amplified analog signal into an imaging signal as a digital signal, and outputs the image signal to the camera signal processing circuit 114.

  The camera signal processing circuit 114 generates a video signal (captured video) by performing various image processing on the imaging signal. The photographed image (or the still image taken out from here) is recorded on a memory card 119 which can be attached to and detached from the camera 100, or displayed on a monitor (hereinafter referred to as an LCD) 120 constituted by display elements such as a liquid crystal panel. Be done. Further, the camera signal processing circuit 114 includes a motion vector detection unit 135 which detects a motion vector between frame images constituting a video signal.

  The timing generator 115 sets the operation timing of the image sensor 112 and the analog signal processing circuit 113. The operation switch 116 includes various switches such as a power switch, a release switch, a mode selection switch, and a dial. In the camera 100 of the present embodiment, switching between the follow shot assist mode and the normal shooting mode is possible through the operation of the mode selection switch. The shutter drive motor 117 is driven by the driver 118 to charge the shutter 111.

  The microcomputer 130 further includes an image stabilization control unit 131, a panning control unit 132, a shutter control unit 133, and an object angular velocity calculation unit 134.

  The image stabilization control unit 131 performs camera shake correction control (image stabilization control) that controls driving of the shift lens 104 in order to correct (reduce) the shake of the subject image caused by camera shake.

  The follow shot control unit 132 controls shift drive of the shift lens 104 for the follow shot assist.

  The shutter control unit 133 releases the power supply to the release electromagnetic magnet (not shown) through the driver 118 to open the shutter 111 in the charged state, and controls the shutter drive motor 117 to perform the charge operation of the shutter 111. .

  The subject angular velocity calculation unit 134 calculates the relative subject angular velocity of the subject to be photographed with respect to the camera 100. The microcomputer 130 also performs focus lens control, aperture control, and the like.

  For camera shake correction, for example, detection and correction are performed on two axes orthogonal to each other in the horizontal direction and the vertical direction. However, only one axis is described in this embodiment because it has the same configuration.

  When the power switch of the operation switch 116 is operated and the power of the camera 100 is turned on, the microcomputer 130 detects a change in state thereof, and power supply to each circuit of the camera 100 and initialization are performed.

  In the normal shooting mode in which the follow shot assist mode is not set, the angular velocity sensor 107 detects the shake of the camera 100 due to camera shake or the like, and uses the detection result to drive the shift lens 104 by the image stabilization control unit 131. A shake correction operation is performed.

  Here, the camera shake correction function will be described. FIG. 4 is a diagram showing the configuration of the vibration control system in the present embodiment. The same reference numerals as in FIG. 3 denote the same parts as in FIG. 3, and a description thereof will be omitted. In FIG. 4, reference numerals 401 to 407 indicate the detailed configuration of the image stabilization control unit 131. The A / D converter 401 converts an analog signal as an angular velocity signal output from the angular velocity sensor 107 (amplifier 108) into a digital signal as angular velocity data. The output data sampling of the angular velocity sensor 107 is performed at about 1 to 10 kHz.

  The filter calculation unit 402 is configured by a high pass filter (HPF) or the like, and reduces an offset component included in angular velocity data, or changes the cutoff frequency of the HPF. The first integrator 403 converts angular velocity data into angular displacement data to generate drive target data of the shift lens 104. The A / D converter 406 converts an analog signal as a position signal of the position sensor 106 into a digital signal as position data. The first adder 404 subtracts the current shift lens position from the drive target value of the shift lens 104 to calculate drive data of the shift lens 104. The PWM output unit 405 outputs the calculated drive amount data to the driver 109 for driving the shift lens.

  The panning control unit 407 determines from the angular velocity data whether the camera 100 has been panned. In addition, when it is determined that the panning is performed, the panning control unit 407 performs cut-off frequency change control of the filter operation unit 402 and adjustment of the output of the first integrator 403.

  FIG. 5 is a diagram showing an example of a flowchart of panning control performed by the panning control unit 407. As shown in FIG.

  In step S501, the panning control unit 407 determines whether the average value of angular velocity data fetched from the A / D converter 401 (average value for a predetermined number of samplings, hereinafter referred to as angular velocity average value) is larger than a predetermined value α. Determine When the angular velocity average value is equal to or less than the predetermined value α, the panning control unit 407 determines that panning is not performed, and proceeds to step S507. On the other hand, if it is larger than the predetermined value α, the panning control unit 407 proceeds to step S502 and determines whether the angular velocity average value is larger than the predetermined value β. Then, if the angular velocity average value is equal to or less than the predetermined value β, the panning control unit 407 determines that slow (low speed) panning is being performed, and proceeds to step S506. If the value is larger than the predetermined value β, it is determined that rapid (fast) panning is being performed, and the process proceeds to step S503.

  The panning control unit 407 sets the cutoff frequency of the HPF of the filter calculation unit 402 to the maximum value in step S503, and forcibly turns off the camera shake correction control (non-execution state) in step S504. When anti-vibration control is turned off during high-speed panning, if high-speed panning is treated as a large hand shake and shift lens 104 is shifted, the shot image moves significantly when shift lens 104 reaches the shift end and the photographer is notified It is to give a sense of discomfort. In addition, when high-speed panning is performed, the movement of the captured image due to panning is large, and even if an image blur due to camera shake appears, the photographer hardly feels a sense of discomfort. Then, by setting the cutoff frequency of the HPF to the maximum value and then stopping the shift lens 104 gradually in the next step, an image blur due to camera shake appears suddenly when the image stabilization control is turned off, which makes the photographer uncomfortable. Can be avoided.

  Thereafter, in step S505, the panning control unit 407 gradually changes the output of the first integrator 403 from the current data to data of the initial position. Thereby, the shift lens 104 gradually returns to the initial position, because it is desirable that the position of the shift lens 104 be at the initial position of the drive range when the camera shake correction operation is restarted next.

  In step S506, the panning control unit 407 sets the cutoff frequency of the HPF according to the magnitude of the angular velocity data. This is because it is necessary to correct the image blurring due to camera shake at the time of low speed panning, which is likely to be noticeable. The cutoff frequency is set so as to be able to correct image blurring due to camera shake while keeping the followability of the captured image to panning unnaturally.

  In step S507, the panning control unit 407 sets the cutoff frequency of the HPF to a normal value.

  In step S508, the panning control unit 407 cancels the forced OFF setting of the image stabilization control (turns on the image stabilization control).

  FIG. 7 is a diagram showing the relationship between angular velocity data in the horizontal direction at the time of panning and predetermined values α and β, and 701 in the drawing is angular velocity data sampled. In this example, angular velocity data in the + direction when the camera 100 is panned to the right, and angular velocity data in the − direction when panned to the left are obtained. In the example of FIG. 7, rapid (fast) panning in the right direction and slow (slow) panning in the left and right direction are detected.

  As can be seen from FIG. 7, the angular velocity data largely deviates from the initial value (here, 0) during panning. Therefore, when the angular velocity data is integrated to calculate the target position data of the shift lens 104, the output of the first integrator 403 becomes a very large value due to the DC offset component, resulting in an uncontrollable state. . Therefore, when panning is detected, it is necessary to cut the DC component by changing the HPF cutoff frequency to a high value. The output of the first integrator 403 is prevented from increasing by raising the cut-off frequency further, since this is particularly noticeable in the case of rapid panning. In the case of rapid panning, the movement of the image due to panning becomes very large with respect to camera shake, so that no sense of discomfort occurs even when the camera shake correction function is turned off in the panning direction.

  By performing panning control as described above, it is possible to obtain an image without discomfort even during panning.

  In FIG. 3, when the panning assist mode is set by the operation switch 116, the motion vector detection unit 135 of the camera signal processing circuit 114 detects the motion vector of the subject from the captured image. The detected motion vector is input to the follow shot control unit 132. At the same time, the panning control unit 132 receives angular velocity data from the angular velocity sensor 107 (amplifier 108).

  When the photographer is performing follow-up shooting, the motion vector of the subject output from the motion vector detection unit 135 is a vector corresponding to the main subject that the photographer is about to shoot and a vector corresponding to the flowing background. There are two types. At this time, since the purpose is panning, the data with the smaller amount of motion among the two types of detected motion vectors is the motion vector of the main subject, and the value of this motion vector is the amount of movement of the main subject on the image plane Represents

  On the other hand, since the angular velocity data corresponds to the panning velocity (following velocity) of the camera 100, the difference between the angular velocity data, the movement amount of the main subject on the image plane, and the angular velocity calculated from the current focal distance of the lens Is the angular velocity of the main subject relative to the camera 100. The object angular velocity calculation unit 134 calculates the angular velocity (also referred to as relative object angular velocity) of the main object with respect to the camera 100 at each time of processing the monitor image. Further, the subject angular velocity calculation unit 134 sends the pairing information of the calculated relative subject angular velocity and the calculated time (acquisition time) to the panning control unit 132.

  FIG. 6 is a diagram showing the configuration of a drive control system of the shift lens 104 in the follow shot assist mode, and the same reference numerals as in FIGS. 3 and 4 denote the same components. The camera information acquisition unit 601 is a follow shot setting information indicating that the follow shot assist mode has been set by the operation of the mode selection switch of the operation switch 116, and release information indicating that shooting is instructed by the operation of the release switch. To get The angular velocity data output unit 602 samples angular velocity data at a predetermined timing and outputs the sampled data to the object angular velocity calculation unit 134.

  The subject angular velocity determination unit 603 obtains the combination information of the relative subject angular velocity calculated by the subject angular velocity calculation unit 134 and its calculation time before photographing for recording (before exposure of the image sensor 112 for recording a still image). Hold (accumulate) as angular velocity history. In the following description, exposure means photographing for recording. Then, the subject angular velocity determination unit 603 uses the angular velocity history before the exposure (before the exposure period) to determine the relative object angular velocity which is the predicted angular velocity (prediction information) of the subject relative to the camera 100 during the exposure period (during shooting). Is determined by calculation etc. In this way, the subject angular velocity determination unit 603 determines the relative subject angular velocity in the obtained exposure period as the relative subject angular velocity used for control of the shift drive of the shift lens 104 in the exposure period in the follow shot assist.

  The second adder 604 calculates the difference between the angular velocity data from the angular velocity sensor 107 and the relative object angular velocity in the exposure period determined by the object angular velocity determination unit 603. The second integrator 605 performs the integration operation only during the exposure period. The setting change unit 606 changes the setting of the panning control unit 407 according to the notification of the setting information of the follow shot assist mode from the camera information acquisition unit 601.

  When the panning assist mode is set by the operation of the operation switch 116, the camera information acquisition unit 601 notifies the setting changing unit 606 of the panning setting information. The setting change unit 606 changes the setting of the panning control unit 407 according to the notified panning setting information. The setting change performed here is a change that facilitates transition to the rapid panning state, and more specifically, changes the above-described predetermined values β and α for the panning determination.

  The second adder 604 calculates the difference between the angular velocity data from the angular velocity sensor 107 and the relative object angular velocity from the object angular velocity determination unit 603, and sends the calculation result to the second integrator 605.

  In response to the release information from the camera information acquisition unit 601, the second integrator 605 starts the integration operation of the aforementioned difference during the exposure period. The second integrator 605 outputs a value such that the position of the shift lens 104 is at the initial position (center) during a period other than the exposure period. Here, when the shift lens 104 is to be disposed at the center position except during the exposure period, the shift lens 104 moves sharply from the current position to the center position at the end of the exposure period. However, immediately after the end of the exposure period, because the image signal is read out from the image sensor 112, the display of the photographed image is not performed on the LCD 120. It must not be.

  The output of the second integrator 605 is added to the output of the first integrator 403 in the first adder 404, and the position sensor 106 (shift position A / D converter 406) is added to the added value. The shift position data of the shift lens 104 from is subtracted. Thus, drive amount data of the shift lens 104 is calculated.

  The panning control unit 407 immediately starts panning control when the photographer performs a panning shot by high-speed panning while the panning shot assist mode is set, and the image stabilization is performed as described in step S504 in FIG. 5. Turn off the control. An image plane of an object image corresponding to a difference between an angular velocity by panning of the camera 100 and a relative angular velocity of an object relative to the camera 100 (hereinafter simply referred to as an object) by moving the shift lens 104 by panning control. Correct the displacement amount above. For this reason, the difference between the panning speed of the camera 100 and the movement speed of the subject during the exposure period which causes the failure in the follow shot is offset by the shift driving of the shift lens 104, and as a result, the follow shot succeeds.

  Here, the object angular velocity determination unit 603 determines the relative object angular velocity during the exposure period using the angular velocity history acquired and accumulated from the object angular velocity calculation unit 134 before exposure, but at that time the exposure time lag time and exposure Consider the period. For example, in the case where a subject performing uniform linear motion is followed by a camera 100 positioned in a direction orthogonal to the traveling direction, the angular velocity of the subject measured from the camera 100 changes continuously. For this reason, the angular velocity of the subject is not the same during detection and during the exposure period. Therefore, if the change in the angular velocity (that is, the acceleration) is not taken into consideration, the correction by the shift drive of the shift lens 104 can not be satisfactorily performed.

  FIG. 8 is a diagram showing the relationship between the relative angular velocity of the subject and the angular acceleration, and as shown in FIG. 9, the angular velocity of the subject (train) performing constant linear motion is in the direction orthogonal to the traveling direction of the subject. The change in the angular velocity as measured from the camera 100 located is shown. In FIG. 9, the subject is in uniform linear motion at a velocity v from left to right. Point A is a position at which the distance from the camera 100 is shortest (hereinafter referred to as the origin) on the movement locus of the object at constant linear motion, and L is the distance from the camera 100 to the origin A (shortest distance to the movement locus ). θ is an angle formed by the direction from the camera 100 to the subject with respect to the direction from the camera 100 toward the origin A, that is, the direction orthogonal to the traveling direction of the subject (that is, the orientation of the camera 100: hereinafter referred to as a panning angle) The right side of the origin A is positive and the left side is negative.

  The horizontal axis in FIG. 8 indicates the panning angle θ that is 0 degrees when the subject in FIG. 9 is located at the origin A, and the vertical axis in the middle indicates the angular velocity of the subject. The solid line graph shows the change in angular velocity. Also, the vertical axis on the right side indicates angular acceleration, and the broken line graph indicates changes in angular acceleration. The change in angular acceleration referred to here is a change in angular acceleration of the subject corresponding to the position of the subject based on the position of the camera. FIG. 8 shows the angular velocity and the angular acceleration when the shortest distance from the camera 100 to the origin point A is 20 m and the subject is in uniform linear motion at a velocity of 60 km / h.

  In FIG. 8, when the object passes through the origin A (θ = 0 degrees), the angular velocity is at a maximum and the angular acceleration is zero. The angular acceleration is maximized at θ = + 30 degrees, and is minimized at θ = −30 degrees. The relationship between the panning angle θ and the angular acceleration and the angular acceleration does not depend on the shortest distance or the speed of the object described above.

  FIG. 2 is a view showing a flowchart of photographing processing in the follow shot assist mode. The microcomputer 130 executes this process in accordance with a follow shot assist control program which is a computer program.

  In step S201, the microcomputer 130 determines whether or not the release switch has been half-pressed (SW1 ON). If the half-pressing operation is performed (SW1 is ON), the process proceeds to step S202, and the time measurement counter is incremented. If the half-pressing operation is not performed (SW1 is not ON), the process proceeds to step S203, the time measurement counter is reset, and the process returns to step S201.

  In step S204, the microcomputer 130 confirms whether or not the relative object angular velocity (simply referred to as the object angular velocity in the drawing) has already been calculated by the object angular velocity calculation unit 134. If it has been calculated, the microcomputer 130 proceeds to step S205 and confirms whether the time measurement counter has reached a predetermined time T or not. If the relative object angular velocity has not been calculated yet, and if the relative object angular velocity has already been calculated, and if the time measurement counter has reached the predetermined time T (the exposure period is longer than the predetermined time T), the microcomputer 130 proceeds to step S206. Go to

  In step S206, the microcomputer 130 causes the subject angular velocity calculation unit 134 to calculate the relative subject angular velocity. Thereby, the subject angular velocity calculation unit 134 calculates the relative object angular velocity before exposure which is started in response to the full-press operation of the release switch described later, and the object angular velocity determination unit 603 acquires the angular velocity history. The reason why the relative object angular velocity is recalculated when the time measurement counter has reached the predetermined time T is to consider the possibility of the speed of the object changing within the predetermined time T. The relative object angular velocity calculated by the object angular velocity calculation unit 134 is sent to the object angular velocity determination unit 603 each time it is calculated. If the time measurement counter has not yet reached the predetermined time T in step S205, the microcomputer 130 proceeds to step S208.

  In step S207 after step S206, the microcomputer 130 causes the subject angular velocity determination unit 603 to determine the relative subject angular velocity during the exposure period. Details of the processing here will be described later. Then, the process proceeds to step S208.

  In step S208, the microcomputer 130 determines whether or not the release switch has been full-pressed (SW2 ON). If the full-press operation is not performed (SW2 is not ON), the microcomputer 130 returns to step S201. On the other hand, when the full-press operation is performed (SW2 is ON), the microcomputer 130 proceeds to step S209, opens the shutter 111 through the shutter control unit 133, and starts the exposure.

  Further, in step S210, the microcomputer 130 causes the follow shot control unit 132 to perform drive control of the shift lens 104 in accordance with the relative object angular velocity determined in step S207. In this way, a follow shot assist is performed to correct the amount of displacement of the object image on the image plane. At this time, when it is determined in step S502 in FIG. 5 that the panning is high-speed panning, the microcomputer 130 drives the shift lens 104 through the image stabilization control unit 131 to correct image blurring due to camera shake.

  Subsequently, in step S211, the microcomputer 130 determines whether or not the exposure is completed. If completed, the process proceeds to step S212, and if not completed, the process returns to step S210. In step S212, the microcomputer 130 determines again whether or not the release switch is full-pressed (SW2 ON), and if full-pressed (SW2 ON), the process returns to step S209 to perform the next exposure (continuous shooting Shoot the next frame of On the other hand, when the full-press operation is not performed (SW2 ON is not performed), the process returns to step S201.

  FIG. 1 is a view showing a flowchart of an exposure-time object angular velocity determination process performed by the object angular velocity determination unit 603 in step S207 of FIG. This process is executed by the subject angular velocity determination unit 603 according to a follow shot assist control program which is a computer program, and this process is started when notification of the subject angular velocity is received in step S206.

  In step S101, the subject angular velocity determination unit 603 reads the angular velocity histories ω (n−p) to ω (n) (a plurality of angular velocities) before exposure which have been calculated and stored by the subject angular velocity calculation unit 134. Here, ω (n) represents the latest object angular velocity calculated in step S206 of FIG. 2, and nn3 and p ≧ 1.

  In step S102, the subject angular velocity determination unit 603 determines, from the read angular velocity histories ω (n−p) to ω (n), an angular acceleration α (n) which is a displacement amount per unit time using, for example, the least squares method. Calculate

  In step S103, the object angular velocity determining unit 603 calculates (predicts) an angular velocity ωexpect (n) expected at the time of calculation of ω (n) from the angular acceleration α (n−1) calculated immediately before.

  In step S104, the subject angular velocity determination unit 603 calculates a value range (a range of possible values) A (α (n)) of the angular acceleration α (n) from the calculated ωexpect (n).

Here, a method of calculating the value range A (α (n)) will be described with reference to FIG. v is the subject speed, L is the shortest distance between the moving path of the subject and the camera, and t is the moving time from the point of the subject to the shortest distance point between the moving path of the subject and the camera.
Since the angular velocity ω of the subject is a time derivative of θ,

, And from FIG.

It becomes. here,

If (Equation 1) is

It becomes. Furthermore, since the angular velocity α of the subject is a time derivative of ω,

Represented by, where

If it is (formula 5),

It becomes. If this α is expressed by the equation of ω,

  Further, when expressed by the expressions of ω and θ using (Expression 2),

It becomes.

  Here, as described above with reference to FIG. 8, the angular acceleration becomes maximum at θ = −30 degrees, and the angular acceleration becomes minimum at θ = + 30 degrees, and ωexpect (n) is at each angle. Assuming that it is an angular velocity, the angular acceleration α (n) is

Is necessarily included in the range A (α (n)) represented by Alternatively, if the domain of θ is defined, the range A (α (n)) is further refined.

  In step S105, the subject angular velocity determination unit 603 determines whether or not the angular acceleration α (n) is included in the range A (α (n)). If it is included, the object angular velocity determination unit 603 proceeds to step S106, otherwise proceeds to step S107.

  In step S107, the subject angular velocity determination unit 603 determines whether the difference between the angular acceleration α (n) and the range A (α (n)) is equal to or greater than a threshold. If it is the threshold value or more, the process proceeds to step S108, and if not, the process proceeds to step S109.

  In step S108, the subject angular velocity determination unit 603 sets the value of the angular acceleration α (n) to zero. This is equivalent to stopping the determination (prediction) of the object angular velocity in step S106 described later. After setting the angular acceleration α (n), the process proceeds to step S106.

  In step S109, the subject angular velocity determination unit 603 sets the value of the angular acceleration α (n) to the maximum value or the minimum value of the range A (α (n)), whichever is closer. After setting the angular acceleration α (n), the process proceeds to step S106.

  Although the object angular velocity determination unit 603 sets the value of the angular acceleration α (n) to 0 in step S108, it simply sets some exceptional value and determines the exceptional value in the follow shot control unit 132 in step S210 of FIG. And the follow shot assist may be stopped. Alternatively, a step is newly provided to determine whether the number of times the angular acceleration α (n) is not included in the range A (α (n)) is equal to or greater than the second threshold. Any exception value may be set to stop the shooting assist.

  In step S106, the subject angular velocity determination unit 603 determines (predicts) the subject angular velocity using the angular acceleration α (n).

  As described above, according to the present embodiment, by considering the value range of the angular acceleration in the prediction of the object angular velocity, the influence of the error of the movement amount on the image plane of the object detected from the temporally continuous image is suppressed. Shake correction can be performed.

  Although the present invention has been described in detail based on its preferred embodiments, the present invention is not limited to these specific embodiments, and various embodiments within the scope of the present invention are also included in the present invention. included. For example, the flowcharts described in the above-described embodiments are merely examples, and the order of processing of the flowcharts can be changed as appropriate. In addition, part of the processing of each flowchart described in the above-described embodiment can be omitted.

  Further, although the example of the lens integrated type camera has been described in the above-described embodiment, it may be an interchangeable lens type camera, and an angular velocity sensor provided in an interchangeable lens may be used.

  In the above embodiment, an example in which the follow shot assist mode is set according to the user's operation has been described, but the camera determines the movement of the camera and automatically shifts to the follow shot assist mode. You may

  In the above-described embodiment, the shift lens is used as the correction element for correcting the difference between the moving speed of the subject and the panning speed. However, the image pickup element is moved using the image pickup element as the correction element. The difference between the moving speed of the subject and the panning speed may be corrected.

Reference Signs List 100 camera 104 shift lens 107 angular velocity sensor 130 microcomputer

Claims (8)

It is an imaging device that is capable of panning, and
First calculating means for calculating an angular velocity of the subject with respect to the imaging device based on a motion vector of the subject and a movement of the imaging device based on a temporally continuous image;
A second calculation unit that calculates an angular acceleration of the subject with respect to the imaging device based on the plurality of angular velocities calculated by the first calculation unit;
A determination unit configured to determine an angular velocity of the subject with respect to the imaging device at the time of exposure according to the angular acceleration calculated by the second calculation unit;
A correction unit that moves the correction element based on the angular velocity determined by the determination unit to correct an image blur of the subject;
Equipped with
The determining unit may determine whether the angular acceleration calculated by the second calculating unit is included in a range corresponding to the angular velocity calculated by the first calculating unit. An imaging apparatus comprising: changing an angular acceleration used to determine an angular velocity of the subject.   The determination means, when the range includes the angular acceleration calculated by the second calculation means, indicates the angular acceleration calculated by the second calculation means as the subject relative to the imaging device at the time of exposure. When the angular acceleration calculated by the second calculation means is not included in the range used for determining the angular velocity, the angular acceleration set to a predetermined value is used to determine the angular velocity of the object relative to the imaging device at the time of exposure The imaging device according to claim 1, wherein the imaging device is used for   If the angular acceleration calculated by the second calculation unit is not included in the range, the determination unit determines a difference between the angular acceleration calculated by the second calculation unit and the range and the second calculation. The imaging apparatus according to claim 2, wherein the predetermined value is determined based on at least one of the number of times the angular acceleration calculated by the means is not included in the range.   The imaging apparatus according to claim 3, wherein the determination unit determines the predetermined value as a value included in the range.   The range determining unit may calculate the range based on at least one of an angle, an angular velocity, an angular acceleration, a distance, a velocity of the subject, and a moving time of the subject with respect to the imaging device. An imaging device according to any one of 1 to 4.   The imaging device according to any one of claims 1 to 5, wherein the correction element is an imaging element.   The imaging device according to any one of claims 1 to 5, wherein the correction element is a lens. It is a control method of an imaging device capable of performing panning, and
A first calculation step of calculating an angular velocity of the subject with respect to the imaging device based on a motion vector of the subject and a movement of the imaging device based on a temporally continuous image;
A second calculation step of calculating an angular acceleration of the subject with respect to the imaging device based on the plurality of angular velocities calculated in the first calculation step;
A determination step of determining an angular velocity of the subject with respect to the imaging device at the time of exposure according to the angular acceleration calculated in the second calculation step;
Correcting the image blur of the subject by moving the correction element based on the angular velocity determined in the determining step;
Equipped with
The determining step is performed on the imaging device at the time of exposure according to whether or not the angular acceleration calculated in the second calculation step is included in a range corresponding to the angular velocity calculated in the first calculation step. And controlling an angular acceleration used to determine the angular velocity of the subject.

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