JP2015106116A - Imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately adjust the focus on a subject newly appearing in a picked-up image in accordance with the variation of the composition.SOLUTION: An imaging apparatus includes: an acceleration sensor 142 for detecting the direction of the variation of the composition of a picked-up image; a range-finding area setting unit 180 for setting a range-finding area 500 in an area in which a subject newly appears in the picked-up image, on the basis of the variation direction of the composition; and an AF calculation/control unit 158 for calculating the subject distance in the range-finding area 500. In this configuration, the range-finding area 500 is set in the area in which a subject newly appears in the picked-up image, so that the focus can be accurately adjusted on the subject newly appearing in the picked-up image in accordance with the variation of the composition.

Description

  The present invention relates to an imaging apparatus.

  Conventionally, for example, in Patent Document 1 below, a subject position in a photographing screen is calculated based on a photographing angle of view, a current pan / tilt position of a lens device, and a subject direction, and a distance measurement area is set at the subject position. It is described to set.

JP 2011-75832 A

  Conventionally, AF control in moving image shooting has been mainly performed by so-called contrast AF, and a scanning operation for finding a position where the contrast of an image is maximized by moving a lens is necessary. At this time, since the image quality deteriorates when the lens is frequently moved, the movement of the lens is suppressed by widening the focusing allowable amount as compared with still image shooting.

  On the other hand, in recent years, image pickup apparatuses in which an element capable of measuring a distance is arranged on the image pickup element have appeared. In such an imaging apparatus, it is possible to calculate the focus direction and the shift amount simultaneously while capturing a moving image, and it is possible to drive the lens without performing a wasteful scanning operation.

  On the other hand, the AF control algorithm is often premised on control based on contrast AF, and only the person's face detected in the screen is regarded as a distance measurement target. May not be measured with priority.

  For example, when performing panning to move the imaging device in the horizontal direction, the photographer often wants to confirm the appearance of a newly appearing subject. However, the AF area control of the imaging device is generally AF control such as center priority on the screen or face priority, and it is difficult to focus accurately on a newly appearing subject according to the composition change. there were.

  The technique described in Patent Document 1 calculates a subject position in a photographing screen based on a photographing angle of view, a pan / tilt position of a current lens device, and a subject direction, and sets a distance measuring area at the subject position. Although it is set, it is difficult to accurately focus on a newly appearing subject in accordance with a change in composition.

  Accordingly, the present invention has been made in view of the above problems, and an object of the present invention is to accurately focus on a subject newly appearing in a captured image according to a change in composition. It is another object of the present invention to provide a new and improved imaging apparatus.

  In order to solve the above-described problem, according to an aspect of the present invention, a composition change detection unit that detects a direction in which a composition of a captured image changes, and a new one in the captured image based on the direction in which the composition changes. An imaging apparatus is provided that includes a distance measurement area setting unit that sets a distance measurement area in an area where a subject appears. According to this configuration, the distance measurement area is set in an area where a new subject appears in the captured image based on the direction in which the composition changes. Accordingly, it is possible to focus on a subject that appears newly in the screen as the composition changes.

  A subject distance calculation unit that calculates a subject distance in the distance measurement region set by the distance measurement region setting unit; According to this configuration, it is possible to focus on a newly appearing subject in the composition change direction by calculating the subject distance based on the distance measurement region set to the region where the subject appears newly. .

  The composition change detection unit acquires a speed at which the composition changes, and the ranging area setting unit determines the position and size of the ranging area in the captured image according to the speed at which the composition changes. Set the shape. According to this configuration, since the position, size, or shape of the ranging area is set according to the speed at which the composition changes, the ranging area can be optimally set according to the changing speed of the composition.

  In addition, the distance measurement area setting unit sets the distance measurement area so that the higher the speed at which the composition changes, the closer the distance measurement area is to the edge of the captured image on the side where a new subject appears. . According to this configuration, the distance measurement area is set such that the distance measurement area approaches the edge of the captured image on the side where the subject appears newly as the composition change speed increases. Therefore, even when the composition change speed is high, it is possible to reliably focus on a newly appearing subject.

  Further, the distance measurement area setting unit sets the position of the distance measurement area at the center of the captured image when the speed at which the composition changes exceeds a predetermined value. According to this configuration, when the speed at which the composition changes exceeds a predetermined value, the photographer's interest moves to the entire screen. Therefore, the focus of the entire screen is set by setting the position of the distance measurement area at the center of the captured image. It becomes possible to adjust optimally.

  The subject distance calculation unit calculates a subject distance based on an evaluation value detected from each of the plurality of AF evaluation elements, and an arrangement direction of the plurality of AF evaluation elements with respect to a direction in which the composition changes. An AF evaluation element selection unit that selects a combination of the plurality of AF evaluation elements so that the directions are orthogonal to each other. According to this configuration, the combination of the plurality of AF evaluation elements is selected so that the arrangement direction of the plurality of AF evaluation elements is orthogonal to the direction in which the composition changes. The direction contrast and edge information are not convoluted, and the accuracy of AF calculation accuracy can be greatly improved.

  An exposure amount control unit that controls the exposure amount based on the subject brightness in the distance measurement area is provided. According to this configuration, it is possible to reliably suppress the occurrence of saturation and blackout in the exposure of the subject existing in the distance measurement area.

  In addition, a subject tracking unit that tracks a specific subject in the captured image and sets the distance measurement region is provided, and the distance measurement region is set by tracking the specific subject by the subject tracking unit. In addition, when the specific subject is present in the captured image, the ranging area is set by the subject tracking section without setting the ranging area by the ranging area setting section. . According to this configuration, when a specific subject is present in the captured image, the ranging area is not set by the ranging area setting section, but the ranging area is set by the subject tracking section. Accordingly, it is possible to reliably focus on a specific subject being tracked.

  Further, the composition change detection unit acquires a direction in which the composition changes from an output of the acceleration sensor. According to this configuration, the direction in which the composition changes can be acquired based on the detection of acceleration by the acceleration sensor.

  Further, the image processing apparatus includes an image vector acquisition unit that acquires a movement vector direction and a movement amount when the feature point in the captured image moves, and the composition change detection unit performs the composition based on the movement vector direction and the movement amount. Detect the changing direction. According to this configuration, by including the image vector acquisition unit that acquires the movement vector direction and the movement amount when the feature point in the captured image moves, the direction in which the composition changes based on the movement vector direction and the movement amount can be changed. It becomes possible to detect.

  Moreover, the display part which displays the said captured image and the said ranging area is provided. According to this configuration, the photographer can visually confirm the captured image and the distance measurement area displayed on the display unit.

  According to the present invention, it is possible to accurately focus on a subject that newly appears in a captured image in accordance with a change in composition.

1 is a schematic diagram illustrating a configuration of an imaging apparatus according to an embodiment of the present invention. It is a schematic diagram which shows the state which panned the imaging device from the left to the right and image | photographed a subject in order during moving image imaging from the imaging device. FIG. 3 is a schematic diagram illustrating a state in which a live view displayed on an LCD of an imaging device changes sequentially when shooting shown in FIG. 2 is performed. For comparison with the method according to the present embodiment, when the operation shown in FIG. 2 is performed with a conventional general camera, FIG. It is a schematic diagram which shows a mode that the position of a ranging area, a magnitude | size, and a shape change according to a composition change speed. FIG. 6 is a characteristic diagram quantitatively showing changes in the size and position of a distance measurement area according to the composition change speed shown in FIG. 5. It is a schematic diagram which shows arrangement | positioning of the AF evaluation element in the imaging surface of an imaging element. It is a characteristic view which shows two signals obtained from AF evaluation element. 6 is a flowchart illustrating processing when the imaging apparatus performs AF control.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

  FIG. 1 is a schematic diagram showing a configuration of an imaging apparatus 300 according to an embodiment of the present invention. The imaging device 300 includes a main body 100 and a lens 200, and has a function of capturing a moving image (and a still image). The main body 100 and the lens 200 may be configured integrally, or the lens 200 may be configured to be removable from the main body 100.

  As shown in FIG. 1, the lens 200 includes a zoom lens (group) 202, a diaphragm 204, a focus lens (group) 206, a lens CPU 210, a motor 220 for driving the diaphragm 204, and a focus lens (group). ) A / D conversion of signals indicating the positions of the motor 222 for driving 206, the drivers 224 and 226 for driving the motors 220 and 222, and the zoom lens (group) 202 and focus lens (group) 206, respectively. And an A / D converter 228, a ROM 230, and a RAM 232. The lens CPU 210 has a SIO (Serial Input / Output) 211.

  The main body 100 also includes an image sensor 110, a shutter 108 that controls the exposure time for the image sensor 110, an amplifier-integrated CDS (Correlated Double Sampling) circuit 112, an A / D converter 114, and an image input controller. 116, a nonvolatile memory 118, a compression processing unit 120, an LCD (Liquid Crystal Display) driver 124, an LCD (display unit) 126, a memory 128, a VRAM (Video Random Access Memory) 130, and a media controller 132. And a recording medium 134, a motor 136 for driving the shutter 108, a driver 138, an operation member 140, an acceleration sensor 142, a battery 144, and a control unit (DSP & CPU) 150. ing.

  The control unit 150 includes an AE / AWB / AF evaluation value calculation circuit 152, an appropriate AWB calculation unit 154, an image processing unit 156, an AF calculation / control unit 158, an AE calculation / control unit 160, and an image vector acquisition unit. 170, GUI management unit 172, timing generator 174, I / O (Input / Output) 176, SIO (Serial Input / Output) 178, ranging area setting unit 180, subject tracking unit 182, AF And an evaluation element selection unit 184.

  The zoom lens 202, the diaphragm 204, and the focus lens 206 are driven via motors 220 and 222 controlled by the drivers 224 and 226 based on a command from the lens CPU 210. The zoom lens 202 is a lens that moves back and forth in the optical axis direction and continuously changes the focal length. The diaphragm 204 adjusts the amount of light incident on the image sensor 110 when capturing an image. The focus lens 206 is moved back and forth in the optical axis direction and adjusts the focus of the subject image formed on the image sensor 110.

  The image sensor 110 is an element for converting light incident through the zoom lens 102, the diaphragm 104, the focus lens 108, and the shutter 108 into an electrical signal.

  As the image sensor 110, a CCD (Charge Coupled Devices) element, a CMOS (Complementary Metal Oxide Semiconductor) element, and other image sensors can be used. Since the CMOS element can convert the image light of the subject into an electric signal at a higher speed than the CCD element, it is possible to shorten the time from when the subject is imaged to when the image is combined.

  The CDS circuit 112 is a circuit in which a CDS circuit that is a kind of sampling circuit that removes noise from the electrical signal output from the image sensor 110 and an amplifier that amplifies the electrical signal after removing noise are integrated. . In the present embodiment, a circuit in which the CDS circuit and the amplifier are integrated is used. However, the CDS circuit and the amplifier may be configured as separate circuits.

  The A / D converter 114 converts the electric signal generated by the image sensor 110 into a digital signal, and generates raw image data (raw data, image data). The image input controller 116 controls input of raw image data (image data) generated by the A / D converter 114 to the memory 128.

  The compression processing unit 120 performs a compression process for compressing image data output from the image sensor 110 into image data of an appropriate format. The image compression format may be a reversible format or an irreversible format. As an example of an appropriate format, it may be converted into a JPEG (Joint Photographic Experts Group) format or JPEG2000 format.

  The LCD 126 performs live view display before performing an imaging operation, various setting screens of the imaging apparatus 300, display of captured images, and the like. Display of image data and various types of information of the imaging apparatus 300 on the LCD 126 is performed via the LCD driver 124.

  The memory 128 temporarily stores captured images. The memory 128 has a storage capacity sufficient to store a plurality of images. Reading and writing of images to and from the memory 128 is controlled by the image input controller 116.

  The VRAM 130 holds the contents displayed on the LCD 126, and the resolution and the maximum number of colors of the LCD 126 depend on the capacity of the VRAM 136.

  The recording medium 134 records captured images. Input / output to / from the recording medium 134 is controlled by the media controller 132. As the recording medium 134, a memory card, which is a card-type storage device that records data in a flash memory, can be used.

  The control unit 150 issues a signal system command to the image sensor 110, the CDS circuit 112, or the like, or issues an operation system command according to the operation of the operation member 140 (such as a shutter button). In the present embodiment, only 150 control units are included, but the signal system command and the operation system command may be executed by separate CPUs.

  The AE / AWB / AF evaluation value calculation circuit 152 of the control unit 150 uses an AE evaluation value as exposure amount information and an AWB evaluation value that is an evaluation value of auto white balance (AWB) from image data output from the image sensor 110. Value, and an AF evaluation value for evaluating the autofocus (AF) of the subject. The appropriate AWB calculation unit 154 calculates an appropriate auto white balance based on the AWB evaluation value. The image processing circuit 156 performs processing such as light amount gain correction, image edge processing (outline enhancement processing), and white balance adjustment on the image data output from the image sensor 110.

  The AF calculation / control unit 158 performs distance measurement using contrast AF or image plane phase difference AF, and controls the focus lens 108. At this time, the AF calculation / control unit 158 performs distance measurement using the distance measurement region 500 set by the distance measurement region setting unit 180. The AE calculation / control unit 160 performs AE calculation of the captured image, calculates the exposure amount, and controls the aperture 204 and the shutter 108 to control the exposure amount. The image vector acquisition unit 170 acquires the motion vector of the image by comparing the images of adjacent frames, and detects the moving direction of the imaging device 300. The GUI management unit 172 receives an operation of the operation member 140 by the user. The control unit 150 controls the user according to the operation according to the operation of the operation member 140 detected by the GUI management unit 172.

  The distance measurement area setting unit 180 sets the distance measurement area 500 in an area where a new subject appears in the captured image based on the direction in which the composition acquired by the acceleration sensor 142 or the image vector acquisition unit 170 changes. In addition, the distance measurement area setting unit 180 sets the position, size, or shape of the distance measurement area 500 in the captured image according to the change rate of the composition acquired by the acceleration sensor 142 or the image vector acquisition unit 170. .

  The subject tracking unit 182 tracks a specific subject in the captured image and sets a distance measurement area. For example, in the case of performing face detection, the subject tracking unit 182 sets a distance measurement area so as to track the movement of the detected face image. The subject tracking unit 182 tracks a specific subject specified by the operation of the operation member 140 by the user, and sets a distance measurement area.

  The AF evaluation element selection unit 184 is arranged so that the arrangement direction of two AF evaluation elements 110a described later is orthogonal to the direction in which the composition acquired by the acceleration sensor 142 or the image vector acquisition unit 170 changes. A combination of two AF evaluation elements 110a is determined.

  The timing generator 174 inputs a timing signal to the image sensor 110. That is, the drive of the image sensor 110 is controlled by the timing signal from the timing generator 174. The timing generator 174 can cause the image sensor 110 to have an electronic shutter function by causing image light from a subject to enter during the time that the image sensor 110 is driven.

  The I / O 176 sends a command from the control unit 150 to the driver 138. As a result, the motor 136 is driven by the driver 138 and the shutter 108 is driven. The SIO 178 exchanges signals with the SIO 211 of the lens CPU 210 and sends a command from the control unit 150 to the lens CPU 210. Further, the SIO 178 receives a command from the lens CPU 210. The acceleration sensor 142 detects the movement of the imaging device 300 from the acceleration of the imaging device 300.

  When displaying a moving image recording or live view before shooting with a digital camera or a camcorder, the composition is frequently changed in order to check the situation outside the screen or to match the movement of the subject. However, as described above, the distance calculation processing is generally performed with priority given to the subject in the center of the screen or the subject in the vicinity of the camera or the tracking of the detected human face. Is not implemented.

  In the present embodiment, when a composition change such as panning is detected, the subject newly appearing in the screen in the moving direction is intensively measured. The highest concern of the photographer during the composition change is the appearance of the subject appearing in the moving direction. Therefore, by focusing on a subject that appears newly in the screen in the moving direction, it is possible to focus on the subject that the photographer is most interested in.

  In the imaging apparatus 300 of the present embodiment, distance measurement is performed using image plane phase difference AF as an example. In contrast AF, control is performed to return the focus lens to the peak position after the focus lens passes the contrast peak position (so-called hill-climbing control). For this reason, in contrast AF, the movement of the lens for peak detection is troublesome, and the AF operation is often controlled more conservatively during moving image display than during still image shooting regardless of whether or not there is a composition change. Further, in order to avoid the troublesome movement of the lens, in the case of contrast AF, when a composition change occurs (when the camera is moved by panning or the like), AF operation is not performed and the composition is confirmed (camera AF operation was performed for the first time after the camera stopped. However, in the case of the image plane phase difference AF control, there is no troublesome movement of the lens as in contrast AF, so that it is not necessary to perform an annoying lens movement even during moving image display. Therefore, by using the image plane phase difference AF control, the AF operation can be performed without causing the troublesome movement of the lens during moving image shooting, and it is easy to meet the demands of the photographer.

  For this reason, in the present embodiment, in the imaging apparatus in which the photographer can change the composition, the AF control is performed with an emphasis on the region that appears in accordance with the composition change by performing distance measurement using the image plane phase difference AF. Note that it is also effective to use contrast AF if the focus lens drive control can be performed at such a high speed that the photographer does not feel the trouble of moving the lens.

  FIG. 2 shows a state in which the imaging apparatus 300 is panned from left to right (in the direction of arrow A1) and the subjects 400, 410, 420, and 430 are sequentially imaged from the imaging apparatus 300 during moving image imaging. It is a schematic diagram. FIG. 3 is a schematic diagram illustrating a state in which a live view (that is, a moving image captured by the imaging apparatus 300) displayed on the LCD 126 of the imaging apparatus 300 sequentially changes when the imaging illustrated in FIG. 2 is performed. is there.

  As shown in FIG. 3, in the imaging apparatus 300 according to the present embodiment, when panning is performed and the composition is gradually changed, a ranging area (AF area) 500 moves in the moving direction of the camera within the screen. Normally, when a photographer performs panning, there are many subjects that are interested in the moving direction of the imaging apparatus 300. Taking the state of FIG. 3B as an example, it is assumed that the photographer is interested in the subject 420 existing in the moving direction of the image by panning. Therefore, as shown in FIG. 3B, by moving the ranging area 500 in the panning direction within the screen, the photographer can focus on the subject 420 that is most interested in, The subject 420 can be photographed clearly. As described above, according to the present embodiment, the distance measurement area 500 is set with a point newly appearing in the screen as the priority area when the composition is gradually changed, such as vanning or tilt. This makes it possible to focus on the subject that the photographer is most interested in and capture a clear image.

  On the other hand, FIG. 4 is a schematic diagram showing a camera ranging area 600 in an image when the operation shown in FIG. 2 is performed with a conventional general camera for comparison with the method according to the present embodiment. is there. As shown in FIG. 4, the distance measuring area 600 is generally arranged at the center of the screen. In this configuration, as shown in FIG. 4, even if the photographer pans the camera from left to right and changes the composition, the position setting of the ranging area 600 relative to the screen does not change. That is, the distance measuring area 600 is always fixed at the center position with respect to the screen.

  For cameras equipped with a face detection function, the detected face area can be set as a distance measurement area, and a specific subject can be specified by touching the screen. A distance measurement area is set, and tracking of these distance measurement areas is performed. However, even in this case, since the ranging area is not moved in the moving direction of the camera, it is not assumed that the ranging area is changed according to the movement of the camera such as panning.

  In FIG. 3, panning in the right direction is shown, but if the panning is in the left direction, the ranging area 500 is set on the left side of the screen (near the left side of the screen). Similarly, in the case of tilting in the upward direction, the ranging area 500 is set near the upper side of the screen, and in the case of tilting in the downward direction, the ranging area 500 is set near the lower side of the screen.

  The composition change shown in FIG. 3 can be detected using the output of the acceleration sensor 142 mounted on the imaging apparatus 300. According to the acceleration sensor 142, the panning or tilt operation direction of the imaging apparatus 300 can be detected. The ranging area setting unit 180 of the control unit 150 moves the ranging area 500 in the operation direction of the imaging apparatus 300 detected by the acceleration sensor 142.

  Also, the composition change shown in FIG. 3 can be detected by the image vector acquisition unit 170 of the control unit 150. In this case, the image vector acquisition unit 170 extracts the feature points in the image, and when the movement vector direction and the movement amount of the current frame and the previous frame are aligned on the entire screen, the movement vector direction and the movement amount. The composition change can be detected based on the above. The ranging area setting unit 180 of the control unit 150 moves the ranging area 500 in the operation direction of the imaging apparatus 300 detected by the image vector acquisition unit 170. As described above, the acceleration sensor 142 and the image vector acquisition unit 170 function as a composition change detection unit that detects the direction in which the composition of the captured image changes. The acceleration sensor 142 and the image vector acquisition unit 170 can also detect the composition change speed.

  The AF tracking function is given priority when the AF tracking function for a specific face is detected by the subject tracking unit 182 or when the AF tracking function for the subject specified by the photographer is operating. Then, the ranging area 500 is set by AF tracking.

  In the setting of the distance measurement area 500 according to the composition change, attention is paid to the subject existing in the distance measurement area 500. Therefore, in the exposure control of the distance measurement area 500, the AE calculation / control unit 160 is at least saturated. The exposure is controlled so as not to cause blackout.

  It is desirable to variably control the location and size of the distance measurement area 500 according to the composition change speed. Until the composition change speed reaches a predetermined amount, the distance measurement area 500 is set specifically for an area that appears in the screen in the moving direction of the imaging apparatus 300. When the composition change speed is further increased, the photographer's interest is expected to be transferred to the entire screen. Therefore, the distance measurement area 500 is returned to the center of the screen again, and distance measurement is performed with the center weight.

  FIG. 5 is a schematic diagram showing how the position, size, and shape of the ranging area 500 change according to the composition change speed. FIG. 5A shows a case where there is no composition change. In this case, since the normal AF operation is performed, the distance measurement area 500 is set to be focused on the center of the screen, and the shape of the distance measurement area 500 is a horizontally long elliptical shape in accordance with the horizontally long screen. Ranging is performed.

  FIG. 5B to FIG. 5E show a case where the composition changes from left to right due to panning. FIG. 5B shows the case where the composition change amount is small, that is, the composition change speed is small. In this case, the distance measurement area 500 moves in the composition moving direction (moving direction of the imaging apparatus 300). The shape of the distance measurement area 500 is a circle, and the size (area) of the distance measurement area 500 is smaller than that in FIG.

  FIG. 5C shows a case where the composition change amount is larger than that in FIG. 5B, that is, a case where the composition change speed is large. In this case, the distance measurement area 500 is set at a position closer to the composition moving direction than FIG. The shape of the distance measurement area 500 is a vertically long ellipse. Thereby, the ranging area 500 is set to a range along the right side of the screen.

  FIG. 5D shows a case where the composition change amount is larger than that in FIG. 5C, that is, a case where the composition change speed is high. As shown in FIG. 5D, when the composition change amount further increases, the ranging area 500 moves to the center side of the screen as compared with FIG. 5C, and the same position and size as in FIG. 5B. Is set.

  FIG. 5E shows a case where the composition change amount is larger than that in FIG. 5D, that is, a composition change speed is large. As shown in FIG. 5E, when the composition change amount further increases, the distance measurement area 500 moves to the center of the screen and is set to the same position and size as in FIG.

  FIG. 6 is a characteristic diagram quantitatively showing changes in the size and position of the distance measurement area 500 in accordance with the composition change speed shown in FIG. The upper characteristic of FIG. 6 shows the movement of the center position of the distance measuring area 500 according to the panning speed. As shown in the upper characteristic of FIG. 6, as the panning speed for the right movement increases, the distance measurement area 500 moves from the center position of the screen to the right end position, and when the panning speed for the right movement further increases, Move to the center of the screen. Similarly, as the panning speed for left movement increases, the ranging area 500 moves from the screen center position to the left end position, and when the panning speed for left movement further increases, the ranging area 500 moves to the screen center position.

  Further, the lower characteristic of FIG. 6 shows a change in the flatness ratio of the distance measurement area 500 according to the panning speed. As shown in the lower characteristic of FIG. 6, as the panning speed for the right movement increases, the shape of the ranging area 500 changes from a laterally extending ellipse to a perfect circle, and when the panning speed for the right movement further increases, the distance measurement The shape of the region 500 changes to a horizontally expanded ellipse. Similarly, as the panning speed for the left movement increases, the shape of the ranging area 500 changes from a horizontally-spreading ellipse to a perfect circle, and when the panning speed for the left movement further increases, the shape of the ranging area 500 increases laterally. It changes into an ellipse.

  In general, AF detection is performed in two directions, a horizontal direction and a vertical direction. When panning in the horizontal direction, since the contrast and edge information in the horizontal direction are convoluted, the AF calculation accuracy decreases. Therefore, when the imaging apparatus 300 performs horizontal movement, it is appropriate to perform AF calculation that places importance on the vertical direction. In addition, when the imaging apparatus 300 performs vertical movement, it is appropriate to perform AF calculation that places importance on the horizontal direction.

  For this reason, in this embodiment, a pair of AF evaluation elements when performing image plane phase difference AF is two AF evaluation elements arranged in a direction orthogonal to the moving direction of the imaging apparatus 300. FIG. 7 is a schematic diagram showing the arrangement of the AF evaluation elements 111 on the imaging surface of the imaging element 110. The AF evaluation element 111 includes a part of pixels arranged in a matrix on the imaging surface.

  In the image plane phase difference AF, a pair P is formed by two arbitrary AF evaluation elements 111a and 111b, and the image plane phase difference is obtained. The two AF evaluation elements 111a and 111b are provided with slits S that transmit light only to a part of a normal pixel, and the slits S provided in the two AF evaluation elements 111a and 111b are The two AF evaluation elements 111a and 111b are arranged at positions symmetrical with respect to the center line C located in the middle.

  Here, FIG. 7A shows a state where the imaging device 100 is stationary, that is, a state where panning is not performed. In this case, as in FIG. 3A, the ranging area 500 is arranged at the center of the screen. As shown in FIG. 8, the signal a obtained from the plurality of AF evaluation elements 111a and the signal b obtained from the plurality of AF evaluation elements 111b are output with a phase shift according to the focus shift. Therefore, the focus lens 206 can be driven to the in-focus position by driving the focus lens 206 so that the phase shift between the signal a and the signal b becomes a predetermined value. A known method can be used for such image plane phase difference AF control.

  FIG. 7B shows a state where the imaging apparatus 300 is panning in the right direction. When the imaging apparatus 300 pans in the right direction, the ranging area 500 moves to the right side (arrow direction) of the screen, as in FIG. At this time, as shown in FIG. 7C, the pair P of the AF evaluation element 111a and the AF evaluation element 111b that performs the image plane phase difference AF is formed by two AF evaluation elements 111a and 111b arranged in the vertical direction of the screen. Composed. As a result, the moving direction of the image pickup apparatus 300 and the arrangement direction of the AF evaluation elements 111a and 111b that perform the image plane phase difference AF are orthogonal to each other, so that it is possible to perform AF calculation with an emphasis on the vertical direction. Accordingly, the contrast and edge information in the horizontal direction are not convoluted during AF calculation, and the accuracy of AF calculation accuracy can be greatly improved. As described above, since the pair of AF evaluation elements 111a and 111b having the slits S shown in FIG. 7A is arranged in the horizontal direction (horizontal direction), the light beams different in the left and right directions are captured, and the horizontal direction Suitable for evaluating phase difference. On the other hand, since the pair of AF evaluation elements 111a and 111b having the slits S shown in FIG. 7C are arranged in the vertical direction (vertical direction), different light fluxes are detected in the vertical direction, and the phase difference in the vertical direction is detected. It is suitable for evaluating. Accordingly, by selecting a pair of AF evaluation elements 111a and 111b arranged in the horizontal direction or a pair of AF evaluation elements 111a and 111b arranged in the vertical direction according to the direction of composition change, the accuracy of AF calculation accuracy is improved. Can be greatly improved. Since both the horizontal phase difference evaluation and the vertical phase difference evaluation cannot be performed on the same pixel pair, the horizontal phase difference evaluation and the vertical phase difference evaluation are performed. The pairs are provided separately and are arranged over the entire imaging surface of the imaging device 110.

  Next, a processing procedure in the imaging apparatus 300 according to the present embodiment will be described. FIG. 8 is a flowchart illustrating processing when the imaging apparatus 300 performs AF control. First, in step S10, a change in composition is detected. In the next step S12, it is determined whether or not the parallel movement of the imaging apparatus 300 is performed at a predetermined speed or higher. If the parallel movement is not performed at a predetermined speed or higher in step S12, the process proceeds to step S14, and normal AF calculation is performed. In this AF calculation, distance measurement is performed using image plane phase difference AF. On the other hand, if the parallel movement is performed at a predetermined speed or higher in step S12, the process proceeds to step S16.

  In step S16, it is determined whether or not a specific subject is being tracked. If the specific subject is not being tracked, the process proceeds to step S18 and subsequent steps. In step S18, the composition moving speed is calculated, and in the next step S20, the position, size, and shape of the distance measuring area 500 are determined. The position, size, and shape of the ranging area 500 are determined based on the characteristics shown in FIG. In the next step S22, weighting in the horizontal / vertical direction of AF detection is determined.

  In the next step S24, an AF calculation for composition change is performed in consideration of the weighting determined in step S22 based on the ranging area 500 determined in step S20. In this AF calculation, distance measurement is performed using image plane phase difference AF.

  After steps S14 and S24, the process proceeds to step S26. In step S26, the lens movement amount is calculated based on the AF calculation results in steps S14 and S24. In the next step S28, lens movement control is performed based on the lens movement amount calculated in step S26. Specifically, the lens movement amount is sent from the SIO 178 of the control unit 150 to the SIO 211 of the lens CPU 210, and the lens CPU 210 drives the motor 222 via the driver 226, thereby driving the focus lens 206.

  As described above, when setting the position, size, and shape of the distance measurement area 500 in accordance with the composition change, attention is paid to the subject existing in the distance measurement area 500. Then, control is performed so that at least the subject existing in the distance measuring area 500 does not cause saturation or blackout. For this reason, in step S30, the exposure amount of the ranging area 500 is verified. In the next step S32, it is determined whether or not there is a defect in the exposure of the distance measuring area 500. If there is a defect in the exposure of the distance measuring area 500, the process proceeds to step S34, and the exposure correction amount is reflected in the frame of the next moving image. On the other hand, if there is no defect in the exposure of the distance measuring area 500, the process returns to the start (RETURN).

  If a specific subject is being tracked in step S16, the process proceeds to step S36. In step S36, it is determined whether or not the tracked subject exists in the screen. If the tracked subject does not exist in the screen, the processes in and after step S18 are performed. On the other hand, when the tracked subject exists in the screen, the process proceeds to step S38, and a calculation for measuring the distance of the tracked subject is performed. After step S38, the process after step S26 is performed.

  In the present embodiment, in the image plane phase difference AF, an example in which the distance measurement area 500 is moved in the moving direction of the imaging device 300 in the screen in accordance with the composition change due to the movement of the imaging device 300 has been described. The AF can be configured similarly. Even when the present invention is applied to an imaging apparatus that performs contrast AF, it is possible to focus on a subject that newly appears in the screen by moving the distance measuring area 500 in the moving direction of the imaging apparatus 300 within the screen as the composition changes. It is possible to burn.

  In the present embodiment, the imaging apparatus 300 that mainly captures moving images has been described as an example. However, the present embodiment can also be applied to an imaging apparatus that captures still images. Even in an imaging apparatus that captures a still image, the focus is focused on a subject that newly appears in the screen by moving the distance measuring area 500 in the moving direction of the imaging apparatus 300 in the screen as the composition changes. Is possible.

  As described above, according to the present embodiment, the distance measurement area 500 is moved in the moving direction of the image pickup apparatus 300 within the screen as the image pickup apparatus 300 is moved. It is possible to focus on the subject appearing in. Therefore, it is possible to focus on the subject that is most interesting to the photographer.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 300 Imaging device 142 Acceleration sensor 158 AF calculation and control part 170 Image vector acquisition part 180 Distance measurement area setting part 182 Subject tracking part 184 AF evaluation element selection part

Claims (11)

A composition change detector that detects a direction in which the composition of the captured image changes;
A distance measurement area setting unit that sets a distance measurement area in an area where a new subject appears in the captured image based on a direction in which the composition changes;
An imaging apparatus comprising:   The imaging apparatus according to claim 1, further comprising a subject distance calculation unit that calculates a subject distance in the distance measurement region set by the distance measurement region setting unit. The composition change detection unit acquires a speed at which the composition changes,
The imaging apparatus according to claim 1, wherein the ranging area setting unit sets a position, a size, or a shape of the ranging area in the captured image according to a speed at which the composition changes.   The ranging area setting unit sets the ranging area so that the ranging area approaches the edge of the captured image on the side where a new subject appears as the speed at which the composition changes increases. The imaging apparatus according to claim 3, wherein the imaging apparatus is characterized.   The imaging apparatus according to claim 3, wherein the ranging area setting unit sets the position of the ranging area at the center of the captured image when a speed at which the composition changes exceeds a predetermined value. . The subject distance calculation unit calculates a subject distance based on an evaluation value detected from each of a plurality of AF evaluation elements,
An AF evaluation element selection unit that selects a combination of the plurality of AF evaluation elements so that an arrangement direction of the plurality of AF evaluation elements is orthogonal to a direction in which the composition changes. The imaging device according to claim 2.   The imaging apparatus according to claim 1, further comprising an exposure amount control unit that controls an exposure amount based on subject brightness in the distance measurement area. A subject tracking unit that tracks a specific subject in the captured image and sets the ranging area;
When the distance measurement area is set by tracking the specific object by the object tracking section and the specific object exists during the imaging, the distance measurement area setting section performs the measurement. The imaging apparatus according to claim 1, wherein the distance measurement area is set by the subject tracking unit without setting the distance area.   The imaging apparatus according to claim 1, wherein the composition change detection unit acquires a direction in which the composition changes from an output of an acceleration sensor. An image vector acquisition unit that acquires a movement vector direction and a movement amount when a feature point in the captured image moves;
The imaging apparatus according to claim 1, wherein the composition change detection unit detects a direction in which the composition changes based on the movement vector direction and a movement amount. The imaging apparatus according to claim 1, further comprising a display unit that displays the captured image and the ranging area.

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