Control device, imaging apparatus, control method and program

Abstract

To achieve stabilization of autofocus during zooming.SOLUTION: A control device comprises: zoom control means which controls a zoom lens to reduce a difference between the imaging size of a subject and a target size; focus control means which controls the focus lens to focus on the subject; and search control means which determines a search range of the focus position of the focus lens during the control of the zoom lens on the basis of the difference.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a control device, an imaging device, a control method, and a program. [Background technology]

[0002] In recent years, there has been an increasing need for remote cameras to automatically track and capture moving subjects in moving scenes such as lectures and sports scenes. A known technology for achieving automatic capture is to adjust the angle of view by automatically performing pan and tilt operations according to the movement of the subject to be tracked, thereby fitting the subject to be tracked within the angle of view. Another known technology is autofocus, which focuses on the subject to be tracked.

[0003] For example, the imaging device disclosed in Patent Document 1 predicts a change in subject distance from a change in face size, and sets a search direction or search range for the focusing lens position based on the prediction result, thereby enabling faster and more stable focusing in response to changes in subject distance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2009-31760 A Summary of the Invention [Problem to be solved by the invention]

[0005] In automatic photography, when fitting a tracking subject within the field of view, auto zoom is also required to keep the subject captured at a preset size. Furthermore, remote cameras also require the same image quality as cameras for video production, and auto focus stability during auto zoom is also required.

[0006] However, autofocus control during zooming is complicated, and there is a risk that the subject may go out of focus with the method disclosed in Patent Document 1. The problem to be solved by the present invention is to stabilize autofocus during zooming. [Means for solving the problem]

[0007] In order to solve the above problem, a control device according to one embodiment of the present invention comprises a zoom control means for controlling a zoom lens to reduce the difference between the shooting size of a subject and a target size, a focus control means for controlling a focus lens to focus on the subject, and a search control means for determining a search range for the in-focus position of the focus lens while controlling the zoom lens based on the difference. Effect of the Invention

[0008] According to the present invention, autofocus during zooming is stabilized. [Brief description of the drawings]

[0009] [Figure 1] 1 is a configuration diagram showing the configuration of an imaging system including an embodiment of an imaging device of the present invention. [Diagram 2] FIG. 2 is a block diagram showing an example of the functional configuration of the camera. [Diagram 3] FIG. 2 is a block diagram showing an example of the hardware configuration of the camera of the present embodiment. [Figure 4] Graph showing an example of a cam trajectory curve. [Diagram 5] FIG. 2 is a block diagram showing an example of the configuration of a client device. [Figure 6] FIG. 11 is a diagram showing an example of an application screen. [Figure 7] 11A and 11B are diagrams showing a comparative example of autofocus control during zoom control. [Figure 8] 5A to 5C are diagrams showing autofocus control during zoom control in the embodiment. [Figure 9] An image of the Focus limit table. [Figure 10] 11 is a flowchart showing a processing operation of zoom control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the present invention. The configurations of the embodiments may be appropriately modified or changed depending on the specifications and various conditions (usage conditions, usage environment, etc.) of the system and device to which the present invention is applied. The technical scope of the present invention is defined by the claims, and is not defined by the individual embodiments below. In the following description, components shown in earlier referenced drawings will be referred to as appropriate in the description of later drawings.

[0011] <Image capture system configuration> FIG. 1 is a diagram showing the configuration of an imaging system including an embodiment of an imaging device of the present invention. 1 includes a camera 101, a control terminal 102, a joystick 103, a camera controller 104, and a network 105. The camera 101 corresponds to one embodiment of the imaging device of the present invention.

[0012] The camera 101 captures images in response to a request from the control terminal 102 via the network 105, and transmits the captured image data and information related to the camera 101 via the network 105. The camera 101 may also actively transmit data to the control terminal 102 to which it is connected in advance.

[0013] The control terminal 102 is a general client terminal having a display unit such as a display and an operation unit, and specifically, for example, a personal computer (PC) or a tablet. While Fig. 1 shows, as an example, a PC in which a monitor and an input device are integrated, the control terminal 102 may be a device in which the monitor and the input device are separate.

[0014] The joystick 103 is connected to the control terminal 102 via a USB (Universal Serial Bus) or Bluetooth (registered trademark), and is used as an input device for remotely controlling the camera 101. The joystick 103 is used to realize smooth pan-tilt-zoom (PTZ) operations, which are difficult to achieve using a GUI (Graphical User Interface) on an application.

[0015] The camera controller 104 is hardware having an operation unit for operating the camera 101. The camera controller 104 is also capable of switching an automatic tracking function, which will be described later, on / off and of operating detailed settings. In Fig. 1, the camera controller 104 and the camera 101 are connected via a network 105 as an example, but the camera controller 104 and the camera 101 may be connected using a serial connection or the like.

[0016] The network 105 connects the camera 101, the control terminal 102, and the controller 104. The network 105 is realized by a plurality of routers, switches, cables, etc. that comply with a communication standard such as ETHERNET (registered trademark). Note that the network 105 may be realized by the Internet, a wired LAN (Local Area Network), a wireless LAN, a WAN (Wide Area Network), etc.

[0017] <Camera functional configuration> FIG. 2 is a block diagram showing an example of the functional configuration of the camera 101. The camera 101 includes a system control unit 201, an imaging unit 202, an image processing unit 203, a lens driving unit 204, a zoom control unit 205, a focus control unit 206, a pan driving unit 207, a tilt driving unit 208, and a pan / tilt control unit 209. These components are related to the imaging and driving of the camera 101. Furthermore, the camera 101 includes a storage unit 210, a program memory 211, automatic tracking setting data 212, zoom / focus control data 213, and a communication unit 220 as components related to data and communication.

[0018] The system control unit 201 controls the entire camera 101 and instructs the other components on how to process. The system control unit 201 analyzes camera control commands sent from the control terminal 102 and received by the communication unit 220, and executes processing according to the camera control commands. The camera control commands are classified into request commands that request the acquisition of video data or setting values, and setting commands that request the setting of setting values.

[0019] More specifically, the camera control commands mainly include commands requesting video data, commands requesting setting values ​​related to the zoom, focus, pan and tilt of the camera 101, commands requesting setting values ​​related to imaging and image processing, and commands to set the setting values. The system control unit 201 receives, for example, a request command for video data from the control terminal 102 via the communication unit 220 , and distributes the video data generated by the image processing unit 203 via the communication unit 220 .

[0020] Furthermore, the system control unit 201 receives from the control terminal 102 a request command for setting values ​​relating to imaging, such as the zoom, focus, pan / tilt, etc. of the camera 101 . Upon receiving the setting value request command, the system control unit 201 reads each setting value from the image processing unit 203, the zoom control unit 205, the focus control unit 206, and the pan / tilt control unit 209, and distributes them to the control terminal 102 via the communication unit 220.

[0021] In this specification, "setting" with respect to imaging does not only mean providing control targets for control such as PTZ operation and focus, but also means manipulating the actual lens position through control. Therefore, "setting values" with respect to imaging include not only control target values, but also current values ​​of zoom, focus, pan / tilt, etc. obtained as a result of control. Furthermore, "setting values" with respect to imaging also include the range of values ​​that can be set as control targets.

[0022] When the system control unit 201 receives a setting command for setting values ​​related to imaging, it instructs the image processing unit 203, zoom control unit 205, focus control unit 206, and pan / tilt control unit 209 to perform control based on the setting values ​​indicated by the setting command. Based on the command, image processing unit 203, zoom control unit 205, focus control unit 206 and pan / tilt control unit 209 control imaging unit 202, lens driving unit 204, pan driving unit 207 and tilt driving unit 208. As a result, the setting values ​​set by control terminal 102 are reflected in camera 101.

[0023] The image capturing unit 202 includes a lens and an image sensor, and captures an image of a subject and converts the image into an electrical signal. The image processing unit 203 performs predetermined image processing, resolution conversion processing, and compression encoding processing on the signal obtained by the imaging and photoelectric conversion in the imaging unit 202 to generate video data. The video data generated by the imaging unit 202 is distributed to the control terminal 102 via the network 105 by the communication unit 220.

[0024] The lens driving unit 204 includes a driving system for the focus lens and the zoom lens, and a motor that serves as a driving source for these driving systems, and is controlled by a zoom control unit 205 and a focus control unit 206. The zoom control unit 205 and the focus control unit 206 control the lens position based on the data of the cam locus curve included in the zoom / focus control data 213.

[0025] The pan driving unit 207 includes a mechanical driving system for performing panning operations and a motor as a driving source, and the operation of the pan driving unit 207 is controlled by a pan / tilt control unit 209 . The tilt driving unit 208 includes a mechanical driving system for performing tilt operation and a motor as a driving source, and the operation of the tilt driving unit 208 is also controlled by a pan / tilt control unit 209 .

[0026] A pan / tilt control unit 209 controls a pan driving unit 207 and a tilt driving unit 208 based on the pan / tilt setting values ​​output from the system control unit 201 to change the pan / tilt. The control of the camera 101 also includes control related to automatic shooting, and the camera 101 can automatically perform control according to the image capturing environment. For example, in autofocus control in which the camera 101 automatically focuses on a subject, the image processing unit 203 calculates an evaluation value from the contrast of an image captured by the imaging unit 202. Then, the focus control unit 206, which has acquired the evaluation value via the system control unit 201, controls the focus lens according to the evaluation value to focus on the subject.

[0027] Other automatic controls besides autofocus include automatic pan / tilt control for keeping the subject within the shooting angle of view, and zoom control for keeping the subject at a target shooting size. Automatic pan / tilt control is performed by the pan / tilt control unit 209 in accordance with instructions from the system control unit 201. Zoom control is performed by the zoom control unit 205 in accordance with instructions from the system control unit 201, and the zoom control unit 205 controls the zoom lens to reduce the difference between the shooting size of the subject and the target size. In the following description, it is assumed that pan / tilt control, zoom control, and autofocus control are all executed during automatic tracking shooting.

[0028] In addition, the image processing unit 203 can automatically control exposure (that is, aperture, shutter speed, gain, ND filter, etc.), white balance, noise reduction, gamma control, etc. The storage unit 210 stores the video data in a storage device such as a memory or storage. The memory and storage may be an internal memory and an internal storage, or may be an external memory and an external storage.

[0029] The program memory 211 is a memory that stores a camera control program, and the system control unit 201 executes various control instructions based on the camera control program stored in the program memory 211 . The automatic tracking setting data 212 is data for detailed settings related to automatic tracking, such as ON / OFF setting for whether or not automatic tracking is performed, a target size for keeping the size of the tracked subject constant, etc. The automatic tracking setting data 212 may be fixed data determined in advance, or may be variable data set via the communication unit 220. The zoom / focus control data 213 is data necessary for zoom control and autofocus control, such as a cam locus curve.

[0030] The communication unit 220 distributes the video data to the control terminal 102 via the network 105. The communication unit 220 also receives a camera control command transmitted from the control terminal 102, and outputs the command to the system control unit 201. The communication unit 220 then distributes a response to the control terminal 102 in accordance with an instruction from the system control unit 201.

[0031] 2 is an example, and multiple functional blocks may be combined into one functional block, or any functional block may be divided into blocks performing multiple functions. Furthermore, at least one of the functional blocks may be implemented as hardware. When implemented by hardware, for example, a specific compiler may be used to automatically generate a dedicated circuit on an FPGA from a program for implementing each step. FPGA stands for Field Programmable Gate Array. Also, a gate array circuit may be formed in the same manner as an FPGA and implemented as hardware, or it may be implemented by an ASIC (Application Specific Integrated Circuit).

[0032] <Camera hardware configuration> FIG. 3 is a block diagram showing an example of the hardware configuration of the camera 101 of this embodiment. The camera 101 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, and a RAM (Random Access Memory) 13. The camera 101 also includes an external memory 14, a drive unit 16, and a communication interface (I / F) 18, as well as the imaging unit 202 described above.

[0033] These elements included in the camera 101 are connected to each other via a bus 19. The portion of the camera 101 excluding the imaging unit 202 is, for example, an embedded computer, and this portion corresponds to one embodiment of the control device. The CPU 11 executes a program and an OS that causes the computer to operate as a control device. The ROM 12 stores a program (such as a BIOS) that realizes the basic functions of the computer and a camera control program, and functions as the above-mentioned program memory 211. The RAM 13 stores setting values ​​and the like used by the CPU 11, and the external memory 14 stores video data and the like. The camera 101 may include a storage device instead of or in addition to the memory.

[0034] The above-mentioned automatic tracking setting data 212 is stored in, for example, the RAM 13, and the above-mentioned zoom / focus control data 213 is stored in, for example, the ROM 12. The driving unit 16 includes a camera platform, a motor, and the like, and functions as the pan driving unit 207 and tilt driving unit 208 described above.

[0035] The communication interface 18 functions as the above-mentioned communication unit 220. The camera 101 may also include an audio output unit, an input unit such as a button, and a display unit such as a display.

[0036] <About cam path curve> Here, a cam locus curve showing the relationship between the lens position of the zoom lens and the lens position of the focus lens will be described.

[0037] FIG. 4 is a graph showing an example of a cam trajectory curve. The horizontal axis of Fig. 4 indicates the lens position of the zoom lens corresponding to the zoom magnification from minimum (WIDE end) to maximum (TELE end), and the vertical axis indicates the lens position of the focus lens corresponding to the subject distance from infinity to close range. Each cam locus curve shown in the graph of Fig. 4 indicates a cam locus for focusing an image of a subject at the same subject distance on the imaging element at each of different zoom magnifications.

[0038] Therefore, for subjects at different subject distances, the focus lens position is set on a different cam locus curve. For example, in the case of zoom lens position L shown in Fig. 4, if the subject distance is 80 cm, the focus lens position is set at the first focus lens position D1, and if the subject distance is 3 m, the focus lens position is set at the second focus lens position D2.

[0039] When zoom control is performed while maintaining a focused state on a subject at a fixed distance, the positions of the focus lens and zoom lens are controlled along the cam locus curve in Fig. 4, and so cam locus data representing the cam locus curve is required. In camera 101, the cam locus data is included in the above-mentioned zoom / focus control data 213 in the form of a table or the like, and is held in a cam locus data holding section in ROM 12, for example.

[0040] However, storing a table of cam trajectory data with fine granularity for subject distances in memory would require a huge memory capacity, so in this embodiment, only a table of cam trajectory data for some reference subject distances is stored in memory, and cam trajectory data for subject distances other than the references is calculated by interpolation processing.

[0041] <Client device configuration> Next, a client device, such as the control terminal 102 or the controller 104 shown in FIG. 1, will be described.

[0042] FIG. 5 is a block diagram showing an example of the configuration of a client device. Specific examples of the client device include the control terminal 102 and the controller 104, and are devices that allow a user to control the camera 101 with camera control commands. The client devices 102 and 104 each include a system control unit 401, a communication unit 402, a storage unit 403, an input unit 404, a program memory 405, and a display unit 406.

[0043] The system control unit 401 controls the entire client devices 102 and 104, and issues processing instructions to the other components. The system control unit 401 generates a camera control command in response to an input operation from an input unit 404 by a user or a GUI operation, and transmits the command to the camera 101 via a communication unit 402. Remote control of PTZ and the like becomes possible by transmitting a camera control command to the camera 101. In addition, transmission of a camera control command also makes it possible to switch an automatic tracking function on / off and to operate detailed settings. The system control unit 401 receives a response from the camera 101 via the communication unit 402, analyzes the response, and performs processing according to the response.

[0044] A communication unit 402 transmits camera control commands and receives various data distributed from the camera 101 . The memory unit 403 stores camera information, trace information, and the like (to be described later) in a storage device such as a memory or storage.

[0045] The input unit 404 receives user input via hardware devices such as a button, a keyboard, a mouse, or a joystick. The program memory 405 is a memory that stores a terminal control program, and the system control unit 401 executes various operations based on the terminal control program stored in the program memory 404 .

[0046] The display unit 406 displays the image from the camera 101 and the current values ​​such as the lens position of the camera 101. Note that a touch panel in which the display unit 406 and the input unit 404 are integrated may be provided. The display unit 406 also displays an application screen for performing tracking settings related to automatic tracking photography.

[0047] FIG. 6 is a diagram showing an example of an application screen. The application screen 901 is a screen on which the user sets the size and position of the tracking subject when zoom control is performed during tracking. The application screen 901 is displayed on the display unit 406 by a Web application that performs tracking settings.

[0048] An image 902 captured by the camera 101 is displayed on the application screen 901 . The application screen 901 is provided with a setting button 903 for setting the tracking function to ON / OFF, and a designation button 904 for designating whether or not to perform zoom control during tracking.

[0049] 6, the designation button 904 is in the "ON" state, which indicates "zoom control." When the designation button 904 is in the "ON" state, a slider bar 905 is activated, and the target size of the tracking subject can be set by dragging the slider bar. The slider bar 905 is provided with a reduce button 906 and an enlarge button 907. When the reduce button 906 is clicked, the target size is changed to a smaller size, and when the enlarge button 907 is clicked, the target size is changed to a larger size.

[0050] An icon 908 indicating the target size and position of the tracking subject is displayed on the captured image 902. The size of the icon 908 changes according to the target size set by the slider bar 905, the reduce button 906, and the enlarge button 907. Also, the position of the tracking target can be set and changed by dragging and dropping the icon 908.

[0051] When the tracking settings are changed on the application screen 901, the camera 101 updates the automatic tracking setting data 212. Then, automatic tracking shooting is performed according to the updated settings.

[0052] <Autofocus during zoom> Next, autofocus control during zoom control will be described. FIG. 7 is a diagram showing a comparative example of autofocus control during zoom control, and FIG. 8 is a diagram showing autofocus control during zoom control in this embodiment.

[0053] Figures 7 and 8 show a simplified version of the cam locus curve described in Figure 4, with cam locus curves corresponding to subject distances of 60 cm, 5.0 m, and infinity shown as examples. As in Figure 4, the horizontal axis of Figures 7 and 8 indicates the lens position of the zoom lens, and the vertical axis indicates the lens position of the focus lens. In the following description, the lens position of the zoom lens may be referred to as the "zoom position," and the lens position of the focus lens may be referred to as the "focus position."

[0054] 7 is an example of an image obtained with the angle of view currently captured by the camera 101, with the zoom position being closer to WIDE and the focus position being between 60 cm and 5.0 m, for example. The subject is moving in a direction away from the camera 101, for example to 5.0 m, and the subject in the image 501 appears smaller than the target size and is beginning to go out of focus. For this reason, autofocus control is required in addition to zoom control in the TELE direction.

[0055] In the comparative example, the zoom position and focus position during zoom control change along a cam locus curve 502 of the subject distance at the start of zooming, and furthermore, the focus position is moved in the vertical direction in Fig. 7 by autofocus control to search for the in-focus position. A search range 503 of the in-focus position is between the close cam locus curve and the infinity cam locus curve, and the focus lens is driven over the search range 503.

[0056] 7 are examples of images at the angle of view after zoom control. Of the three images 510, 520, and 530, the central image 510 is a case in which the focus is achieved after zooming, and the image has transitioned onto the 5.0 m cam trajectory. In contrast, of the three images 510, 520, and 530, the upper and lower images 520 and 530 are cases where the search for the in-focus position failed. In the case of the upper image 520, the focus went out during zoom control along the cam locus curve 502, and the focus position moved to the search end on the NEAR side. In the case of the lower image 530, the focus position has moved past the in-focus position to the search end on the FAR side.

[0057] In the comparative example, the autofocus search range 503 is too wide, so when the focus is significantly off, the image contrast disappears and there is no difference in the evaluation value, and it is considered that the focus lens is driven in the opposite direction to the in-focus position. In addition, there are cases where it is difficult to search for the in-focus position depending on the background of the subject, etc.

[0058] Therefore, in the camera 101 of this embodiment, as shown in FIG. 8, a search range 603 for the in-focus position is limited in autofocus during zoom control. FIG. 8 also shows an image 501 at the angle of view before zooming on the left, and the movement of the subject is the same as in FIG. Since zoom control is a control for capturing a subject at a target size, the size of the subject captured in image 501 is detected at the start of zoom control. Then, a target zoom position is calculated based on the detected subject size and the target size of the subject set in auto-tracking setting data 212. In zoom control, the zoom lens is driven toward the calculated target zoom position.

[0059] An image 510 obtained at a field angle based on a target zoom position and focus position is shown on the right side of Fig. 8. The focus position at the target zoom position is reached by searching for a focusing position by autofocus control during zoom control. In this embodiment, a search range 603 for the in-focus position is determined between a NEAR limit 601 and a FAR limit 602. The system control unit 201 determines the search range 603 based on the difference between the photographing size of the subject and the target size, and instructs the focus control unit 206. The focus control unit 206 that has been instructed to determine the search range 603 drives the focus lens within the search range 603. That is, in the case of this embodiment, the range in which the focus lens is driven by autofocus control during zoom control is narrowed to search range 603 shown in Fig. 8. As a result, the search for the in-focus position is performed within the range in which the correct direction of the in-focus position is obtained based on the contrast evaluation value. Therefore, out-of-focus as shown in Fig. 7 is avoided, and an image 510 in which the subject is in focus is obtained.

[0060] 8, the size of the subject being tracked is smaller than the target size, and the subject is moving away from the camera 101. For this reason, when the zoom lens and focus lens are driven in the TELE / FAR direction, it is expected that the in-focus position and the target size will be reached. In other words, since it is considered unnecessary to search for the in-focus position on the NEAR side of the current subject distance, it is preferable to set the cam locus curve of the current subject distance to the NEAR side limit 601.

[0061] 8, because the subject is moving away from the camera 101, there is no need to search for a focus position on the NEAR side. In contrast, if the subject is approaching the camera 101, there is no need to search for a focus position on the FAR side. Therefore, when zoom control is in the WIDE direction, the cam locus curve of the current subject distance becomes the FAR side limit 602. In the following description, of the NEAR side limit 601 and the FAR side limit 602, the one closer to the current subject distance may be referred to as the "current side limit," and the one farther may be referred to as the "changed side limit."

[0062] As described above, it is desirable that the current limit is the cam locus curve of the current object distance. And whether the current limit is the NEAR side or the FAR side depends on the direction of the zoom control. That is, when the zoom control is in the TELE direction, the search for the in-focus position is limited to the FAR side and the current limit is the NEAR limit. Also, when the zoom control is in the WIDE direction, the search for the in-focus position is limited to the NEAR side and the current limit is the FAR limit. The direction of zoom control is determined by system control unit 201 based on the difference between the shooting size of the subject and the target size, and system control unit 201 also determines whether the current limit is on the NEAR side or the FAR side. Specifically, when the shooting size is larger than the target size, system control unit 201 determines search range 603 to be on the FAR side of the current subject distance. Also, when the shooting size is smaller than the target size, system control unit 201 determines search range 603 to be on the NEAR side of the current subject distance.

[0063] In the example of FIG. 8, the FAR side limit 602 is the change side limit, and it is desirable for the change side limit to also be a cam locus curve for any of the subject distances. In this embodiment, the subject distance of the cam locus curve that is the change limit is obtained from a data table (described later) according to the difference (difference or ratio) between the current size and the target size of the tracking subject, the current subject distance, and the current zoom position. The data table is stored, for example, as a part of the zoom / focus control data 213, and is referred to by the system control unit 201. If the imaging sensor and imaging optical system are determined, the degree to which the subject distance has changed can be calculated in advance from the three elements described above, and the calculated subject distance is stored as the data table. In other words, the system control unit 201 obtains the search range 603 from a data table that is stored in advance with the subject distance and zoom position as parameters. Hereinafter, the data table will be referred to as the "Focus limit table."

[0064] FIG. 9 is an image diagram of the focus limit table. The focus limit table is stored for each current subject distance. As an example, Fig. 8 shows a focus limit table when the current subject distance is 5m and a focus limit table when the current subject distance is 2m.

[0065] Each row of the focus limit table represents a current zoom position, and each column of the focus limit table represents a difference (size difference) between the current subject size and the target size. The size difference represented by each column of the focus limit table is an example of an index showing the difference between the current subject size and the target size.

[0066] In this embodiment, an index that combines a difference and a ratio is used as the difference between the current subject size and the target size. That is, the size difference in the focus limit table is a percentage obtained by dividing the difference between the current subject size and the target size by the current subject size. Note that the index indicating the difference between the current subject size and the target size may simply be the size difference, or may be the ratio between the current subject size and the target size.

[0067] Among the columns in the Focus limit table, columns with a size difference of "0" indicate the case where the current subject size and the target size are equal, in which case zoom control is not required. In columns to the left of the column with a size difference of "0", the size difference is negative, so zoom control in the WIDE direction is required. In columns to the right of the column with a size difference of "0", the size difference is positive, so zoom control in the TELE direction is required.

[0068] Each cell in the focus limit table stores the subject distance of the cam locus curve that is the change limit. In columns to the left of the column with a size difference of "0", the focus position is searched for in the NEAR direction from the current subject distance. In columns to the right of the column with a size difference of "0", the focus position is searched for in the FAR direction from the current subject distance. In addition, the larger the size difference, the further the object distance value stored in each cell is from the current object distance, and the smaller the size difference, the closer the object distance is to the current object distance. In other words, the system control unit 201, which refers to the focus limit table, determines the search range to be narrower as the difference between the shooting size and the target size is smaller.

[0069] For example, if the current subject distance is 5m, the current zoom position is the WIDE end, and the size difference is "10%, the zoom lens and the focus lens are driven in the TELE / FAR direction. The cam locus curve that becomes the change side limit is the cam locus curve of 6m located on the FAR side, and the search range is from the cam locus curve of 5m to the cam locus curve of 6m.

[0070] For example, if the current subject distance is 2 m, the current zoom position is the TELE end, and the size difference is -30%, the zoom lens and the focus lens are driven in the WIDE / NEAR direction.Then, the cam locus curve that becomes the change side limit becomes the cam locus curve of 0.1 m located on the NEAR side, and the search range is from the cam locus curve of 2 m to the cam locus curve of 0.1 m.

[0071] Since the subject distances stored in the focus limit table are the limits of the search range for the in-focus position, it is desirable to provide a margin for the in-focus position calculated from the size difference, etc. The focus limit table shown in Fig. 9 stores subject distances with a margin.

[0072] The subject distance margin may be changed according to the zoom control speed or the aperture value if the lens has an aperture mechanism. Even if the subject distance calculated from the focus limit table is, for example, 2.4 m in the FAR direction, if the zoom control speed is high, a margin may be added and the subject distance of the change limit may be, for example, 2.6 m. The margin is specifically added by the system control unit 201. That is, the system control unit 201 determines the search range 603 to be wider as the moving speed of the zoom lens increases.

[0073] By determining the search range for the in-focus position based on the focus limit table shown in FIG. 9, out-of-focus occurrences as in the comparative example are suppressed, and degradation of image quality and loss of the subject are prevented.

[0074] <Zoom control processing> Next, the zoom control processing operation in this embodiment will be described. FIG. 10 is a flowchart showing the processing operation of the zoom control.

[0075] The processing operation shown in FIG. 10 is repeatedly executed at regular intervals while the camera 101 is tracking a specific subject. In S801, the system control unit 201 acquires the target size of the tracking subject from the automatic tracking setting data 212, and then proceeds to S802.

[0076] In S802, the image processing unit 203 detects the object to be tracked based on the video signal from the imaging unit 202, and the system control unit 201 acquires the size of the detected object (hereinafter, referred to as the detected size), and then the process proceeds to S803. In S803, the system control unit 201 calculates the above-mentioned size difference from the target size acquired in S801 and the detected size acquired in S802, and then the process proceeds to S804.

[0077] In S804, the system control unit 201 determines whether or not the angle of view needs to be adjusted by zoom control, based on the size difference calculated in S803. Specifically, if the absolute value of the size difference does not exceed the threshold, it is determined that the angle of view does not need to be adjusted (S804: No), and the processing in FIG. 10 ends. If the absolute value of the size difference exceeds the threshold, it is determined that the angle of view needs to be adjusted (S804: Yes), and the process proceeds to S805.

[0078] In S805, the above-mentioned focus limit table is referenced by the system control unit 201 based on the size difference calculated in S803, the current zoom position, and the current subject distance. Then, the change-side limit of the in-focus position search range (focus search range) is determined by the system control unit 201, and then the process proceeds to S806.

[0079] In S806, the target size acquired in S801 is compared with the detection size acquired in S802, and the zoom control direction is determined by the system control unit 20. If the target size is larger than the detection size (S806: Yes), it is found that the subject is in a direction moving away from the camera 101 and needs to be enlarged. For this reason, the process proceeds to S807, where the current limit becomes the NEAR limit, and the focus search range is restricted in the FAR direction. The system control unit 201 instructs the lens driving unit 204 to perform zoom control in the TELE direction via the zoom control unit 205 and focus control unit 206, and the process in FIG. 10 ends.

[0080] In S806, if the target size is smaller than the detected size (S806: No), it is found that the subject is approaching the camera 101 and needs to be displayed small. Therefore, the process proceeds to S808, the current limit becomes the FAR limit, and the focus search range is restricted to the NEAR direction. The system control unit 201 instructs the lens driving unit 204 to perform zoom control in the WIDE direction via the zoom control unit 205 and focus control unit 206, and the process in FIG. 10 ends.

[0081] In both S807 and S808, during zoom control, the system control unit 201 instructs the lens driving unit 204 to perform autofocus control within the focus search range via the zoom control unit 205 and the focus control unit 206. Specifically, during zoom control in the TELE direction, autofocus control is performed within the search range in the FAR direction, and during zoom control in the WIDE direction, autofocus control is performed within the search range in the NEAR direction. If the subject is already in focus when zoom control starts, autofocus control is not performed, and the zoom lens and focus lens are controlled along the cam locus curve for the current subject distance. In other words, if the subject is in focus when zoom lens control starts, the focus control unit 206 controls the focus lens along the cam locus curve and does not search for the in-focus position.

[0082] 10, the focus search range during zooming is limited based on the detected size of the subject and preset target size information. As a result, a zoom function that prevents deterioration of image quality and loss of the subject due to detection failure is realized. In the above description, an example has been shown in which the tracking settings related to automatic tracking photography are changeable by the user, but the tracking settings may be fixed. Further, in the above explanation, an example is shown in which pan / tilt control, zoom control, and autofocus control are performed, but the control device of the present invention may perform zoom control and autofocus control but not pan / tilt control.

[0083] (Other embodiments) The present invention can be embodied as, for example, a system, an apparatus, a method, a program, or a recording medium (storage medium), etc. Specifically, the present invention may be applied to a system composed of multiple devices (for example, a host computer, an interface device, a Web application, etc.), or may be applied to an apparatus composed of a single device.

[0084] The present invention can also be realized by supplying a program (computer program) that realizes one or more functions of the above-mentioned embodiments to a system or device via a network or a recording medium (storage medium). One or more processors in the computer of the system or device read and execute the program. In this case, the program (program code) itself read from the recording medium realizes the functions of the embodiment. Also, the recording medium on which the program is recorded can constitute the present invention.

[0085] In addition, not only can the functions of the embodiments be realized by the computer executing a program it has read, but the functions of the above-mentioned embodiments can also be realized by an operating system (OS) running on the computer performing some or all of the actual processing based on the instructions of the program.

[0086] Furthermore, after the program read from the recording medium is written into a memory provided on a function expansion card inserted into a computer or a function expansion unit connected to the computer, a CPU provided on the function expansion card or function expansion unit may perform some or all of the actual processing based on the instructions of the program, and the functions of the above-mentioned embodiments may be realized through this processing.

[0087] When the present invention is applied to the above-mentioned recording medium, the recording medium stores a program corresponding to the flowchart described above. The disclosure of the above embodiment includes the following configurations and methods.

[0088] (Configuration 1) a zoom control means for controlling the zoom lens to reduce the difference between a photographed size of a subject and a target size; A focus control means for controlling a focus lens to focus on the subject; a search control means for determining a search range for a focus position of the focus lens during control of the zoom lens based on the difference; A control device comprising:

[0089] (Configuration 2) 2. The control device according to configuration 1, wherein the search control means determines the search range to be on the FAR side of a current subject distance when the photographing size is larger than the target size.

[0090] (Configuration 3) 3. The control device according to configuration 1 or 2, wherein the search control means determines the search range to be on the NEAR side of a current subject distance when the photographing size is smaller than the target size.

[0091] (Configuration 4) 4. The control device according to any one of configurations 1 to 3, wherein the search control means determines the search range to be narrower as the difference is smaller.

[0092] (Configuration 5) 5. The control device according to configuration 4, wherein the search control means acquires the search range from pre-stored data having subject distance and zoom position as parameters.

[0093] (Configuration 6) 6. The control device according to configuration 4 or 5, wherein the search control means determines the search range to be wider as the moving speed of the zoom lens increases.

[0094] (Configuration 7) The control device according to any one of configurations 1 to 6, characterized in that if the subject is in focus when control of the zoom lens starts, the focus control means controls the focus lens along a cam locus curve and does not search for a focus position.

[0095] (Configuration 8) A control device according to any one of configurations 1 to 7; an imaging optical system including the zoom lens and the focus lens; an imaging means for capturing an image obtained by the imaging optical system; An imaging device comprising:

[0096] (Method 1) a zoom control step of controlling the zoom lens to reduce the difference between the photographed size of the subject and a target size; a focus control step of controlling a focus lens to focus on the subject; a search control step of determining a search range for a focus position of the focus lens during control of the zoom lens based on the difference; A control method comprising:

[0097] (Configuration 9) A program for causing an information processing device to operate as the control device according to any one of configurations 1 to 7. [Explanation of symbols]

[0098] 100...imaging system, 101...camera, 102...control terminal, 103...joystick, 104...camera controller, 105...network, 201...system control unit, 202...imaging unit, 203...image processing unit, 204...lens driving unit, 205...zoom control unit, 206...focus control unit, 207...pan driving unit, 208...tilt driving unit, 209...pan / tilt control unit, 210...storage unit, 211...program memory, 212...automatic tracking setting data, 213...zoom / focus control data, 220...communication unit, 401...system control unit, 402...communication unit, 403...storage unit, 404...input unit, 405...program memory, 406...display unit, 502...cam trajectory curve, 601...NEAR side limit, 602...FAR side limit, 603...Search range, 901...Application screen, 902...Captured image, 903...Setting button, 904...Designation button, 905...Slider bar, 906...Reduce button, 907...Enlarge button, 908...Icon

Claims

1. A zoom control means that controls the zoom lens to reduce the difference between the shooting size of the subject and the target size, A focus control means that controls the focus lens to focus on the subject, A search control means for determining the search range of the focus position of the focus lens during control of the zoom lens based on the difference, A control device characterized by comprising:

2. The control device according to claim 1, characterized in that the search control means determines the search range to be closer to the current subject distance when the shooting size is larger than the target size.

3. The control device according to claim 1, characterized in that the search control means determines the search range to be FAR (Far Arrow) from the current subject distance when the shooting size is smaller than the target size.

4. The control device according to claim 1, characterized in that the search control means determines a narrower search range as the difference is smaller.

5. The control device according to claim 4, characterized in that the search control means acquires the search range from data stored in advance with subject distance and zoom position as parameters.

6. The control device according to claim 4, characterized in that the search control means determines a wider search range as the movement speed of the zoom lens increases.

7. The control device according to claim 1, characterized in that, when the subject is in focus when the control of the zoom lens is started, the focus control means controls the focus lens along the cam trajectory curve and does not perform a search for the focus position.

8. A control device according to any one of claims 1 to 7, An imaging optical system including the zoom lens and the focus lens, An imaging means for capturing an image obtained by the aforementioned imaging optical system, An imaging device characterized by comprising:

9. A zoom control step that controls the zoom lens to reduce the difference between the shooting size of the subject and the target size, A focus control step involves controlling the focus lens to focus on the subject, A search control step in which the search range for the focus position of the focus lens during control of the zoom lens is determined based on the difference, A control method characterized by comprising:

10. A program for operating an information processing device as a control device according to any one of claims 1 to 7.

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