JP2010056738A - Image capturing apparatus and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image capturing apparatus which performs stable detection operations for feature regions of an object even during zoom operation. <P>SOLUTION: The image capturing apparatus has a control means 115 for controlling a zoom lens 102 which changes a magnification for an object, and a detection means 112 for detecting feature regions of the object. The control means 115 controls a moving speed of the zoom lens 102 so as to decrease or stop if feature regions of the object are not detected by the detection means 112 during moving of the zoom lens. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an imaging apparatus such as a digital camera or a video camera and a control method for the imaging apparatus, and more particularly to an imaging apparatus capable of detecting a characteristic part of a subject such as face detection and a control method for the imaging apparatus.

  Some imaging devices such as digital cameras and video cameras detect a person's face area when the subject is a person, and perform focus adjustment and exposure control based on the detected face area.

  In conventional face detection, the face area is detected based on the captured video signal. However, the face area cannot be detected or the detection accuracy deteriorates depending on the face area detection method or imaging environment. It has become.

Therefore, we proposed an imaging device that increases the accuracy of face detection by controlling the zoom lens to the wide-angle side when face detection is performed and by widening the depth of field than when face detection is not being performed. (Patent Document 1).
JP 2006-033439 A

  In Patent Document 1, the zoom lens is controlled to the wide-angle side in order to increase the accuracy of face detection. However, it relates to face detection at a certain angle of view, and does not particularly describe face detection during a zoom operation. .

  During the zoom operation, the captured image flows around the periphery of the image. For this reason, face detection becomes impossible or face detection accuracy decreases, for example, not only the face frame indicating the detected face area is switched between display and non-display, but also the focus adjustment or focusing on the detected face is performed. When exposure control is performed, hunting occurs.

  This depends on the driving speed of the zoom lens. The higher the driving speed, the greater the influence. In moving image shooting with a video camera or the like, unlike still image shooting with a digital camera or the like, an image during zoom operation is also recorded, so it is desirable that stable face detection operation can be performed even during zoom operation.

  Therefore, an object of the present invention is to provide an imaging apparatus and a control method for the imaging apparatus that can enable a stable detection operation of a characteristic part of a subject even during a zoom operation for moving image shooting.

  In order to achieve the above object, an imaging apparatus according to the present invention includes a detection unit that detects a characteristic part of a subject, and a control unit that controls movement of a zoom lens that changes the magnification of the subject. The moving speed of the zoom lens is controlled to be reduced or stopped when the characteristic portion of the subject is not detected by the detecting means during the movement of the zoom lens.

  An imaging apparatus control method according to the present invention includes a control step for controlling a zoom lens that changes a magnification of a subject, and a detection step for detecting a characteristic part of the subject, wherein the control step is during movement of the zoom lens. When the characteristic part of the subject is not detected in the detection step, the zoom lens driving speed is controlled to be reduced or stopped.

  According to the present invention, the detection accuracy can be improved by reducing the influence of the flow of the captured image during the zoom operation on the detection of the characteristic part of the subject. The detection operation of the characteristic part is possible.

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

(First embodiment)
FIG. 1 is a block diagram for explaining an apparatus configuration of an imaging apparatus according to the first embodiment of the present invention.

  As shown in FIG. 1, the imaging apparatus of the present embodiment includes a first fixed lens group 101, a zoom lens 102 that changes the magnification of a subject, a diaphragm 103, a second fixed lens group 104, and a focus lens 105. ing. The focus lens 105 is a lens group that has both a focus adjustment function and a so-called competition function that corrects movement of the focal plane due to zooming.

  The zoom lens drive source 110 moves the zoom lens 102 and the focus lens drive source 111 moves the focus lens 105. The zoom lens drive source 110 and the focus lens drive source 111 each have a motor and a driver. The zoom lens driving source 110 and the focus lens driving source 111 move each lens based on the target position and driving speed calculated by the camera control unit 115. In other words, the camera control unit 115 obtains the target position and driving speed and controls the movement of each lens.

  The image sensor 106 is configured by, for example, a CMOS sensor, a CCD sensor, or the like. The camera signal processing circuit 107 converts the output signal of the image sensor 106 into a signal corresponding to the display device 108 and the recording device 109. The recording device 109 records a moving image or a still image, and a magnetic tape, a semiconductor memory, a DVD, or the like is used as a recording medium.

  The camera control unit 115 calculates target positions of the zoom lens 102 and the focus lens 105 based on an output signal from the zoom switch 116, and controls the zoom lens drive source 110 and the focus lens drive source 111 to move each lens. Control as follows. A zoom switch 116 for moving the zoom lens 102 in the wide direction and the tele direction is connected to the camera control unit 115. The zoom switch 116 has a circuit configuration in which the voltage changes in response to the pressing.

  The camera control unit 115 detects the voltage change when the zoom switch 116 is operated, and determines at what zoom speed of the variable speed zoom the zoom lens 102 is moved according to the voltage change. The camera control unit 115 also controls the zoom lens moving speed according to the face detection result in the face detection processing circuit 112. Further, the camera control unit 115 controls the focus lens driving source 111 according to the face detection result, and performs focus adjustment by moving the focus lens 105.

  The face detection processing circuit 112 extracts the characteristic part of the subject from the video signal that is the output of the camera signal processing circuit 107 and detects the face area and the face size of the subject. The camera control unit 115 determines the driving speed of the zoom lens 102 according to the face detection result of the face detection processing circuit 112 and controls the zoom lens driving source 110. In the present embodiment, the face detection processing circuit 112 is described as having a configuration different from that of the camera control unit 115, but the face detection processing function can also be realized by software in the camera control unit 115. .

  The face frame display signal generation circuit 114 generates a signal of a display frame such as a face frame according to the detection result of the face detection processing circuit 112, and the signal of the display frame is generated by the signal synthesis processing circuit 113 by the camera signal processing circuit. It is combined with the video signal output from 107 and output to the display device 108. The user can know the face detection result based on whether or not the display frame is displayed on the display device 108.

  Next, the movement speed control of the zoom lens when a zoom operation is performed during moving image shooting face detection will be described with reference to FIG. 2 is executed by the CPU or the like of the camera control unit 115 by loading a program stored in a ROM, hard disk, or the like (not shown) into the RAM.

  First, in step S101, the camera control unit 115 determines whether or not the zoom lens 102 is moving.

  If the zoom lens 102 is moving, the camera control unit 115 proceeds to step S102. If the zoom lens 102 is not moving, the camera control unit 115 does not need to change the moving speed of the zoom lens 102 and ends the process. To do.

  In step S102, the camera control unit 115 determines whether or not the face area of the subject is detected in the video signal from the face detection processing circuit 112.

  If the camera control unit 115 determines that no face area has been detected, the camera control unit 115 determines that the face area has failed to be detected, and proceeds to step S103. If the camera control unit 115 determines that the face area has been detected, it can be said that the detection accuracy of the face area is guaranteed even with the current moving speed of the zoom lens 102. The process ends without changing.

  In step S <b> 103, the camera control unit 115 controls the zoom lens driving source 110 to decelerate the moving speed of the zoom lens 102, and ends the process. In the present embodiment, when the face area detection fails, the moving speed of the zoom lens 102 is set to be slower than that during face detection. However, the moving speed of the zoom lens 102 is set to 0 and the zoom lens 102 is moved. 102 may be stopped.

  As described above, in this embodiment, when the face area cannot be detected during the zoom operation for moving image shooting, the driving speed of the zoom lens 102 is reduced or stopped. This makes it possible to improve the detection accuracy of the face area by reducing the influence on the face detection due to the flow of the captured image during the zoom operation for moving image shooting, and the stable face area even during the zoom operation for moving image shooting Can be detected.

(Second Embodiment)
Next, with reference to FIG.3 and FIG.4, the imaging device which is the 2nd Embodiment of this invention is demonstrated.

  FIG. 3 is a block diagram for explaining a device configuration of an imaging apparatus according to the second embodiment of the present invention. In addition, about the part which overlaps with the said 1st Embodiment, the same code | symbol is attached | subjected to a figure and the description is abbreviate | omitted.

  As shown in FIG. 3, the imaging apparatus of the present embodiment includes a distance measuring sensor 117 for detecting a distance to the subject.

  The camera control unit 115 determines the target position of the focus lens 105 based on the distance to the subject measured by the distance measuring sensor 117 and controls the focus lens drive source 111. In the present embodiment, the distance measurement sensor 117 will be described as an external measurement phase difference detection method provided independently of the photographing lens.

  In the external measurement phase difference detection method, a light beam received from an object is divided into two, and the two divided light beams are received by a set of focus detection sensors. Then, the subject distance is obtained from triangulation by detecting the amount of deviation of the signal output in accordance with the amount of received light, that is, the amount of relative positional deviation in the beam splitting direction. In addition, as a method using an external distance measuring sensor, there are a method for measuring propagation velocity using an ultrasonic sensor and a method for performing triangulation using an infrared sensor often used for compact cameras, but it is not particularly limited. Any method may be used.

  Next, with reference to FIG. 4, the moving speed control of the zoom lens when a zoom operation is performed during the face detection for moving image shooting will be described. Each process in FIG. 4 is executed by the CPU or the like of the camera control unit 115 by loading a program stored in a ROM, hard disk, or the like (not shown) into the RAM.

  First, in step S201, the camera control unit 115 determines whether or not the zoom lens 102 is moving.

  If the zoom lens 102 is moving, the camera control unit 115 proceeds to step S202. If the zoom lens 102 is not moving, the camera control unit 115 ends the process because there is no need to change the moving speed of the zoom lens 102. To do.

  In step S202, the camera control unit 115 determines whether or not the face area of the subject is detected in the video signal from the face detection processing circuit 112.

  If the camera control unit 115 determines that the face area has not been detected, the camera control unit 115 determines that the face area detection has failed and proceeds to step S203. On the other hand, if the camera control unit 115 determines that the face area has been detected, it can be said that the detection accuracy of the face area is guaranteed even with the current moving speed of the zoom lens 102. The process ends without changing.

  In step S <b> 203, the camera control unit 115 determines whether there is a change in the detected distance value to the subject obtained from the distance measuring sensor 117.

  If the detected distance value to the subject obtained from the distance measuring sensor 117 does not change, the camera control unit 115 proceeds to step S204. On the other hand, if there is a change in the detection distance value, the camera control unit 115 cannot capture the subject being photographed, and it is considered that the subject has changed or that there is no subject to be face-detected. The process ends without changing the moving speed of 102.

  In step S204, the camera control unit 115 controls the zoom lens driving source 110 so as to decelerate or stop the moving speed of the zoom lens 102, and ends the process.

  Note that the distance measurement sensor 117 has an error due to an individual sensor, an error due to temperature, and the like, and thus the distance measurement value varies. In the present embodiment, when the detected distance value is changed in step S203, the process is skipped so as not to change the moving speed of the zoom lens 102. If the error is within minutes, the process may proceed to step S204.

  In step S203, it is determined whether or not the detected distance value from the distance measuring sensor 117 to the subject has changed. However, by using a phase difference detection method that divides an incident light beam into two parts, receives light by a pair of line sensors, and calculates a defocus amount to the in-focus position based on a phase difference between two images on the line sensor. It may be determined whether or not there is a change in the distance to the subject. Also in this case, if there is no change in the distance to the subject corresponding to the defocus amount up to the in-focus position, the process proceeds to step S204, and if there is a change, the process ends without changing the moving speed of the zoom lens 102. To do.

  In the above-described embodiment, the face detection processing circuit 112 is used as an example of the means for detecting the characteristic part of the subject, and the detection target is a human face. For example, a human face such as an animal or a car is used. A specific object other than the above may be detected. Furthermore, the position in the imaging screen may be input from an external input means, or the position of the imaging screen may be determined by detecting the line of sight of the photographer who is looking at the viewfinder, thereby detecting the object.

  In addition, this invention is not limited to what was illustrated by said each embodiment, In the range which does not deviate from the summary of this invention, it can change suitably.

  The object of the present invention is achieved by executing the following processing. That is, a storage medium in which a program code of software that realizes the functions of the above-described embodiments is supplied to a system or apparatus, and a computer (or CPU or MPU) of the system or apparatus is stored in the storage medium. This is the process of reading the code.

  In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the program code and the storage medium storing the program code constitute the present invention.

  Moreover, the following can be used as a storage medium for supplying the program code. For example, floppy (registered trademark) disk, hard disk, magneto-optical disk, CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD + RW, magnetic tape, nonvolatile memory card, ROM or the like. Alternatively, the program code may be downloaded via a network.

  Further, the present invention includes a case where the function of the above embodiment is realized by executing the program code read by the computer. In addition, an OS (operating system) running on the computer performs part or all of the actual processing based on an instruction of the program code, and the functions of the above-described embodiments are realized by the processing. Is also included.

  Furthermore, a case where the functions of the above-described embodiment are realized by the following processing is also included in the present invention. That is, the program code read from the storage medium is written in a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer. Thereafter, based on the instruction of the program code, the CPU or the like provided in the function expansion board or function expansion unit performs part or all of the actual processing.

It is a block diagram for demonstrating the apparatus structure of the imaging device which is the 1st Embodiment of this invention. FIG. 10 is a flowchart for explaining zoom lens drive speed control when a zoom operation is performed during moving image shooting face detection. It is a block diagram for demonstrating the apparatus structure of the imaging device which is the 2nd Embodiment of this invention. FIG. 10 is a flowchart for explaining zoom lens drive speed control when a zoom operation is performed during moving image shooting face detection.

Explanation of symbols

Reference Signs List 101 first fixed lens group 102 zoom lens 103 stop 104 second fixed lens group 105 focus lens 106 image sensor 107 camera signal processing circuit 108 display device 109 recording device 110 zoom lens drive source 111 focus lens drive source 112 face detection processing circuit 113 Signal composition processing circuit 114 Face frame display signal generation circuit 115 Camera control unit 116 Zoom switch 117 Distance sensor

Claims (4)

Detection means for detecting a characteristic part of the subject;
Control means for controlling the movement of the zoom lens for changing the magnification of the subject,
The image pickup apparatus according to claim 1, wherein the control means controls the moving speed of the zoom lens to be reduced or stopped when the characteristic part of the subject is not detected by the detecting means during the movement of the zoom lens. A distance detecting means for detecting a change in the distance to the subject;
The control means decelerates or stops the moving speed of the zoom lens when there is no change in the distance to the subject, and decelerates or stops the moving speed of the zoom lens when there is a change in the distance to the subject. The imaging apparatus according to claim 1, wherein the imaging apparatus is controlled so as not to occur.   The imaging apparatus according to claim 1, wherein the characteristic part of the subject is a face region. A control step for controlling the zoom lens for changing the magnification of the subject, and a detection step for detecting a characteristic part of the subject,
In the imaging apparatus, the control step controls the driving speed of the zoom lens to be decelerated or stopped when the characteristic portion of the subject is not detected in the detection step during the movement of the zoom lens. Control method.

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