I`D “HE @52
Contents
1. Upon determina tion of the autofocus area the CPU 38 transmits AF frame information indicating contour information of the autofocus area to the lens CPU of the lens device 12 through the SCI 58 0073 The automatic tracking mode is a mode for perform ing processing to set a predetermined object within the auto focus area detect a presence area of the target to be tracked in an image newly captured by the imaging unit and determine the presence area as a new autofocus area The automatic tracking mode has a plurality of modes including an object tracking mode a face detection tracking mode a face recognition tracking mode and a fully automatic tracking mode After the automatic tracking mode is selected on the screen 66a of the LCD 66 a desired mode is further selected Nov 14 2013 by auser from the object tracking mode the face detection tracking mode the face recognition tracking mode andthe fully automatic tracking mode Incidentally configuration may be made so that a desired mode can be selected by a user from the object tracking mode the face detection tracking mode the face recognition tracking mode and the fully automatic tracking mode in the menu screen of the screen 66a of the LCD 66 0074 The object tracking mode is a mode for tracking an arbitrary object At least part of the object set as the target to be tracked is displayed to be enclosed in2. an endoscope imag ing apparatus or the like 0125 The present application is based on Japanese Patent Application No 2011 8333 filed on Jan 18 2011 the con tents of which are incorporated herein by reference EXPLANATIONS OF REFERENCE SIGNS 0126 1 video camera system 0127 10 television camera 0128 12 lens device 0129 14 camera body 0130 16 view finder 0131 18 image processing unit 0132 20 AF frame operation portion 0133 30 main board 0134 40 AF unit 0135 32 pattern matching process computing board 0136 34 face recognition process computing board 0137 38 50 52 CPU 0138 66 liquid crystal display LCD 1 An autofocus system comprising an imaging unit which captures an image of an object formed by an optical system an autofocus portion which performs focus adjustment of the optical system on an autofocus area set in the image captured by the imaging unit so that the object within the autofocus area comes into focus an AF area tracking processing portion which performs tracking processing to set a predetermined object within the autofocus area as a target to be tracked detect a presence area of the target to be tracked in an image newly captured by the imaging unit and determine the presence area as a new autofocus area US 2013 0300917 Al a depth of field computing portion which calculates a depth of field based on information acquired from the optical system and a control po
3. depth of field is calculated as in the following expression 1 In the expression 1 Lr is the rear depth of field and Lf is the front depth of field Depth of Field Lr Lf 0088 The rear depth of field Lr is calculated as in expres sion 2 The front depth of field Lf is calculated as in expres sion 3 In the following expressions the focal distance of the lens of the lens device 12 is f the diaphragm value f number is FNo the permissible circle of confusion is and the object distance is L expression 1 FNo L expression 2 Rear Depth of Field Lr FE 5 FNo L FNo L expression 3 Front Depth of Field Lf FE 8 FNo L 0089 When a blurring amount of an image is not higher than a certain value in the condition that the image of an object on the optical axis of the lens is formed on the imaging surface the imaging surface of the image sensing device it appears as if the lens focuses in a range around the point where the object is brought into focus A circle having the certain value of the blurring amount of the image on this occasion assumed to be the diameter and the optical axis assumed to be the center is a permissible circle of confusion Incidentally the diameter of the permissible circle of confusion changes in US 2013 0300917 Al accordance with the image size of the image sensing device the performance of the camera usage conditions etc 0090 In the range where it appears as if the
4. a face image which is to be set as the target to be tracked is determined in accordance with the size and position of the face On the other hand when the face image of the person is not included in the captured image automatic tracking based on the aforemen tioned object tracking mode is executed 0078 The video camera system 1 configured as described above executes automatic tracking when the automatic track ing mode is selected When automatic tracking is performed a depth of field is calculated based on information obtained from the lens device 12 and control is made to execute or stop automatic tracking based on the depth of field In this manner mistracking can be avoided even when the angle of view for capturing an image is changed to the wide angle side by zooming of the lens device 12 at the time of execution of automatic tracking 0079 FIG 4 shows an example of a screen displayed on the LCD when automatic tracking is stopped When an object as a target to be tracked becomes small in the case where zooming is set at a wide angle as shown in FIG 4 contrast with a sufficient level cannot be obtained in the set autofocus area even if the autofocus area is set in accordance with the object In such a case the depth of field is so deep that execution of automatic tracking is automatically stopped based on the depth of field The autofocus area is changed to apredetermined position for example the center of the imag ing area s
5. a screen displayed on the touch panel including liquid crystal display in the autofocus system according to the embodiment of the invention 0064 As shown in FIG 3 a menu screen menu image including various buttons 300 and 302 and an AF frame 204 indicating an autofocus area 200 see FIG 2 set currently are displayed on a screen 66a ofthe LCD 66 while superimposed on a video image captured by the television camera 10 Images superimposed on the captured video image like the various buttons 300 and 302 of the menu screen and the AF frame 204 are generated by the CPU 38 ofthe main board 30 in the image processing unit 18 shown in FIG 1 Those images are displayed on the LCD 66 while superimposed on the video image which is captured by the television camera 10 and which is outputted from the decoder 36 in the super imposer 42 Incidentally control concerned with display dis play contents of the LCD 66 is performed by the CPU 38 0065 In addition an indicator 304 visually indicating an angle of view of the lens based on information acquired from the lens device 12 is provided in the screen 66a of the LCD 0066 On the other hand the LCD 66 is provided with a touch panel When a touch operation is performed so that the screen 66a of the LCD 66 is touched with a finger etc position information indicating the touched position coordi nates is given to the CPU 38 In this manner the position and Operation kind tap double tap et
6. be tracked 16 The autofocus system as claimed in claim 8 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked Kk ke
7. computing board 34 0057 Incidentally the image processing unit 18 is pro vided with a memory etc which is readable and writable by the CPU 38 and which can be used suitably for storage of processing data etc In addition information about the posi tion size and shape of the autofocus area set in the AF frame setting processing in the automatic tracking mode which will be described later is stored in this memory It is preferable that the setting information about the position size and shape of the autofocus area can be changed by a predetermined opera tion of the AF frame operation portion 20 in accordance with user s cameraman s preference 0058 The super imposer 42 is a circuit which combines a video signal of captured video images obtained from the Nov 14 2013 decoder 36 with an image signal generated by the CPU 38 and outputs displays the combined video signal to on the LCD 66 In this manner the video images captured by the televi sion camera 10 can be displayed on the LCD 66 in the same manner as on the viewfinder 16 mounted in the camera body 14 At the same time an image of the currently set autofocus area a menu screen menu image etc on which an input operation is allowed to be performed through the touch panel etc can be displayed on the LCD 66 while superimposed on the captured video images Incidentally it is a matter of course that only the image generated by the CPU 38 can be displayed while not sup
8. lens device 12 through the SCI 58 step S24 When the processing of the step S24 is completed the procedure returns to the processing of the step S10 0094 When the determination in the step S20 results in YES the CPU 38 determines whether Face_flag is false or not step S26 When Face_flag is false the processing procedure goes to step S30 When Face flag is true the processing procedure goes to step S28 0095 When the determination in step S26 results in YES the CPU 38 determines whether the face image is detected within the captured image or not by the face detection pro cessing in the step S14 step S30 When the face image is detected within the captured image the processing procedure goes to step S32 When the face image is not detected within the captured image the processing procedure goes to step S36 0096 When the determination in the step S30 results in YES the CPU 38 sets Face_flag at true step S31 Succes sively to the processing of the step S31 the CPU 38 starts automatic tracking step S32 The CPU 38 sets updates the range of the detected face image as a new autofocus area and transmits AF frame information indicating information about the autofocus area to the lens CPU of the lens device 12 step S34 The les device 12 executes autofocus adjustment in the new autofocus area based on the AF frame information step S36 When the processing of the step S36 is completed the proced
9. lens focuses the image forming range of the image forming surface side is referred to as the depth of focus Incidentally the depth d of focus can be calculated based on d 28xFNo 0091 Incidentally the depth of field has the following properties 1 The depth of field is deeper as the diaphragm value is larger 11 The depth of field is deeper as the focal distance is shorter 111 The depth of field is deeper as the object distance is longer iv The rear depth of field is deeper than the front depth of field 0092 Successively to the step S16 the CPU 38 of the main board 30 compares the depth of field calculated in the step S16 with a predetermined threshold to thereby determine whether the depth of field is shallower than the threshold or not step S20 Here assume that the threshold is 50 as long as the object distance When the depth of field is shallower than the threshold the processing procedure goes to step S26 When the depth of field is not shallower than the threshold the processing procedure goes to step S22 0093 When the determination in the step S20 results in NO the CPU 38 determines that automatic tracking should be stopped and sets automatic tracking at OFF step S22 The CPU 38 determines that the autofocus area is moved to a set default position for example the center of the captured image and transmits AF frame information indicating infor mation about the autofocus area to the lens CPU of the
10. song program sports broadcasting or the like in which each person to be imaged is determined preliminarily In this mode authentication data of the face of the person set as the target to be tracked is imported from the face authentication US 2013 0300917 Al data card 74 loaded in the slot not shown shown in FIG 1 Face detection processing is performed in the CPU 52 of the face recognition process computing board 34 is performed in the same manner as in the face detection tracking mode and the face image of the target to be tracked is detected from detected face images by a well known face authentication process using the authentication data The CPU 38 of the main board 30 determines the range of the face image detected by the face recognition process as a new autofocus area and transmits information about the autofocus area to the lens CPU of the lens device 12 0077 In the fully automatic tracking mode well known face detection processing for detecting a face image of an arbitrary person from captured images is performed in the CPU 52 of the face recognition process computing board 34 in the same manner as in the aforementioned face detection tracking mode When the face image of the person is included in the detected face image the face image does not have to be designated by an operator but can be automatically set as the target to be tracked When a plurality of face images are included in the captured image on that occasion
11. sufficient contrast cannot be obtained from the image of the object in the range of the AF area Therefore the accuracy of automatic tracking is low ered In such a case automatic tracking is controlled to be OFF and autofocus adjustment is controlled to be ON 0113 In the case where the lens does not focus in any position of the captured image and the object as the target to be tracked is too small both automatic tracking and autofocus adjustment are controlled to be OFF 0114 In this specification the autofocus system is dis closed as follows 1 An autofocus system including 0115 an imaging unit which captures an image of an object formed by an optical system 0116 an autofocus portion which performs focus adjust ment of the optical system on an autofocus area set in the image captured by the imaging unit so that the object within the autofocus area comes into focus 0117 an AF area tracking processing portion which per forms tracking processing to set a predetermined object within the autofocus area as a target to be tracked detect a presence area of the target to be tracked in an image newly captured by the imaging unit and determine the presence area as a new autofocus area 0118 adepth of field computing portion which calculates a depth of field based on information acquired from the opti cal system and 0119 a control portion which controls execution of the focus adjustment by the autofocus portion and the
12. the AF frame The object tracking mode is a mode useful for capturing each image in horse racing broadcasting car racing broadcasting or the like for tracking an object other than a person s face When an operator designates the autofocus area so that an image of an arbitrary object the operator wants to set as the target to be tracked is included in each of captured video images in this mode the object within the autofocus area enclosed by the AF frame is set as the target to be tracked The image of the target to be tracked is registered as a reference pattern and a pattern matching process for detecting an image range coincident with the reference pattern is performed on the sequentially obtained captured images in the CPU 50 of the pattern matching process computing board 32 The CPU 38 of the main board 30 determines the range where the reference pattern is detected as a new autofocus area and transmits information about the autofocus area to the lens CPU of the lens device 12 Incidentally when focus control based on AF is not performed in the lens device 12 while object automatic tracking starts when it is not in the AF mode an instruction to start AF is also issued in conjunction with the start of the object automatic tracking 0075 The face detection tracking mode is a mode for tracking a face of an arbitrary person with the AF frame A face area of the person set as the target to be tracked is displayed as the autofocus area t
13. 14 so that each image captured by the television camera 10 is displayed on the viewfinder 16 Various kinds of infor mation other than the captured image is further displayed on the viewfinder 16 For example an image frame image indicating an AF frame which is the contour of the currently set autofocus area is displayed while superimposed on the captured image 0030 The lens device 12 has an imaging lens zoom lens attached to the lens mount of the camera body 14 so that an image of an object 28 is formed on an imaging surface of an image sensing device of the camera body 14 by the imaging lens Though not shown movable portions for adjusting imaging conditions such as a focus lens group a zoom lens group a diaphragm etc are provided as constituent elements of the imaging lens These movable portions are electrically driven by a motor servo mechanism For example the focus lens group and the zoom lens group move in an optical axis direction so that the focus object distance is adjusted by the movement of the focus lens group while the focal distance zoom ratio is adjusted by the movement of the zoom lens group 0031 Incidentally as long as at least the focus lens group can be electrically driven the other movable portions may be driven only manually in the system concerned with autofocus adjustment 0032 An AF unit 40 and a lens CPU not shown etc are further mounted in the lens device 12 The lens CPU generally contr
14. F processing portion 0037 Whenever the video signal for one scene is acquired thus from the AF imaging circuit whenever a focus evalua tion value is obtained by the AF processing portion the focus evaluation value is acquired from the AF processing portion and the focus lens group is controlled to maximize locally maximize the acquired focus evaluation value that is to maximize the contrast of the object image within the autofo cus area For example a mountain climbing method is gen erally known as the focus lens group controlling method based on the focus evaluation value The focus lens group is moved in a direction of increasing the focus evaluation value When a point at which the focus evaluation value begins to decrease is detected the focus lens group is set at that posi tion In this manner the object within the autofocus area is brought into focus automatically 0038 Although the aforementioned AF processing por tion acquires a video signal from the AF image sensing device mounted in the lens device 12 in order to calculate the focus evaluation value configuration may be made so that the aforementioned AF processing portion acquires a video sig nal of each image captured by the image sensing device of the camera body 14 from the camera body 14 In addition any AF unit may be used as long as the AF unit can automatically focus on an object within the autofocus area US 2013 0300917 Al 0039 Next the autofocus ar
15. HE CENTER 22 STOP TRACKING 528 gt YES UPDATE THE FRAME POSITION 36 EXECUTE AF Patent Application Publication Nov 14 2013 Sheet 5 of 5 US 2013 0300917 Al FIG 6 START S40 READ THE DIAPHRAGM OBJECT DISTANCE AND FOCAL DISTANCE S42 CALCULATE THE DEPTH OF FIELD IS THE DEPTH OF FIELD INFINITE 548 US 2013 0300917 Al AUTOFOCUS SYSTEM CROSS REFERENCE TO RELATED APPLICATION 0001 This is a continuation of International Application No PCT JP2012 050979 filed on Jan 18 2012 and claims priority from Japanese Patent Application No 2011 008333 filed on Jan 18 2011 the entire disclosures of which are incorporated herein by reference TECHNICAL FIELD 0002 The present invention relates to an autofocus system provided with an automatic tracking function of defining an object within an autofocus AF area as an object to be tracked and updating the AF area according to the position of the object to be tracked BACKGROUND ART 0003 There is known a television camera system for broadcasting use or business use provided with an autofocus function of automatically focusing on an object within a specific imaging area This type camera system generally uses contrast method AF which is performed by detecting the height of contrast of a captured image and controlling the focus of a capturing optical system to maximize locally maximize the contras
16. US 20130300917A1 a2 Patent Application Publication 10 Pub No US 2013 0300917 A1 as United States YATA 43 Pub Date Nov 14 2013 54 AUTOFOCUS SYSTEM 71 Applicant FUJIFILM Corporation Tokyo JP 72 Inventor Kunio YATA Saitama shi JP 21 Appl No 13 945 205 22 Filed Jul 18 2013 Related U S Application Data 63 Continuation of application No PCT JP2012 050979 filed on Jan 18 2012 30 Foreign Application Priority Data Jan 18 2011 TP settee 2011 008333 Publication Classification 51 Int Cl HOAN 5 232 2006 01 CAMERA u 14a 20 OPERATION PORTIO A ng OUTPUT TOUCH PANEL INCLUDING LCD TOUCH PANEL POSITION SIGNAL 52 U S Cl CPG sand HOAN 5 23212 2013 01 A net 348 349 57 ABSTRACT An autofocus system includes an imaging unit which cap tures an image of an object formed by an optical system an autofocus portion which performs focus adjustment of the optical system on an autofocus area set in the image captured by the imaging unit so that the object within the autofocus area comes into focus an AF area tracking processing portion which performs tracking processing to set a predetermined object within the autofocus area as a target to be tracked detect a presence area of the target to be tracked in an image newly captured by the imaging unit and determine the pres ence area as a new autofocus area a depth of field
17. bject distance and a focal distance from the lens device 12 0055 The CPU 38 of the main board 30 performs arith metic processing for calculating a depth of field using the diaphragm value the object distance and the focal distance acquired from the lens device 12 and control processing for performing control to execute or stop automatic tracking based on the calculated depth of field The arithmetic process ing and the control processing may be performed by any one of the main board 30 the pattern matching process computing board 32 and the face recognition process computing board 34 or by a separately provided processing operation board not shown 0056 The decoder 36 is a circuit for converting a video signal SDTV signal of video images of the television cam era 10 inputted to the image processing unit 18 from the down converter 46 into data to which digital processing can be applied in the image processing unit 18 The decoder 36 performs A D conversion processing etc for converting an analog SDTV signal into a video signal of digital data The video signal of video images outputted from the decoder 36 is also sent to the pattern matching process computing board 32 and the face recognition process computing board 34 so that the video images captured by the television camera 10 can be acquired as captured images each corresponding to one frame also in the pattern matching process computing board 32 and the face recognition process
18. c of the touch operation US 2013 0300917 Al performed on the screen 66a of the LCD 66 are detected by the CPU 38 Processing in accordance with this operation is executed by the CPU 38 0067 As basic operations in the screen 66a of the LCD 66 there are an operation for inputting an instruction assigned in advance to each of the buttons 300 and 302 and an operation for designating the autofocus area area enclosed by the AF frame 204 The former operation is performed by tapping the position of the button 300 or 302 with a finger etc The latter operation for designating the autofocus area is performed for example in such a manner that when a position to which the autofocus area is intended to be moved is tapped on the screen 66a of the LCD 66 on which each captured video image is displayed the autofocus area can be moved so that the posi tion comes to the center In addition an apex or a side of the AF frame 204 indicating the contour of the autofocus area can be moved to a position to where the touched apex or side is dragged by a dragging operation for touching the apex or side with a finger etc and sliding the apex or side so that the position size and shape of the autofocus area can be changed 0068 Incidentally the position size and shape of the auto focus area can be changed by operations of the position opera tion member 60 the size operation member 62 and the shape operation member 64 in the AF frame operation portio
19. changed by zooming 0009 In the camera in Patent Literature 1 mistracking is apt to occur when the angle of view is changed by zooming Nov 14 2013 because the automatic tracking function cannot be automati cally switched on off in accordance with the change in the angle of view by zooming 0010 The invention provides an autofocus system pro vided with an automatic tracking function in which occur rence of mistracking can be suppressed when the angle of view is changed by zooming Means for Solving the Problem 0011 An autofocus system according to the invention includes 0012 an imaging unit which captures an image of an object formed by an optical system 0013 an autofocus portion which performs focus adjust ment of the optical system on an autofocus area set in the image captured by the imaging unit so that the object within the autofocus area comes into focus 0014 an AF area tracking processing portion which per forms tracking processing to set a predetermined object within the autofocus area as a target to be tracked detect a presence area of the target to be tracked in an image newly captured by the imaging unit and determine the presence area as a new autofocus area 0015 adepth of field computing portion which calculates a depth of field based on information acquired from the opti cal system and 0016 a control portion which controls execution of the focus adjustment by the autofocus portion and th
20. computing portion which calculates a depth of field based on information acquired from the optical system and a control portion as defined herein US 2013 0300917 A1 Nov 14 2013 Sheet 1 of 5 Patent Application Publication KA mm en mm en en me nn tn een ee gt a mn A A m m mn mn mm nn an Vine nn nn o MANY A H 9 NOLLISOd IWY TYNDIS NOLLISOd TANVd HONOL 091 SNIGNTONI TANVd HONOL anano br ee mn r ate maner m OILHOd Nolvetddo En OG vs nao Je ep 19S VAJAV Patent Application Publication Nov 14 2013 Sheet 2 of 5 US 2013 0300917 Al FIG 2 202 AF AREA IMAGING AREA FIG 3 66a AF FRAME FIXED 300 AUTOMATIC TRACKING 302 Patent Application Publication Nov 14 2013 Sheet 3 of 5 US 2013 0300917 Al FIG 4 66a 306 TRACKING OFF Patent Application Publication FIG 5 Nov 14 2013 Sheet 4 of 5 US 2013 0300917 A1 10 Face_flag false CAPTURE IMAGE RECEIVE THE DIAPHRAGM VALUE OBJECT DISTANCE AND FOCAL DISTANCE FROM LENS CALCULATE THE DEPTH OF FIELD 20 12 14 16 DEPTH NO OF FIELD lt 50 OF OBJECT DISTANCE YES 26 Face_flag false ne YES 30 IS THERE ANY PERSON DETECTED WITHIN THE FRAME Face_flag true START TRACKING MOVE THE FRAME POSITION TO T
21. e tracking processing by the AF area tracking processing portion based on the depth of field calculated by the depth of field comput ing portion Advantageous Effects of Invention 0017 According to the invention it is possible to provide an autofocus system provided with an automatic tracking function in which occurrence of mistracking can be sup pressed when the angle of view is changed by zooming BRIEF DESCRIPTION OF DRAWINGS 0018 FIG 1 A block diagram showing an overall configu ration of a video camera system for explaining an autofocus system according to an embodiment of the invention 0019 FIG 2 A view for explaining an example of an autofocus area in the autofocus system according to the embodiment of the invention 0020 FIG 3 A view showing an example of a screen displayed on a touch panel including liquid crystal display in the video camera system in FIG 1 0021 FIG 4 A view showing an example of the screen displayed on the LCD when automatic tracking is stopped 0022 FIG 5 A flowchart showing a processing procedure in an automatic tracking mode in the autofocus system according to the embodiment of the invention 0023 FIG 6A flow chart showing a processing procedure of autofocus adjustment control in the autofocus system according to the embodiment of the invention EMBODIMENTS FOR CARRYING OUT THE INVENTION 0024 An embodiment of an autofocus system with an automatic tracking function accordi
22. ea in the autofocus system according to the embodiment of the invention will be described FIG 2 is a view showing an example of the auto focus area in the autofocus system according to the embodi ment of the invention As shown in FIG 2 an autofocus area 200 is set as a quadrilateral area with respect to an imaging area 202 or an imaging range of the image sensing device in the camera body 14 The contour of the autofocus area 200 is indicated as an AF frame 204 In the autofocus system accord ing to the embodiment of the invention an object to be imaged within the autofocus area 200 area within the AF frame 204 of the image sensing device is brought into focus 0040 Incidentally this specification is placed on the assumption that the autofocus area 200 relative to the imaging area 202 is determined based on three factors i e the position size and shape aspect ratio of the contour AF frame 204 of the autofocus area 200 and the autofocus area 200 is changed when at least one of the three factors i e the position size and shape of the AF frame 204 is changed 0041 In addition the lens device 12 is connected to the camera body 14 through a cable or directly so that various information can be exchanged between the lens device 12 and the camera body 14 through serial communication interfaces 12a and 14a provided respectively in the lens device 12 and the camera body 14 In this manner information of the AF frame set currently
23. entally the imaging ranges of the two image sensing devices do not need to be perfectly coin cident with each other For example the imaging range ofthe AF image sensing device may be a larger range including the imaging range of the image sensing device of the camera body 14 0035 The AF processing portion acquires a video signal from the AF imaging circuit and calculates a focus evaluation value indicating the level of contrast ofan object image within the autofocus area based on the video signal For example aftera high frequency component signal is extracted by a high pass filter from the video signal obtained from the AF image sensing device a signal of an image of the autofocus area set as will be described later among the high frequency compo nent signal is integrated scene by scene frame by frame The integrated value obtained thus scene by scene indicates the level of contrast of the image of the autofocus area The integrated value is given as a focus evaluation value to the lens CPU 0036 The lens CPU acquires information of an AF frame AF frame information indicating contour information posi tion size shape etc of the autofocus area from the image processing unit 18 as will be described later and designates the autofocus area designated by the AF frame information as a target range for AF processing The focus evaluation value obtained based on the image video signal of the autofocus area is acquired from the A
24. erimposed on the captured video images 0059 The RAM 39 is a memory which temporarily stores data used in arithmetic processing of the CPU 38 0060 The pattern matching process computing board 32 and the face recognition process computing board 34 are computing boards for individually performing pattern match ing and face detection authentication process The pattern matching process computing board 32 and the face recogni tion process computing board 34 are provided with the CPUs 50 and 52 which perform arithmetic processing VRAMs 54 and 56 which temporarily store image data respectively etc 0061 In addition a slot not shown into which a face authentication data card 74 is loaded as an external memory such as an SD Secure Digital card a USB memory etc is provided in the image processing unit 18 When the face ofa specific person is detected by face recognition recognition data indicating the face of the specific person are stored in advance in the face authentication data card 74 When the face authentication data card 74 is loaded into the slot the CPU 38 can read authentication data required for face recognition from the face authentication data card 74 0062 Successively control of the autofocus area per formed by the image processing unit 18 configured as described above will be described in conjunction with pro cessing concerned with display and operation of the LCD 66 0063 FIG 3 is a view showing an example of
25. guration can be made in such a manner that US 2013 0300917 Al part or all of the operation members 60 62 64 68 and 70 or the LCD 66 are provided suitably so that the position of the AF frame can be changed manually 0051 The configuration and processing contents of the image processing unit 18 will be described below 0052 The image processing unit 18 includes a main board 30 a pattern matching process computing board 32 and a face recognition process computing board 34 CPUs 38 50 and 52 are mounted in the main board 30 the pattern match ing process computing board 32 and the face recognition process computing board 34 respectively Arithmetic pro cessing is performed individually in each board The CPUs 38 50 and 52 are connected by a bus or a control line so that exchange of data synchronization of arithmetic processing etc among the CPUs 38 50 and 52 can be attained 0053 Processing in the image processing unit 18 is gen erally controlled in the main board 30 In addition to the CPU 38 for performing arithmetic processing the SCI 58 a decoder A D converter 36 a super imposer 42 a RAM 39 etc are mounted in the main board 30 0054 The SCI 58 is an interface circuit for performing serial communication with the SCI 12a of the les device 12 as described above The SCI 58 transmits the AF frame infor mation etc to the lens device 12 In addition the SCI 58 receives information including a diaphragm value an o
26. h will be described later is configured to be detachable from the image processing unit 18 Incidentally the AF frame operation por tion 20 may be provided in such a form that the AF frame Operation portion 20 is partially or entirely formed as a sepa rate device from the image processing unit 18 and connected to the image processing unit 18 by a cable etc 0047 The AF frame operation portion 20 is an operation portion for mainly performing operation concerned with con trol of the AF frame The AF frame operation portion 20 is provided with an operation member by which an operator can input an instruction of the autofocus area 200 by manual Operation and an operation member by which operation con cerned with automatic tracking for automatically tracking a desired object can be performed 0048 Although the details will be omitted the AF frame operation portion 20 includes a position operation member 60 for example ajoystick or a trackball for moving the position of the autofocus area the position of the AF frame up down left and right by user s manual operation a size operation member 62 for example a knob for changing the size of the autofocus area the size of the AF frame by manual opera tion a shape operation member 64 for example a knob for changing the shape of the autofocus area the shape of the AF frame by manual operation a tracking start switch 68 for issuing an instruction to start automatic tracking and a t
27. in the AF unit 40 is also transmitted to the camera body 14 and an image ofthe AF frame corresponding to the position size and shape of the AF frame set currently in each video image displayed on the viewfinder 16 by process ing in the camera body 14 is displayed while superimposed on the video image 0042 Theimage processing unit 18 is a processing portion for designating the autofocus area the position size and shape aspect ratio of the AF frame set in the AF unit 40 of the lens device 12 by manual operation or automatic tracking processing which will be described later For example the image processing unit 18 is received in a not shown housing and placed in a side portion of a barrel of the imaging lens of the lens device 12 an outer wall surface of the housing of the camera body 14 etc Incidentally the position where the image processing unit 18 is placed in the lens device 12 or the camera body 14 is not limited thereto but may be any other arbitrary position In addition the image processing portion 18 may be disposed in a portion other than the lens device 12 or the camera body 14 0043 The image processing unit 18 has an SCI 58 The SCI 58 is connected to the lens device 12 so the SCI 58 can exchange various signals with the lens CPU through the SCI 12a In this manner AF frame information for designating the autofocus area 200 is given to the lens CPU of the lens device 12 from the image processing unit 18 so that the aut
28. mination in the step S44 is made that the depth of field is infinite the processing procedure goes to step S46 When the determination is made that the depth of field is not infinite the processing procedure goes to step S48 0106 When the determination in the step S44 results in YES the CPU 38 sets autofocus adjustment at OFF step S22 The CPU 38 transmits information indicating stop of autofocus adjustment to the AF unit 40 through the SCI 58 step S46 When the processing ofthe step S46 is completed the procedure returns to the processing of the step S40 0107 When the determination in the step S44 results in NO the CPU 38 allows execution of autofocus adjustment step S48 The AF unit 40 executes autofocus adjustment in the already set autofocus area step S48 When the process ing of the step S48 is completed the procedure returns to the processing of the step S40 0108 According to the aforementioned video camera sys tem 1 when autofocus adjustment is performed an object within a set autofocus area is brought into focus When the US 2013 0300917 Al angle of view is changed by zooming on that occasion deter mination is made as to whether execution of autofocus adjust ment is allowed or not based on the depth of field When determination is made that execution of autofocus adjustment is not allowed autofocus adjustment is automatically stopped In addition when determination is made that execu tion of autofocus adj
29. n 20 0069 To describe the menu screen menu image dis played on the screen 66a of the LCD 66 a fixation mode selection button 300 indicated as AF frame fixed and an automatic tracking mode selection button 302 indicated as automatic tracking are buttons for selecting an autofocus control mode in FIG 3 When one of these buttons 300 and 302 is tapped a desired mode can be selected from the fixa tion mode and the automatic tracking mode 0070 The fixation mode is a mode manual mode in which an operator designates an autofocus area the position size and shape by a manual operation and an AF frame is displayed in the designated position so that the autofocus area is fixed This fixation mode is a mode useful for capturing images in a news program for which the camera is hardly moved 0071 When the fixation mode selection button 300 is tapped on the screen 66a of the LCD 66 in FIG 3 the fixation mode is selected so that the CPU 38 mounted in the main board 30 of the image processing unit 18 executes processing of the fixation mode 0072 That is the CPU 38 determines the autofocus area based on an operation on the screen 66a of the LCD 66 for changing the autofocus area or an operation on an operation member the position operation member 60 the size opera tion member 62 or the shape operation member 64 for chang ing the AF frame 204 provided in the AF frame operation 20 by a manual operation as described above
30. nd focal distance obtained from the optical system Nov 14 2013 8 The autofocus system as claimed in claim 4 wherein the depth of field computing portion calculates the depth of field based on information about diaphragm value object distance and focal distance obtained from the optical system 9 The autofocus system as claimed in claim 1 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 10 The autofocus system as claimed in claim 2 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 11 The autofocus system as claimed in claim 3 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 12 The autofocus system as claimed in claim 4 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 13 The autofocus system as claimed in claim 5 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 14 The autofocus system as claimed in claim 6 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked 15 The autofocus system as claimed in claim 7 wherein the AF area tracking processing portion sets a human image within the autofocus area as a target to
31. ng the autofocus area in an imaging range imaging area is set based on information about the position size and shape of the initially set autofocus area stored in the memory not shown of the main board 30 AF frame information indicating the information the position size and shape of the thus set autofocus area is transmitted to the lens CPU of the lens device 12 through the SCI 58 In this manner the autofocus area is set in a range designated by the AF frame information in the AF unit 40 of the lens device 12 0084 Successively the CPU 52 of the face recognition process computing board 34 imports image data ofa captured image corresponding to one frame from the decoder 36 step S12 The CPU 38 of the main board 30 is notified of the imported image data 0085 Next the CPU 38 of the main board 30 acquires the diaphragm value the object distance and the focal distance from the lens device 12 step S14 In the step S14 the CPU 38 edits the acquired diaphragm value object distance and focal distance as data linked to a corresponding face image and temporarily stores the edited diaphragm value object distance and focal distance in the RAM 39 0086 Next the CPU 38 of the main board 30 executes arithmetic processing to calculate the depth of field using the data including the diaphragm value the object distance and the focal distance generated in the step S14 step S16 0087 In the arithmetic processing in the step S16 the
32. ng to the invention will be described below with reference to the drawings US 2013 0300917 Al 0025 FIG 1 is a block diagram showing an overall con figuration of a video camera system for explaining the auto focus system according to the embodiment of the invention For example this video camera system is used for capturing an image with a television camera for broadcasting use or business use 0026 As shown in FIG 1 the video camera system 1 includes a television camera 10 an image processing unit 18 constituting an AF area tracking processing portion perform ing automatic tracking and an AF frame operation portion 20 0027 The television camera 10 includes a camera body 14 made of an HD camera corresponding to a high definition television HD TV system and a lens device 12 having an imaging lens optical system attached to a lens mount of the camera body 14 0028 An image sensing device for example a CCD image sensing device a required signal processing circuit etc are mounted in the camera body 14 An image formed by the imaging lens of the lens device 12 is photoelectrically converted by the image sensing device and then subjected to required signal processing by the signal processing circuit so that the image is outputted as an HDTV system video signal HDTV signal to the outside from a video signal output terminal etc of the camera body 14 0029 A viewfinder 16 is further mounted in the camera body
33. o be enclosed with the AF frame The face detection tracking mode is a mode useful for capturing images in a song program or the like for detecting and tracking a person s face In this mode first well known face detection processing for detecting a face image of an arbitrary person from each captured image is performed in the CPU 52 of the face recognition process computing board 34 When an operator designates a face image which is to be set as the target to be tracked from the detected face image the designated face image is set as the target to be tracked Then face detection processing is performed on sequentially obtained captured images by the CPU 52 of the face recog nition process computing board 34 and processing for iden tifying the face image of the target to be tracked from the detected face images is performed by the CPU 38 of the main board 30 The CPU 38 of the main board 30 determines the range of the detected face image of the target to be tracked as a new autofocus area and transmits information about the autofocus area to the lens CPU of the lens device 12 0076 The face recognition tracking mode is a mode for tracking a person s face registered preliminarily as authenti cation data with the AF frame The face image of the person registered as the target to be tracked is displayed as the auto focus area to be enclosed with the AF frame The face recog nition tracking mode is a mode useful for capturing images in a
34. o that the AF frame 204 representing the contour of the changed autofocus area is displayed while superimposed on the screen 66a In addition a tracking stop mark 306 visually indicating the stop of automatic tracking is displayed on the screen 66a When automatic tracking is stopped it is arbitrary that either autofocus is performed or the lens is fixed to a previous focus position As will be described later execu tion or stop of autofocus adjustment may be controlled based on the depth of field 0080 When automatic tracking is stopped autofocus adjustment is performed on an object in the predetermined position of the imaging area for example the center of the imaging area 0081 Successively processing when the automatic track ing mode performed by the image processing unit 18 is selected will be described Incidentally processing ofthe face recognition tracking mode will be described as follows by way of example Nov 14 2013 0082 FIG 5 is a flow chart showing a processing proce dure when the automatic tracking mode in the CPU of the image processing unit is selected 0083 When the automatic tracking mode is selected by a predetermined operation first the CPU 38 of the main board 30 performs AF frame setting processing to set an autofocus area at a predetermined initial position A flag Face_flag indicating whether face recognition is performed or not is set to be false step S10 In the AF frame setting processi
35. ofocus area 200 in the AF unit 40 is set based on the AF frame information 0044 In addition a video input connector for importing a video signal is provided in the image processing unit 18 A video output connector of the camera body 14 is connected to the video input connector through a down converter 46 In this manner an HDTV signal outputted from the video output connector of the camera body 14 is converted down con verted into a standard television NTSC National Television System Committee type video signal SDTV signal and inputted to the image processing unit 18 0045 Although details will be given later the image pro cessing unit 18 performs processing for fetching each cap Nov 14 2013 tured image corresponding to one frame sequentially fromthe video signal inputted from the camera body 14 and detecting an object as a predetermined target to be tracked from the captured image when automatic tracking processing is executed The image processing unit 18 determines the auto focus area 200 so as to bring the object into focus by AF and then transmits information of the determined autofocus area 200 to the lens CPU of the lens device 12 Incidentally the configuration and processing contents of the image process ing unit 18 will be described later 0046 The AF frame operation portion 20 is provided as a device integrated with the image processing unit 18 A touch panel including liquid crystal display LCD 66 whic
36. ols the lens device 12 as a whole The AF unit 40 is a processing portion for acquiring information necessary for focus control automatic focus adjustment based on the auto focus adjustment Though not shown an AF processing por tion an AF imaging circuit etc constitute the AF unit 40 0033 TheAF imaging circuit is disposed in the lens device 12 in order to acquire a video signal for AF processing The AF imaging circuit has an image sensing device referred to as AF image sensing device such as a CCD image sensing device and a processing circuit which outputs an output signal of the AF image sensing device as a video signal with Nov 14 2013 apredetermined format Incidentally the video signal output ted from the AF imaging circuit is a luminance signal 0034 Object light incident on the image sensing device of the camera body 14 is branched by a half mirror or the like disposed on an optical path of the imaging lens so that an image of the branched object light is formed on the imaging surface of the AF image sensing device The imaging area and the object distance the distance to the object coming into focus in the AF image sensing device are formed to be coincident with the imaging area and the object distance inthe image sensing device of the camera body 14 so that the object image taken in by the AF image sensing device is coincident with the object image taken in by the image sensing device of the camera body 14 Incid
37. rack ing stop switch 70 for issuing an instruction to stop automatic tracking The setting statuses of the operation members 60 62 64 68 and 70 are read by a CPU 38 of a main board 30 in the imaging processing unit 18 0049 In addition the touch panel including liquid crystal display hereinafter referred to as LCD is provided in the AF frame operation portion 20 The LCD 66 is configured so that setting of a mode concerned with automatic tracking etc can be inputted by touch operation tap on the LCD 66 An image displayed on the LCD 66 can be switched suitably in accordance with the setting contents by the CPU 38 of the image processing unit 18 0050 Incidentally in the case where only automatic track ing based on an automatic tracking mode which will be described later is performed in this embodiment part or all of the operation members 60 62 64 68 and 70 of the AF frame Operation portion 20 can be dispensed with In addition the LCD 66 can be also dispensed with According to the auto matic tracking mode which will be described later automatic tracking can be performed without necessity ofany operation on the operation members 60 62 64 68 and 70 and the LCD 66 The embodiment can be preferably applied to a small sized camera such as a handy camera in which it is difficult to spare a space for installing the AF frame operation device If the space is not a problem and there is no influence on the operability confi
38. rtion which individually controls execution of the focus adjustment by the autofocus portion and execution of the tracking processing by the AF area tracking processing portion based on the depth of field calculated by the depth of field computing portion 2 The autofocus system as claimed in claim 1 wherein the control portion makes control not to execute the tracking processing when the depth of field is equal to or deeper than a predetermined threshold 3 The automatic system as claimed in claim 1 wherein the control portion makes control not to execute the focus adjust ment when infinity is included in the depth of field 4 The automatic system as claimed in claim 2 wherein the control portion makes control not to execute the focus adjust ment when infinity is included in the depth of field 5 The autofocus system as claimed in claim 1 wherein the depth of field computing portion calculates the depth of field based on information about diaphragm value object distance and focal distance obtained from the optical system 6 The autofocus system as claimed in claim 2 wherein the depth of field computing portion calculates the depth of field based on information about diaphragm value object distance and focal distance obtained from the optical system 7 The autofocus system as claimed in claim 3 wherein the depth of field computing portion calculates the depth of field based on information about diaphragm value object distance a
39. t 0004 As to focusing by AF focusing is generally per formed not on the entire screen of the captured image but on an object within an area autofocus area which is a part of the captured image That is in the contrast method focus adjust ment is performed to maximize the contrast of the captured image object image within the autofocus area 0005 An autofocus system with an automatic tracking function as shown in Patent Literature 1 is known as a system to achieve the autofocus function The autofocus system in Patent Literature 1 uses an AF mode in which either of a fixation mode to turn off the automatic tracking function and a tracking mode to turn on the automatic tracking function is selected by an operation of a user CITATION LIST Patent Literature 0006 Patent Literature 1 Japanese Patent No 4418344 SUMMARY OF INVENTION Problem to be Solved by the Invention 0007 Incidentally in the autofocus system with the auto matic tracking function mistracking is apt to occur when the angle of view is changed to a wide angle side by zooming in a state where automatic tracking is performed When the angle of view is then changed from the wide angle side to a telephoto side there is a possibility that another object than the intended object will be tracked 0008 Moreover even if an object within an autofocus area is in focus there is a possibility that the object will be out of focus when the angle of view is then
40. tracking processing by the AF area tracking processing portion based on the depth of field calculated by the depth of field comput ing portion Nov 14 2013 2 An autofocus system described in the paragraph 1 wherein 0120 the control portion makes control not to execute the tracking processing when the depth of field is smaller than a predetermined threshold 3 An automatic system described in the paragraph 1 or 2 wherein 0121 the control portion makes control not to execute the focus adjustment when the depth of field is infinite 4 An autofocus system according to any of the paragraphs 1 through 3 wherein 0122 the depth of field computing portion calculates the depth of field based on information about diaphragm value object distance and focal distance obtained from the optical system 5 An autofocus system according to any of the paragraphs 1 through 4 wherein 0123 the AF area tracking processing portion sets a human image within the autofocus area as a target to be tracked INDUSTRIAL APPLICABILITY 0124 The autofocus system according to the invention is provided with an automatic tracking function capable of sup pressing occurrence of mistracking when the angle of view is changed by zooming Accordingly the autofocus system is useful when it is applied to a digital camera especially a compact digital camera a camera including cellular phone a camera including electronic apparatus
41. ure returns to the processing of the step S12 0097 When the determination in the step S26 results in NO the CPU 38 determines whether an image of a reference pattern has moved or not that is whether an image range in which the reference patter has been detected is different from the currently set autofocus area or not step S28 Incidentally even in the case where the size of the image of the reference Nov 14 2013 pattern in the captured image has changed determination in the determination processing results in YES 0098 When the determination in the step S28 results in YES the procedure goes to the processing of the step S34 In the case where the determination in the step S28 results in NO the procedure goes to the processing of the step S36 0099 According to the aforementioned video camera sys tem 1 determination is made as to whether an image of a person s face is included in a captured image or not in the automatic tracking mode When determination is made that the image of the person s face is included in the captured image the image of the person s face is set as a target to be tracked and automatic tracking based on face detection pro cessing is executed When the angle of view is changed by zooming on that occasion determination is made as to whether execution of automatic tracking is allowed or not based on the depth of field When determination is made that execution of automatic tracking is not allowed a
42. ustment is allowed autofocus adjust ment is executed 0109 In addition according to the video camera system 1 the SPU 38 of the main board 30 determines whether execu tion of at least one of automatic tracking and autofocus adjust ment is allowed or not based on the depth of field When determination is made that the execution is not allowed con trol is made to stop the execution When control is made to automatically turn ON OFF automatic tracking and autofo cus adjustment mistracking can be prevented from occurring in the following case 0110 When there is an area in which the lens does not focus in a captured image and there is a moving object in the captured image and when sufficient contrast can be obtained from an image of the object within the autofocus area control is made to turn ON automatic tracking and turn ON AF 0111 There may be a case where the lens does not focus at any position of the captured image and there is an object which moves in the imaging range of the captured image In such a case it is assumed that execution of autofocus adjust ment is not necessary because the depth of field is infinite so that automatic tracking of the object is performed In such a case automatic tracking is controlled to be ON and autofocus adjustment is controlled to be OFF 0112 In the case where there is an area in which the lens does not focus in the captured image and the object as the target to be tracked is too small
43. utomatic tracking is automatically stopped When determination is made that execution of automatic tracking is allowed auto matic tracking is executed 0100 In addition the video camera system 1 can execute automatic tracking and control execution or stop of autofo cus adjustment based on the depth of field The video camera system 1 can control execution or stop of autofocus adjust ment in parallel with the aforementioned control of automatic tracking 0101 FIG 6 is a flow chart showing a processing proce dure when autofocus adjustment is controlled based on the depth of field 0102 When autofocus is executed the CPU 38 of the main board 30 brings the object into focus within the autofocus area set by the automatic tracking mode Successively the CPU 38 of the main board 30 acquires the diaphragm value the object distance and the focal distance from the lens device 12 step S40 0103 Then the CPU 38 of the main board 30 executes a computing process for calculating the depth of field by using data including the diaphragm value the object distance and the focal distance generated in the step S40 step S42 0104 Successively to the step S42 the CPU 38 of the main board 30 determines whether the depth of field calculated in the step S40 is infinite or not step S44 Here the fact that the depth of field is infinite means that infinity is included in the depth of field as a result of the computing 0105 When the deter
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