Abstract:
An adapter for controlling a first camera and a second camera, which exhibit differing operating characteristics, in a three-dimension ( 3 D) camera imaging system. The adapter provides a camera control signal to the first camera to control operation of the first camera. The adapter converts the camera control signal to a second camera control signal utilizing information from the first and the second cameras indicative of imaging states of the cameras, and provides the second camera control signal to the second camera to control operation of the second camera. The conversion compensates for the differing operating characteristics of the first and second cameras.

Description:
CONTINUATION INFORMATION 
       [0001]    The present application claims priority from Japanese Patent Application No. P2009-292607 filed on Dec. 24, 2009, the disclosure of which is incorporated herein by reference in its entirety. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a camera adaptor box and a camera control method that are suitable for use in applications in which 3D (three dimensional) images are generated from the images taken by two units of cameras, for example. 
         [0004]    2. Description of Related Art 
         [0005]    3D camera systems have been in use in which 3D images are obtained by combining the images separately taken by two different cameras. 
         [0006]    Referring to  FIG. 15 , there is shown an exemplary configuration of a related-art 3D camera system  101 . 
         [0007]    The 3D camera system  101  has two cameras  110   a  and  110   b,  control panels  111   a  and  111   b  for controlling the operation of each of the cameras  110   a  and  110   b,  and a monitor  112  on which images outputted from the cameras  110   a  and  110   b  are displayed. 
         [0008]    A reference signal is directly entered in each of cameras  110   a  and  110   b  and each of the cameras  110   a  and  110   b  directly outputs a taken image to an external apparatus. 
         [0009]    Referring to  FIG. 16 , there is shown an exemplary configuration of a related-art 3D camera system  102 . 
         [0010]    The 3D camera system  102  has camera control units  113   a  and  113   b  that are connected to cameras  110   a  and  110   b,  respectively, thereby outputting control signals to the camera  110   a  and  110   b  and outputting images received from the cameras  110   a  and  110   b . The cameras  110   a  and  110   b  are connected to the camera control units  113   a  and  113   b  with single link digital optical transmission paths capable of transmitting video signals at a transfer rate of 1.5 Gbps, for example. The camera control units  113   a  and  113   b  are also connected to a simultaneous control apparatus  114  configured to simultaneously control the operations of the camera  110   a  and camera  110   b.  From this simultaneous control apparatus  114 , the restricted functions of the cameras  110   a  and  110   b  can be simultaneously controlled. This function is intended to simultaneously control two or more system cameras; in this example, this function is applied to the control of the two cameras  110   a  and  110   b.    
         [0011]    Referring to  FIG. 17 , there is shown, an exemplary configuration of a related-art 3D camera system  103 . 
         [0012]    The 3D camera system  103  has a configuration in which two or more of the 3D camera systems  102  shown in  FIG. 16  are operated in parallel. Simultaneous control apparatuses  114   a  through  114   c  are arranged for the different 3D camera systems  102 , thereby controlling the cameras  110   a  and cameras  110   b  of each of these 3D camera systems  102 . 
         [0013]    However, the above-mentioned related-art technologies have no ability to simultaneously control the 3D cameras in one 3D camera system. 
       SUMMARY OF THE INVENTION 
       [0014]    It should be noted that generating a 3D image involves two images having different parallaxes. Typically, an engineer must operate not only the camera control units and the simultaneous control apparatus, but also adjust two cameras  110   a  and  110   b.  Therefore, the engineer needs to carry out the job that is approximately double when there is only one camera. 
         [0015]    For example, in relaying a sports program in a 3D manner, two or more 3D cameras must be arranged at various locations. In addition, because the camera adjustment is required during a relay operation, two or more cameras must be adjusted at the same time. However, the movements of subjects are generally quick in a sports program, for example. This not only requires engineers with high technical operation skills in executing image adjustment, but also makes the 3D camera system complicated, thereby increasing the operation work load. 
         [0016]    In consideration of the above-mentioned problems, the adjustment of the two cameras  110   a  and  110   b  is possible by camera linking capabilities such as master-slave realized by the simultaneous control apparatuses  114 ,  114   a  through  114   c,  for example. However, as shown in the 3D camera system  103 , operating two or more 3D camera systems  102  requires the installation of the same number of master-slave functions as the number of 3D cameras, the cameras  110   a  and  110   b,  on the 3D camera system  103 . This also causes a problem of increasing the system configuration. 
         [0017]    Further, use of a rig mechanism (or a half-mirror mechanism), one of mechanisms for arranging the cameras  110   a  and  110   b  in order to configure the 3D camera system  101 , requires the inversion of taken images. Therefore, use of a 3D camera system based on the rig mechanism requires matching the timing of taking a subject using the cameras  110   a  and  110   b  with the phase of video signals outputted by the cameras  110   a  and  110   b;  otherwise, the taken images are delayed to cause an incomplete resultant 3D image. 
         [0018]    Therefore, embodiments of the present invention addresses the above-identified and other problems associated with related-art methods. 
         [0019]    As described above, it is possible to set the difference of the second camera relative to the first camera, output the first control value to the first camera, and output a second control value with a difference corrected to a second camera in order to operate two units of cameras. 
         [0020]    This novel configuration saves the engineer the work of taking images for 3D imaging. In doing so, the two units of cameras output images that are homogenous to each other because the differences between these images are corrected. This novel configuration provides advantages of providing the output suitable for 3D images that are displayed by combining two images. 
         [0021]    Accordingly, one embodiment of the present invention is directed to an adapter for controlling a first camera and a second camera in a three-dimension (3D) camera imaging system. The first and second cameras exhibit differing operating characteristics and producing image signals. The adapter includes a source of a camera control signal to control predetermined operations of the first camera; and a converter for converting the camera control signal to a second camera control signal to control said predetermined operations of said second camera, said converter compensating for said differing operating characteristics of said first and second cameras. 
         [0022]    Another embodiment of the present invention is directed to the adapter described above and also including an output for supplying image signals picked up by the first camera and the second camera. 
         [0023]    Another embodiment of the present invention is directed to the adapter described above and the first camera and the second camera are controlled substantially simultaneously. 
         [0024]    Another embodiment of the present invention is directed to the adapter described above and a processing unit for receiving an initial first control value and an initial second control value. 
         [0025]    Another embodiment of the present invention is directed to the adapter described above and wherein the adapter sends the initial first control value to the first camera and the initial second control value to the second camera, and wherein the processing unit calculates differential data as a function of (1) information indicative of an imaging state of the first camera and (2) information indicative of an imaging state of the second camera. 
         [0026]    Another embodiment of the present invention is directed to the adapter described above and also includes a storage unit for storing the differential data. 
         [0027]    Another embodiment of the present invention is directed to the adapter described above and the converter utilizes the differential data for compensating for the differing operating characteristics of the first camera and the second camera. 
         [0028]    Another embodiment of the present invention is directed to the adapter described above and the processing unit generates a corrected control value as a function of the differential data. 
         [0029]    Another embodiment of the present invention is directed to the adapter described above and the source of the camera control signal sends the camera control signal to the first camera and sends a corrected control signal to the second camera, and the corrected control signal is a function of the corrected control value. 
         [0030]    Another embodiment of the present invention is directed to the adapter described above and the camera control signal controls an iris adjust value, aperture, zoom, camera direction, setting positions, or timing. 
         [0031]    Another embodiment of the present invention is directed to the adapter described above and a difference in the image signals supplied by the first camera and the second camera are utilized in converting the camera control signal to the second camera control signal to control the predetermined operations of the second camera. 
         [0032]    Another embodiment of the present invention is directed to the adapter described above and images from the first camera and second camera are supplied to a viewfinder, and a difference in the supplied image to the viewfinder by the first camera and the second cameras are utilized in converting the camera control signal to the second camera control signal to control the predetermined operations of the second camera. 
         [0033]    Another embodiment of the present invention is directed to the adapter described above and also includes a timing generation circuit for generating a first timing signal and a second timing signal for controlling operation of the first camera and the second camera simultaneously. 
         [0034]    Another embodiment of the present invention is directed to a method of operating a camera system described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0035]      FIG. 1  is a schematic diagram illustrating an exemplary configuration of a 3D camera system made up of camera heads and a camera adaptor box practiced as one embodiment of the invention; 
           [0036]      FIG. 2  is a schematic diagram illustrating an exemplary configuration of a 3D camera system in which a camera control unit is added to the 3D camera system shown in  FIG. 1 ; 
           [0037]      FIG. 3  is a schematic diagram illustrating an exemplary configuration of a 3D camera system in which the two or more 3D camera systems shown in  FIG. 2  are arranged in parallel; 
           [0038]      FIGS. 4A and 4B  are schematic diagrams illustrating an exemplary camera mount on which the two 3D cameras shown in  FIG. 1  are mounted; 
           [0039]      FIG. 5  is a block diagram illustrating an exemplary internal configuration of the 3D camera system shown in  FIG. 1 ; 
           [0040]      FIG. 6  is a block diagram illustrating an exemplary internal configuration of a camera adaptor box shown in  FIG. 1 ; 
           [0041]      FIG. 7  is a block diagram illustrating an exemplary internal configuration of a video interface block shown in  FIG. 5 ; 
           [0042]      FIG. 8  is a block diagram illustrating exemplary internal configurations of the camera adaptor box and camera heads shown in  FIG. 1 ; 
           [0043]      FIGS. 9A and 9B  are pictures indicative of exemplary images taken by scan lines in the embodiment shown in  FIG. 1 ; 
           [0044]      FIG. 10  is a graph indicative of an exemplary relation between iris adjustment value and iris aperture in the cameras shown in  FIG. 1 ; 
           [0045]      FIG. 11  is a graph indicative of an example of correcting the iris aperture of the cameras shown in  FIG. 1  by use of a correction function; 
           [0046]      FIG. 12  is a graph indicative of an example of correcting the iris aperture of the cameras shown in  FIG. 1  by use of a correction function approximating a line plot; 
           [0047]      FIGS. 13A ,  13 B, and  13 C are pictures indicative of display examples of images shown on a viewfinder block shown in  FIG. 1 ; 
           [0048]      FIGS. 14A ,  14 B, and  14 C are pictures indicative of display examples shown on the viewfinder block shown in  FIG. 1 ; 
           [0049]      FIG. 15  is a schematic diagram illustrating a related-art 3D camera system; 
           [0050]      FIG. 16  is a schematic diagram illustrating another related-art 3D camera system; and 
           [0051]      FIG. 17  is a schematic diagram illustrating still another related-art 3D camera system. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0052]    It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the present invention, while eliminating, for purposes of clarity, many other elements which are conventional in this art. Those of ordinary skill in the art will recognize that other elements are desirable for implementing the present invention. However, because such elements are well known in the art, and because they do not facilitate a better understanding of the present invention, a discussion of such elements is not provided herein. 
         [0053]    The present invention will now be described in detail on the basis of exemplary embodiments. 
         [0054]    This invention will be described in further detail by way of embodiments thereof with reference to the accompanying drawings. The description will be made in the following order. 
         [0055]    1. One embodiment of the invention (a camera control function; namely, an example in which two or more camera heads are used for a 3D camera system). 
         [0056]    2. Variations to the above-mentioned embodiment. 
         [0057]    One Embodiment of the Invention 
         [0058]    The following describes one embodiment of the present invention with reference to  FIGS. 1 through 14 . With one embodiment of the invention, examples of 3D camera systems each having a camera adaptor box  12  configured to output images taken by two camera heads  10   a  and  10   b  to an external apparatus by giving image taking instructions to these camera heads  10   a  and  10   b.    
         [0059]    Now, referring to  FIG. 1 , there is shown an exemplary configuration of a 3D camera system  1 . 
         [0060]    The 3D camera system  1  has an optical system, an image device, and other elements, not shown, and has a camera head  10   a  and a camera head  10   b  that are configured to output images of a taken subject. It should be noted that the camera head  10   a  and the camera head  10   b  are fixed on a wall for example and have no function of recording taken images. 
         [0061]    In the following description, it is assumed that an image outputted by the camera head  10   a  may be used for the right channel (or the right eye) and an image outputted by the camera head  10   b  be used for the left channel (or the left eye). 
         [0062]    Further, the 3D camera system  1  has a camera adaptor box (CAB)  12  configured to control the operations of the camera head  10   a  and the camera head  10   b  to execute predetermined processing on the images received from the camera head  10   a  and the camera head  10   b,  thereby outputting the processed images. The camera adaptor box  12  has a viewfinder block  13  configured to display the images of a subject taken by the camera head  10   a  and the camera head  10   b,  under the control of a video interface block  24  (refer to  FIG. 5  below). 
         [0063]    Referring to  FIG. 2 , there is shown an exemplary configuration of a 3D camera system  2 . 
         [0064]    The 3D camera system  2  has a camera head  10   a  and a camera head  10   b,  a camera adaptor box  12 , and a camera control unit (CCU)  14  that is connected to the camera adaptor box  12  via a camera cable  15 . For the camera cable  15 , a wide-band digital optical transmission path capable of transmitting massive amounts of optical digital signals. In this example, as compared with a related-art 1.5 Gbps data rate, embodiments of the present invention assume an optical data transmission rate of 3.7 Gbps. It should be noted here that embodiments of the present invention allow video data compression to realize narrow-band transmission. 
         [0065]    The camera adaptor box  12  collects images outputted from the camera heads  10   a  and  10   b  and transmits these images to the camera control unit  14  over the camera cable  15 . The camera adaptor box  12  executes processing, such as inverting images entered from the camera heads  10   a  and  10   b  and delaying an output signal so as to provide signal in-phasing. 
         [0066]    Between the camera control unit  14  and the camera adaptor box  12 , a wideband (more than double a related-art band) communication interface is used. This interface can simultaneously transmit the images outputted from the camera heads  10   a  and  10   b.  In addition, the camera control unit  14  has a communication interface compliant with 3G-HDI for example through which the camera control unit  14  can transfer video signals to an external device at high speeds. The camera control unit  14  outputs a control signal received from the a control panel  11  to the camera adaptor box  12  and outputs a video signal received from the camera adaptor box  12  to a display apparatus and a recording apparatus, not shown. Further, the camera control unit  14  is controlled by the control panel  11  operated by an engineer. 
         [0067]    As described above, because the camera adaptor box  12  is arranged between the camera heads  10   a  and  10   b  and the camera control unit  14 , it appears that, from the camera adaptor box  12 , the operation of one camera is being controlled from the camera adaptor box  12 . 
         [0068]    Referring to  FIG. 3 , there is shown an exemplary configuration of a 3D camera system  3 . 
         [0069]    The 3D camera system  3  is configured in which the 3D camera systems  2  shown in  FIG. 2  are operated in parallel. The camera control unit  14  is arranged for each of the 3D camera systems  2 . The operation timing between the camera heads  10   a  and  10   b  arranged for each 3D camera system  2  is controlled. 
         [0070]    The camera control unit  14  is also connected to a simultaneous control apparatus  6  that simultaneously controls the operations of the camera heads  10   a  and  10   b  arranged for the 3D camera system  2  that are operated in parallel. The camera adaptor box  12  can differentiate a control value by a difference in the operation of the camera head  10   b  for the camera head  10   a,  thereby controlling the operations of the camera heads  10   a  and  10   b  as if these cameras are one unit of the camera. Consequently, 3D camera systems  101  through  103 , the 3D camera system  3  can be simplified in configuration. The camera head  10   a,  the camera head  10   b,  the camera adaptor box  12 , the camera control unit  14 , and the simultaneous control apparatus  6  are interconnected by a network. The connection between these components is realized by coaxial cables, triaxial cables, optical fiber cables, wireless communication, and other communication media. 
         [0071]    Referring to  FIGS. 4A and 4B , there is shown an exemplary configuration of a mount (RIG)  7  on which the camera heads  10   a  and  10   b  are mounted. 
         [0072]      FIG. 4A  shows an exemplary configuration of the camera heads  10   a  and  10   b  when the mount  7  is viewed from one side. 
         [0073]    If the camera heads  10   a  and  10   b  are arranged with the zoom of the camera heads  10   a  and  10   b  to equal one and a lens distance thereof matched with the human eye, a 3D image obtained from the images taken the camera heads  10   a  and  10   b  thus arranged looks natural. However, because the housings of the camera heads  10   a  and  10   b  are relatively large and, if the camera heads  10   a  and  10   b  are arranged side by side for imaging, a subject is taken with a parallax wider than that of the human eyes, resulting in an unnatural 3D image. Hence, the mount  7  has a half mirror  8 . The first camera head  10   a  is arranged at a position where the image of a subject is directly enters through the half mirror  8 . The second camera head  10   b  is arranged at a position where the image of the subject enters after being reflected from the half mirror  8 . Thus, the camera heads  10   a  and  10   b  are arranged such that the optical axes of the lenses of the camera heads  10   a  and  10   b  vertically cross each other. 
         [0074]      FIG. 4B  shows an example of how the half mirror  8  looks when viewed from the direction of arrow  9 . The camera heads  10   a  and  10   b  are arranged on the mount  7  by shifting from each other in a distance obtained by the parallax of the human eyes. Hence, the lens of the camera head  10   a  looking through the half mirror  8  and the lens of the camera head  10   b  looking as reflected from the half mirror  8  are shifted from each other in the horizontal direction. Thus, arranging the half mirror  8  on the mount  7  allows the installation of the camera heads  10   a  and  10   b  to match with the parallax of the human eyes, thereby producing a natural looking 3D image. 
         [0075]    Referring to  FIG. 5 , there is shown an exemplary internal configuration of the 3D camera system  2 . 
         [0076]    The camera head  10   a  has an imaging device  16  that outputs a video signal. The imaging device  16  is made up of a CCD (Charge Coupled Device) imager or a CMOS (Complementary Metal Oxide Semiconductor) sensor, for example. 
         [0077]    The camera head  10   a  has a PLL (Phase Locked Loop) circuit  17  for executing a PLL operation under the control of the camera adaptor box  12  and a timing generation circuit  18  for generating an imaging timing signal of the imaging device  16  by a PLL operation of the PLL circuit  17 . In addition, the camera head  10   a  has a CPU  19   a  for controlling each of the components of the camera system and a video processor  20  that executes predetermined processing on a video signal outputted from the imaging device  16  to output the processed video signal to the camera adaptor box  12 . 
         [0078]    It should be noted that the camera head  10   b  is generally the same in configuration as the camera head  10   a  except a CPU  19   b  instead of the CPU  19   a.  Therefore, the similar components of the camera head  10   b  are denoted by the same reference numbers as those of the camera head  10   a  and the description of the similar components will be skipped for the brevity of description. 
         [0079]    The camera adaptor box  12  has a PLL circuit  21  for executing a PLL operation under the control of the camera control unit  14  and a timing generation circuit  22  for generating an imaging timing signal for controlling the imaging timings of the camera heads  10   a  and  10   b  by a PLL operation of the PLL circuit  21 . In addition, the camera adaptor box  12  has a CPU  23  for controlling each component of the camera adaptor box  12 , a video interface block  24  for executing predetermined processing on the video signals supplied from the camera heads  10   a  and  10   b  to output the processed signals to the camera control unit  14 , and a viewfinder block  13 . A viewfinder signal is supplied to the viewfinder block  13  from the video interface block  24 . The images of a subject are shown on the camera heads  10   a  and  10   b,  allowing the engineer to check the taken images (refer to  FIGS. 13A to 14C  to be described later). 
         [0080]    The camera control unit  14  has a PLL circuit  31  that executes a PLL operation on the basis of a reference signal supplied from an external apparatus, not shown, and a timing generation circuit  32  that generates a timing signal for controlling the operation timing of the camera adaptor box  12  by a PLL operation of the PLL circuit  31 . In addition, the camera control unit  14  has a CPU  33  that controls the processing of each component of the camera control unit  14  in cooperation with the CPU  23  of the camera adaptor box  12  and a video interface  34  that executes predetermined processing on the video signal supplied from the camera adaptor box  12  to output the processed video signal to an external apparatus, not shown. 
         [0081]    The following describes the operation of each component mentioned above. 
         [0082]    The CPU  33  of the camera control unit  14  functions as an instruction value output block that outputs instruction values for instructing the CPU  23  to instruct the operations of the camera heads  10   a  and  10   b,  these instruction values serving as the basis for the first and second control values. Then, the video interface  34  of the camera control unit  14  outputs the images received from the video interface block  24  of the camera adaptor box  12  to an external apparatus, not shown. 
         [0083]    The CPU  23  of the camera adaptor box  12  receives command signals of one line that are transmitted in a multiplexed manner from the camera control unit  14  through the camera cable  15 . Then, the CPU  23  outputs the first and second control values that almost equalize the change ratio of imaging operations such as aperture and white balance of the camera heads  10   a  and  10   b  to the camera heads  10   a  and  10   b.    
         [0084]    Thus, the camera adaptor box  12  includes the following control values in a received command signal and outputs this command signal to the camera heads  10   a  and  10   b.  On the basis of the information indicative of the imaging state at the time the camera heads  10   a  and  10   b  execute imaging operations, the CPU  23  sets the differential data between the first camera and the second camera beforehand by the first and second control values outputted to the camera heads  10   a  and  10   b.  The CPU  23  stores the differential data between the camera heads  10   a  and  10   b  and, by use of this differential data, functions as a correction control block for outputting the first control value to the first camera head  10   a  and the second control value obtained by correcting the differential data to the second camera head  10   b.  As a result, the camera heads  10   a  and  10   b  can be handled as if these camera heads were one unit of camera by applying the differential data to the control command to be received from the camera control unit  14 . 
         [0085]    With the camera adaptor box  12 , a voltage control oscillator of the PLL circuit  21  is PLL-locked on the basis of a reference signal received from the camera control unit  14 . The timing generation circuit  22  functions as an imaging timing adjustment block that outputs an imaging timing signal for adjusting the imaging timings of the camera heads  10   a  and  10   b  to the PLL circuit  17  of the camera heads  10   a  and  10   b.  This allows matching between the imaging timings of the camera heads  10   a  and  10   b.  The timing generation circuit  22  generates imaging timing signals (T 1  and T 2 ) for use by the camera heads  10   a  and  10   b,  respectively. If a misalignment occurs between the imaging timing signals (T 1  and T 2 ) in the two cameras as a 3D image due to camera image inversion processing for example, the imaging timing signals (T 1  and T 2 ) can be shifted together to correct the misalignment. 
         [0086]    As shown in  FIG. 4 , if the mount  7  is of a rig type with image inversion, it is helpful to match both the imaging timings of the camera heads  10   a  and  10   b  and the video output timings. Therefore, the camera adaptor box  12  has an image delay function in addition to the image inversion function. It should be noted that, along with the image inversion function, the image delay function may be installed on the camera heads  10   a  and  10   b  or the camera adaptor box  12 . 
         [0087]    When the camera heads  10   a  and  10   b  receives imaging timing signals, the PLL circuit  17  executes a PLL operation on each camera head in a proper phase. Hence, in the system operation, the two camera heads  10   a  and  10   b  are simultaneously controlled, thereby allowing the camera adaptor box  12  to operate as if one unit of camera. 
         [0088]    The video interface block  24  of the camera adaptor box  12  functions as a video output block that outputs images received from the camera heads  10   a  and  10   b  which executed imaging operations on the basis of the first and second control values with the imaging timings adjusted by imaging timing signals. If the imaging device  16  is a CMOS sensor based on line scan imaging (the CCD imager is of image planar scanning), then the camera heads  10   a  and  10   b  each have a function of changing the sequence of up/down directions at the time when an image is inverted in the up/down directions. Hence, the camera adaptor box  12  can adjust the image distortion direction caused by a rolling shutter effect. 
         [0089]    The video interface block  24  vertically inverts the image received from one of the camera heads  10   a  and  10   b  in match with the image received from the other camera head and outputs a resultant image. 
         [0090]    Next, the timing generation circuit  22  outputs an imaging timing signal to the other camera head by delaying the imaging timing by one frame. 
         [0091]    In addition, the camera adaptor box  12  can select, as a viewfinder signal, an output from the camera head  10   a,  an output from the camera head  10   b , a mixed output from both the camera heads  10   a  and  10   b,  or a differential output from the camera head  10   a  to the camera head  10   b  and display the selected signal. Display examples of this outputted image will be described later (with reference to  FIGS. 13A to 14C ). 
         [0092]    Further, the camera adaptor box  12  has a function of switching between the main line and the return signal to output a viewfinder signal to the viewfinder block  13 . If the viewfinder block  13  is compatible with 3D image display, the viewfinder block  13  can receive a 3D viewfinder signal from the video interface block  24  to display a 3D image. In this case, the video interface block  24  can add characters (or character information) and markers, for example, that are displayed on the viewfinder block  13  to the viewfinder signal so as to display these characters and markers in a 3D manner. For this purpose, the camera adaptor box  12  can set characters and markers at any distances by putting these characters and markers into the consideration of 3D perspective effect. 
         [0093]    It should be noted that, for an exemplary application, the differential data for camera control may not be stored in the camera adaptor box  12 . For example, the differential data may be stored in the camera head  10   a  or the camera head  10   b  to manipulate, inside the camera head  10   a  or the camera head  10   b,  the control data (or commands) supplied from the camera control unit  14 . Control items include camera control items, such as iris, white balance, pedestal, gamma, filter, flair, black gamma, knee, and saturation and others. 
         [0094]    Referring to  FIG. 6 , there is shown an exemplary internal configuration of the camera adaptor box  12 . 
         [0095]    The camera adaptor box  12  has a reception block  27  for receiving command signals entered over the camera cable  5  and a transmission block  28  for transmitting video signals received from the camera heads  10   a  and  10   b  to the camera control unit  14 . 
         [0096]    Further, the camera adaptor box  12  has a timing generation circuit  22  for generating imaging timing signals (T 1  and T 2 ) for substantially simultaneously controlling the camera heads  10   a  and  10   b  by a PLL operation of the PLL circuit  21 . In addition, the camera adaptor box  12  has genlock circuits  29   a  and  29   b  for transmitting imaging timing signals (T 1  and T 2 ) to the camera heads  10   a  and  10   b  with predetermined timings, thereby genlocking the camera heads  10   a  and  10   b.    
         [0097]    In addition, the camera adaptor box  12  has a video interface block  24  for receiving video signals (C 1  and C 2 ) from the camera heads  10   a  and  10   b  and transmitting a viewfinder signal to the viewfinder block  13  and transmitting the video signals (C 1  and C 2 ) to a video interface block  26  in the next stage. 
         [0098]    The video interface block  24  outputs, to the viewfinder block, any one of an image outputted from the camera head  10   a,  an image outputted from the camera head  10   b,  a mixed image outputted from the camera heads  10   a  and  10   b,  a differential image obtained by subtracting the image outputted from the camera head  10   b  from the image outputted from the camera head  10   a,  divided images obtained by dividing the images outputted from the camera heads  10   a  and  10   b  at the center of screen, the divided images being substantially simultaneously displayed, and a 3D image. 
         [0099]    Further, the camera adaptor box  12  has the video interface block  26  for transmitting a reference signal received by the reception block  27  to the PLL circuit  21 , transmitting a return signal to the video interface block  24 , and transmitting and receiving command signals with the CPU  23 . The video interface block  26  also has a function of transmitting video signals (C 1  and C 2 ) received from the video interface block  24  to a transmission block  28 . 
         [0100]    Referring to  FIG. 7 , there is shown an exemplary internal configuration of the video interface block  24 . 
         [0101]    The video interface block  24  has FIFO memories  31   a  and  31   b  for storing video signals entered from the camera heads  10   a  and  10   b,  respectively, in a first-in first-out basis, memories  33   a  and  33   b  for temporarily storing video signals read from the FIFO memories  31   a  and  31   b,  and filter blocks  32   a  and  32   b  for appropriately accessing the memories  33   a  and  33   b  to horizontally and vertically filter the video signals. The video interface block  24  also has the video interface  34  for outputting the video signals (C 1  and C 2 ) received from the filter blocks  32   a  and  32   b  to the video interface block  26 . The video interface  34  also has a function as a selector for selecting one of the video signals (C 1  and C 2 ) to be outputted to the video interface block  26 . 
         [0102]    In addition, the video interface  34  has a viewfinder signal processor  35  for generating viewfinder signals outputted to the viewfinder block  13  by the video signals received from the filter blocks  32   a  and  32   b.  The viewfinder signals are outputted to the viewfinder block  13 . The viewfinder block  13  displays various viewfinder images accordingly. 
         [0103]    The video interface block  24  has a FIFO memory  36  for storing a return signal received from the video interface block  26 , on a first-in first-out basis. The return signal read from the FIFO memory  36  is transmitted to the video interface  34  for use in a predetermined processing operation. 
         [0104]    Referring to  FIG. 8 , there is shown an exemplary internal configuration of the CPU  19   a  of the camera head  10   a,  the CPU  10   b  of the camera head  10   b,  and the CPU  23  of the camera adaptor box  12 . 
         [0105]    The CPU  23  of the camera adaptor box  12  has camera adaptor data  41  for controlling operations of the camera adaptor box  12 , a correction processing block  43  for executing correction by predetermined correction functions, and correction data  42  that is entered in the correction processing block  43 . The camera adaptor data  41  and the correction data  42  are stored in a memory, not shown. 
         [0106]    The CPUs  19   a  and  19   b  of the camera heads  10   a  and  10   b  have camera data  45   a  and  45   b  for providing data unique to the camera heads  10   a  and  10   b  on the basis of the control signals received from the CPU  23 , and trim data  46   a  and  46   b  for correcting the individual differences of the camera heads  10   a  and  10   b,  respectively. In addition, the CPUs  19   a  and  19   b  has adding blocks  47   a  and  47   b  for adding the trim data  46   a  and  46   b  to each control signal and a DSP (Digital Signal Processor)  48   a  and DSP  48   b  for controlling operations of the components of the camera heads  10   a  and  10   b  on the basis of control signals received from the adding block  47   a  and  47   b.    
         [0107]    The following describes each of the above-mentioned components. 
         [0108]    First, the control panel  11  outputs a control signal to the camera adaptor box  12 , thereby outputting a predetermined control command. Next, the CPU  23  stores the command received from the control panel  11  into camera adaptor data  41  and controls the camera head  10   a  as instructed by the stored command. It should be noted here that the operations of the camera heads  10   a  and  10   b  in mechanism or software may not actually match each other even if the imaging conditions of the camera heads  10   a  and  10   b  are equal between the camera heads  10   a  and  10   b.  A mismatch between the operations of the camera heads  10   a  and  10   b  is referred to a “difference.” The camera adaptor box  12  eliminates this difference to prevent the images taken by the camera heads  10   a  and  10   b  from being shifted. 
         [0109]    The camera adaptor box  12  has correction data  42  for correcting the difference between the camera heads  10   a  and  10   b.  On the basis of the operation of the camera head  10   a,  the difference to the operation of the camera head  10   b  relative to the operation of the camera head  10   a  is corrected by the correction processing block  43 . Consequently, the camera adaptor box  12  corrects the command from the control panel  11  by a given function, thereby controlling the camera head  10   b.  For example, the correction processing block  43  can correct the irises of the camera heads  10   a  and  10   b  by use of a correction function to be described later. 
         [0110]    Hence, the control signal for operating the camera head  10   a  is outputted to the camera head  10   a  without being corrected by the camera adaptor box  12 . The CPU  19   a  in the camera head  10   a  corrects the command issued from the control panel  11  by given camera data  45   a  and trim data  46   a  to the control signal and then outputs a command to the DSP  48   a.  Consequently, the DSP  48   a  controls the operation of the camera head  10   a.    
         [0111]    On the other hand, the control signal corrected by the correction processing block  43  is outputted to the camera head  10   b.  The CPU  19   b  in the camera head  10   b  gives camera data and adjustment data to the control signal to correct the command issued from the control panel  11  and outputs the corrected command to the DSP  48   b.  Consequently, the DSP  48   b  controls the operation of the camera head  10   b.    
         [0112]    The camera heads  10   a  and  10   b  installed on the mount  7  are arranged so that the lens optical axes cross each other at right angles as shown in  FIG. 4  and the camera head  10   a  outputs a video signal with up/down and left/right directions aligned relative to a subject. However, the camera head  10   b  is arranged with the imaging direction in which imaging is done by the camera head  10   b  inverted. Therefore, the images outputted by the camera heads  10   a  and  10   b  are inverted in the vertical image (depending on the installation, the image in the horizontal direction may be inverted). 
         [0113]    Therefore, if the vertical direction is inverted, the video interface block  24  in the camera adaptor box  12  delays the output of the video signal received from the camera head  10   a  by a time equivalent to one field and outputs the delayed signal. On the other hand, because the line scan of the video signal received from the camera head  10   b  is opposite in direction with the line scan of the video signal received from the camera head  10   a,  the video interface block  24  makes adjustment so that one field of the video signal is stored and outputted by substantially the similar line scan to the video signal received from the camera head  10   a.  This processing allows the camera adaptor box  12  to provide synchronization between the frames of the video signals received from the camera heads  10   a  and  10   b  and output the synchronized video signals to the camera control unit  14 . 
         [0114]    Referring to  FIGS. 9A and 9B , there are shown examples in which matches are made between the imaging timings and video output timings of the camera heads  10   a  and  10   b  by changing scan directions if the camera heads  10   a  and  10   b  are of sequential scan type as CMOS sensors. 
         [0115]      FIG. 9A  shows an image being taken by the camera head  10   a,  then  FIG. 9B  shows an image being taken by the camera head  10   b.  At this moment, the vertical scan sequence of the camera head  10   b  may be inverted to make the imaging time of the image match that of the camera head  10   a  and also match the video output timing (the camera head  10   b  has a function of setting scan directions as desired). 
         [0116]      FIGS. 10 through 12  show examples of correction functions that are used by the correction processing block  43  to correct the iris of the camera head  10   b.    
         [0117]    Referring to  FIG. 10 , there is shown an example of iris adjustment values to be given to the camera heads  10   a  and  10   b  and actual iris apertures. 
         [0118]    First, an iris control signal is transmitted from the control panel  11  to the camera adaptor box  12  via the camera control unit  14 . This iris control signal is used for an iris adjustment value for adjusting the irises of the camera heads  10   a  and  10   b.    
         [0119]    It is desired here that the iris adjustment value indicated by the camera control unit  14  and the iris aperture value at the time the irises of the camera heads  10   a  and  10   b  are actually driven change ideally along a line  50 . However, the figure is indicative that the iris aperture of the camera head  10   a  changes along a correction function  51  and the iris aperture of the camera head  10   b  changes along a line  52 . Hence, there may occur a difference between the iris apertures of the camera heads  10   a  and  10   b  relative to the iris adjustment value, thereby resulting in differences in luminance and so on of the taken image. Therefore, by use of a correction curve shown in  FIG. 11 , the CPU  23  converts the iris adjustment value transmitted to the camera head  10   b  into the control value of the iris adjustment value transmitted to the camera head  10   a.    
         [0120]    Referring to  FIG. 11 , there is shown an example of iris adjustment values to be given to the camera heads  10   a  and  10   b.    
         [0121]    As described above, although the same iris adjustment value is used on the camera heads  10   a  and  10   b,  the camera heads  10   a  and  10   b  use different iris apertures. Hence, with reference to the camera head  10   a,  the degree of change for the camera head  10   b  is defined by a curve correction function. The values of the correction function changes from time to time depending on the correction data  42 . As shown in the figure, the change in the iris adjustment value to be given to the camera head  10   b  can be made go along a correction function  51  indicative of the change in the iris adjustment value to be given to the camera head  10   a,  thereby operating the camera heads  10   a  and  10   b  with a same iris aperture. 
         [0122]    Referring to  FIG. 12 , there is shown an example of iris adjustment values to be given to the camera heads  10   a  and  10   b.    
         [0123]    The correction function  51  shown in  FIG. 12  is generally the same as the correction function  51  shown in  FIG. 11  except for plots  53   a  through  55   a  specified on the correction function  51  shown in  FIG. 10  that are for approximating the correction  51  with a dotted line. The correction values of the iris adjustment values of the camera heads  10   a  and  10   b  are measured in advance, and then the correction function is approximated by the dotted line on the basis of the measured correction values. At this moment, plots  53   b  through  55   b  in the iris adjustment value to be given to the camera head  10   b  are corrected in match with the plots  53   a  through  55   a,  respectively. 
         [0124]      FIGS. 13A to 14C  show examples of images that are displayed on the viewfinder block  13 . 
         [0125]    The camera adaptor box  12  can select, as a viewfinder signal, an output image of the camera head  10   a,  an output image of the camera head  10   b,  a mixed output image of the camera heads  10   a  and  10   b,  and a differential image between the output images of the camera heads  10   a  and  10   b  and display the selected image on the viewfinder block  13 . 
         [0126]    Then, the engineer can operate a menu interface displayed on the viewfinder block  13 , a rotary switch attached to the camera adaptor box  12 , or allocate push switches or sequentially operate the push switches, thereby selecting images to be displayed on the viewfinder block  13 . The engineer can also switch an image to be displayed on the viewfinder block  13  to a return signal in response to a request for receiving from the camera control unit  14  or the like, thereby outputting the return signal. In addition, if the viewfinder block  13  is compatible with 3D image display, the engineer can display images for two channels outputted from the left and right channels and add a selection menu for this purpose. 
         [0127]      FIG. 13A  shows an example of an image of the right channel that is outputted from the camera head  10   a.    
         [0128]      FIG. 13B  shows an example of an image of the left channel that is outputted from the camera head  10   b.    
         [0129]    Because the camera heads  10   a  and  10   b  are arranged on the mount  7  in match with the parallax of user, a horizontal shift is observed between the images of the right channel and the left channel. 
         [0130]      FIG. 13C  shows an example of a mixed image obtained by mixing the images outputted from the camera heads  10   a  and  10   b.    
         [0131]    A mixed image is obtained by adding a luminance signal and a chrominance signal (Lch_Y, Lch_CB, Lch_CR) of the camera head  10   b  (the left channel) to a luminance signal and a chrominance signal (Lch_Y, Rch_CB, Rch_CR) of the camera head  10   a  (the right channel). This mixed signal is colored. 
         [0132]      FIG. 14A  shows an example of a differential image. 
         [0133]    A differential image is a gray image obtained by subtracting a video signal outputted from the camera head  10   a  from a video signal outputted from the camera head  10   a.    FIG. 14A  shows a differential image obtained by taking a video chart. At this moment, the video interface block  24  displays the differential image on the viewfinder block  13  on the basis of a difference between the luminance signal or chrominance signal of an image taken by the camera head  10   a  and the luminance signal or chrominance signal taken by the camera head  10   b.    
         [0134]    The differential image is obtained by subtracting the luminance signal (Rch_Video) of the camera head  10   a  (the right channel) from the luminance signal (Lch_Video) of the camera head  10   b  (the left channel). It is also practicable to subtract the luminance signal of the camera head  10   b  (the left channel) from the luminance signal of the camera head  10   a  (the right channel). Then, an obtained differential value is divided by  2  or another proper number and a result of the division is added with a video level (50_Video_Level) of a proper value as an offset. 
         [0135]    The above-mentioned explanation can be expressed as follows: 
         [0136]    (Lch_Video−Rch_Video)/2+50_Video_Level 
         [0137]    As a result, a differential image with attention put only on luminance can be displayed on the viewfinder block  13 . 
         [0138]    Likewise, it is practicable to create differential data on the basis of chrominance data. At this time, a difference is obtained by subtracting a chrominance signal (Rch_CB, Rch_CR) of the camera head  10   a  (the right channel) from a chrominance signal (Lch_CB, Lch_CR) of the camera head  10   b  (the left channel). 
         [0139]    (Lch_CB−Rch_CB)/2 or (Lch_CR−Rch_CB)/2 
         [0140]    It should be noted, however, that, because point 0 is the intermediate point, an offset value need not be added in this case. For highlighted display, color intensification may be made by the multiplication by a proper value without the division by 2. 
         [0141]    Thus, a monochrome mode in which only luminance is displayed as a differential image and a color mode in which chrominance data is added can be displayed on the viewfinder block  13 . 
         [0142]    If the zoom and direction of the camera heads  10   a  and  10   b  are correctly arranged, there occurs no shift in video, so that a resultant differential image is in an ideal state in which no outline is displayed. However, if there is a difference between the arrangements of the camera heads  10   a  and  10   b,  there occurs a shift between the two images, resulting in the enhanced outline of the subject as shown on the left side in  FIG. 14A . This provides information that is effective in correctly setting the zoom and direction of the camera heads  10   a  and  10   b  set on the mount  7 . 
         [0143]      FIG. 14B  shows an example of an anaglyph image. 
         [0144]    The anaglyph image is used to provide a 3D image. For example, through a red cellophane film for the left eye and a blue cellophane film for the right eye, the user can get a 3D image effect. 
         [0145]      FIG. 14C  shows an example of divided image obtained by dividing images. 
         [0146]    In this example, the right half of an image outputted from the camera head  10   a  and the left half of an image outputted from the camera head  10   b  are connected with each other at the centers thereof, the resultant image being displayed. This allows the engineer to understand distortions and the like of the installation positions of the camera heads  10   a  and  10   b,  making it easy to align the distortions in the horizontal direction. It should be noted that, although not shown, the upper half of an image outputted from the camera head  10   a  and the lower half of an image outputted from the camera head  10   b  may be connected with each other at the center thereof. In this case, it becomes easy to align the distortion in the vertical direction of the camera heads  10   a  and  10   b.    
         [0147]    According to the above-described camera adaptor box  12  practiced as one embodiment of the invention, a differential value of an operation of the camera head  10   b  relative to the camera head  10   a  is obtained with reference to an operation of the camera head  10   a.  Then, the operation of the camera head  10   b  is controlled on the basis of the differential value. Consequently, in outputting, from the control panel  11 , a control signal for the camera adaptor box  12  to control operations of the camera heads  10   a  and  10   b,  the engineer can control the two units of the camera heads  10   a  and  10   b  as if the camera heads  10   a  and  10   b  were one unit of camera head. In addition, because the camera heads connected to the camera adaptor box  12  look like one unit from the camera control unit  14  constituting the camera systems  2  and  3 , the configuration of the camera systems  2  and  3  will not be complicated. Further, the camera heads  10   a  and  10   b  output the homogeneous images with the differences thereof removed, so that effects can be obtained that an output suitable for a 3D image in which two images are combined for display is obtained. 
         [0148]    Besides, the engineer can simultaneously control the camera heads  10   a  and  10   b  while correcting the difference between the camera heads  10   a  and  10   b  by use of a correction function and so on. This facilitates the cooperative linkage between the camera heads  10   a  and  10   b.  Thus, handling the two units of the camera heads  10   a  and  10   b  used in the 3D camera systems  1  through  3  facilitates the camera operation (live coverage, relay, and so on) in 3D camera systems. 
         [0149]    The timing generation circuit  22  of the camera adaptor box  12  can provide a match between the imaging timings in accordance with the output timing or an image in which a difference has occurred to adjust the imaging timings of the camera heads  10   a  and  10   b,  thereby simultaneously taking a subject. In addition, the video interface block  24  executes processing such as inverting an image outputted from the camera head  10   b  in match with the imaging timing outputted by the timing generation circuit  22 , thereby matching the outputting timing of the image outputted from the camera adaptor box  12 . Therefore, in matching the images outputted from the camera heads  10   a  and  10   b  as a 3D image, the images having no feeling of unnaturalness can be outputted. 
         [0150]    Further, by use of the images outputted from the camera heads  10   a  and  10   b,  not only the image for each channel, but also a mixed image, a differential image, an anaglyph image, and a divided image can be outputted to the viewfinder block  13  and a display device, not shown. Therefore, effects can be obtained that the adjustment of the irises and setting positions of the camera heads  10   a  and  10   b  are facilitated. 
         [0151]    Variations 
         [0152]    It should be noted that, in the above-described embodiment, iris adjustment values are set for the correction made by use of correction functions, the correction may also be made for zoom setting values and so on by use of correction functions. The values to be correction are not limited to iris and zoom values. 
         [0153]    In the above-described embodiment, an example has been described in which the camera heads  10   a  and  10   b  have no viewfinder block; however, it is also practicable that the two units of cameras each have a viewfinder block. 
         [0154]    The above-mentioned sequence of processing operations may be executed by software as well as hardware as well as a combination of hardware and software. When the above-mentioned sequence of processing operations is executed by software, the operations can be executed by a computer in which the programs constituting the software are installed in dedicated hardware equipment or a computer in which the programs for executing various functions are installed. For example, the programs constituting the desired software may be installed into a general-purpose personal computer or the like for the execution of various functions. 
         [0155]    Further, a recording media storing the program codes of software for realizing the functions of the above-mentioned embodiments may be supplied to the system or apparatuses concerned. It is also practicable to realize the above-mentioned functions by making the computers (or the controllers such as CPUs) of the system or apparatuses read program codes from the recording media for execution. 
         [0156]    The above-mentioned recording media for storing program codes include a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a CD-R, a magnetic tape, a nonvolatile memory card, or a ROM, for example. 
         [0157]    Executing program codes read by the computer realizes the functions of the above-mentioned embodiments. In addition, on the basis of the instructions given by these program codes, the operating system (OS) and so on running on the computer execute part or all of the actual processing. The above-mentioned functions of the above-mentioned embodiments are also realized by this execution processing. 
         [0158]    While preferred embodiments of the present invention have been described using specific terms, such description is for illustrative purpose only, and it is to be understood that changes and variations may be made without departing from the spirit or scope of the following claims. 
         [0159]    The present application contains subject matter related to that disclosed in Japanese Priority Patent Application JP 2009-292607 filed in the Japan Patent Office on Dec. 24, 2009, the entire content of which is hereby incorporated by reference.