Patent Publication Number: US-9894320-B2

Title: Information processing apparatus and image processing system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority under 35 U.S.C. §119 to Japanese Patent Application No. 2015-181145, filed Sep. 14, 2015, the contents of which are incorporated herein by reference in their entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an information processing apparatus and an image processing system. 
     2. Description of the Related Art 
     There are transmission systems for holding a video conference or the like among plural terminal devices via a communication network such as the Internet. In such a transmission system, image data and voice sound data collected by one transmission terminal during the video conference are transmitted to another transmission terminal. The other transmission terminal receives the image data and the voice sound data, displays an image on a display unit or the like, and outputs voice sound from a loudspeaker, such that the video conference can be held between these transmission terminals. 
     RELATED ART DOCUMENTS 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2010-81644 
     SUMMARY OF THE INVENTION 
     In an embodiment, there is provided an information processing apparatus for transmitting image data to an information terminal, the information processing apparatus being capable of performing communication with the information terminal via a network. The information processing apparatus includes a determination unit configured to determine persons from the image data captured by an imaging unit; a speaker estimating unit configured to estimate a speaker among the persons captured in the image data; a measurement unit configured to measure a speech time of the speaker estimated by the speaker estimating unit; an acquisition unit configured to obtain from the image data, based on the speech time measured by the measurement unit, a speaker image including the speaker that continuously speaks for a certain duration; and a transmission unit configured to transmit the speaker image obtained by the acquisition unit to the information terminal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects and further features of embodiments will become apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a diagram illustrating a schematic configuration of a transmission system according to an embodiment of the present invention; 
         FIG. 2A  is a diagram illustrating trimming performed by a transmission terminal  10   aa  and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 2B  is a diagram illustrating trimming performed by a transmission terminal  10   aa  and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 20  is a diagram illustrating trimming performed by a transmission terminal  10   aa  and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 3A  is a diagram illustrating a trimmed image obtained by the transmission terminal  10   aa  by trimming plural speakers at the same time and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 3B  is a diagram illustrating a trimmed image obtained by the transmission terminal  10   aa  by trimming plural speakers at the same time and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 3C  is a diagram illustrating a trimmed image obtained by the transmission terminal  10   aa  by trimming plural speakers at the same time and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 3D  is a diagram illustrating a trimmed image obtained by the transmission terminal  10   aa  by trimming plural speakers at the same time and a screen rendered on a display unit  120   ab  in location II according to an embodiment of the present invention; 
         FIG. 4  is a schematic view of a transmission system according to an embodiment of the present invention; 
         FIG. 5  is a hardware configuration diagram of a transmission terminal according to an embodiment of the present invention; 
         FIG. 6  is a hardware configuration diagram of a transmission managing system according to an embodiment of the present invention; 
         FIG. 7  is a functional block diagram of a transmission managing system and a transmission terminal included in a transmission system according to an embodiment of the present invention; 
         FIG. 8  is a functional block diagram of a trimming unit according to an embodiment of the present invention; 
         FIG. 9  is a sequence diagram depicting a process in a preparation stage for starting communication among plural transmission terminals according to an embodiment of the present invention; 
         FIG. 10  is a sequence diagram depicting a process for establishing a session among plural transmission terminals according to an embodiment of the present invention; 
         FIG. 11A  is a diagram schematically illustrating spherical image data according to an embodiment of the present invention; 
         FIG. 11B  is a diagram schematically illustrating a planar image according to an embodiment of the present invention; 
         FIG. 12  is a diagram schematically illustrating planar image data converted from spherical image data or a part of the spherical image data according to an embodiment of the present invention; 
         FIG. 13  is a diagram illustrating a principle for detecting a sound source direction by a speaker direction estimating unit according to an embodiment of the present invention; 
         FIG. 14  is a diagram illustrating a speaker direction according to an embodiment of the present invention; 
         FIG. 15A  is a diagram illustrating a display mode selecting screen rendered on a display unit of a transmission terminal according to an embodiment of the present invention; 
         FIG. 15B  is a diagram illustrating a screen for selecting options in a single-display mode according to an embodiment of the present invention; 
         FIG. 16A  is a diagram illustrating a screen for selecting options in a plural-display mode according to an embodiment of the present invention; 
         FIG. 16B  is a diagram illustrating a chairperson option screen according to an embodiment of the present invention; 
         FIG. 16C  is a diagram illustrating image data when chairperson setting is selected according to an embodiment of the present invention; 
         FIG. 17  is a diagram illustrating a screen for selecting options in a 360-degree-display mode according to an embodiment of the present invention; 
         FIG. 18  is a flowchart illustrating a flow of an overall operation in a transmission terminal according to an embodiment of the present invention; 
         FIG. 19  is a flowchart illustrating a processing procedure of a transmission terminal in a single-display mode according to an embodiment of the present invention; 
         FIG. 20  is a time chart illustrating screen transition in a single-display mode according to an embodiment of the present invention; 
         FIG. 21  is a flowchart illustrating a processing procedure of a transmission terminal in a plural-display mode according to an embodiment of the present invention; 
         FIG. 22  is a flowchart illustrating a procedure for measuring a speech time by a speech time measuring unit according to an embodiment of the present invention; 
         FIG. 23A  is a diagram schematically illustrating an accumulated speech time of a participant according to an embodiment of the present invention; 
         FIG. 23B  is a diagram schematically illustrating an accumulated speech time of a participant according to an embodiment of the present invention; 
         FIG. 24A  is a diagram illustrating switching of trimmed images according to an embodiment of the present invention; 
         FIG. 24B  is a diagram illustrating switching of trimmed images according to an embodiment of the present invention; 
         FIG. 25A  is a diagram illustrating switching of trimmed images in a zoom-out process according to an embodiment of the present invention; 
         FIG. 25B  is a diagram illustrating switching of trimmed images in a zoom-out process according to an embodiment of the present invention; 
         FIG. 26A  is a diagram illustrating a trimmed image when a 90-degree screen switching option is selected according to an embodiment of the present invention; 
         FIG. 26B  is a diagram illustrating a trimmed image when a 90-degree screen switching option is selected according to an embodiment of the present invention; 
         FIG. 27  is a diagram illustrating a two-screen option according to an embodiment of the present invention; 
         FIG. 28A  is a diagram illustrating a speed-change option according to an embodiment of the present invention; 
         FIG. 28B  is a diagram illustrating trimming intervals relative to an amount of sliding according to an embodiment of the present invention; 
         FIG. 29A  is a diagram illustrating a chairperson option according to an embodiment of the present invention; 
         FIG. 29B  is a diagram illustrating a chairperson option according to an embodiment of the present invention; 
         FIG. 29C  is a diagram illustrating a chairperson option according to an embodiment of the present invention; 
         FIG. 30  is a diagram illustrating image data displayed in a 360-degree-display mode according to an embodiment of the present invention; 
         FIG. 31A  is a diagram illustrating a fixed participant option according to an embodiment of the present invention; 
         FIG. 31B  is a diagram illustrating a fixed participant option according to an embodiment of the present invention; 
         FIG. 32A  is a diagram illustrating a speaker emphasis option according to an embodiment of the present invention; 
         FIG. 32B  is a diagram illustrating a speaker emphasis option according to an embodiment of the present invention; 
         FIG. 33  is a flowchart illustrating an operation procedure of a trimming unit in a single-display mode according to an embodiment of the present invention; 
         FIG. 34  is a flowchart illustrating an operation procedure of a trimming unit in a single-display mode according to an embodiment of the present invention; 
         FIG. 35A  is a flowchart illustrating an operation procedure of a trimming unit in a plural-display mode according to an embodiment of the present invention; 
         FIG. 35B  is a diagram illustrating zooming out in a predetermined direction in a plural-display mode according to an embodiment of the present invention; 
         FIG. 35C  is a diagram illustrating zooming out in a predetermined direction in a plural-display mode according to an embodiment of the present invention; 
         FIG. 35D  is a diagram illustrating zooming out in a direction opposite to a predetermined direction in a plural-display mode according to an embodiment of the present invention; 
         FIG. 35E  is a diagram illustrating zooming out in a direction opposite to a predetermined direction in a plural-display mode according to an embodiment of the present invention; 
         FIG. 36A  is a flowchart illustrating a procedure for determining a field of view in the latitudinal direction in a plural-display mode according to an embodiment of the present invention; 
         FIG. 36B  is a diagram illustrating a center line in a plural-display mode according to an embodiment of the present invention; and 
         FIG. 36C  is a diagram illustrating a trimmed image in a plural-display mode according to an embodiment of the present invention. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     In the following, embodiments of the present invention will be described with reference to the accompanying drawings. 
     It is an object of at least one embodiment of the present invention to provide an information processing apparatus by which frequent changes of a screen is reduced. 
       FIG. 1  is a diagram illustrating a schematic configuration of a transmission system  1  according to an embodiment of the present invention. In  FIG. 1 , a video conference is held between two locations of location I and location II. Six participants A to F are seated around a table in location I and one participant “a” is present in location II. 
     On the table of location I, a spherical camera  112   a  capable of capturing an image of 360-degree surroundings and a microphone  114  are disposed. The spherical camera  112   a  and the microphone  114  are connected to a transmission terminal  10   aa . Further, a display unit  120   aa  is connected to the transmission terminal  10   aa . In location II, a transmission terminal  10   ab  including a built-in camera and a built-in microphone is disposed and a display unit  120   ab  is connected to the transmission terminal  10   ab.    
     Based on such a configuration, the transmission terminal  10   aa  processes image data as described below, the image data being captured by the spherical camera  112   a , and transmits the processed image data to location II. Further, the transmission terminal  10   ab  transmits image data captured by the built-in camera to location I. Accordingly, the display unit  120   aa  displays the image data including the participant “a” and the display unit  120   ab  displays the image data including one or more participants A to F (all of six persons in  FIG. 1 ). 
     The spherical camera  112   a  captures images of the participants A to F in this manner, so that the participant “a” can view all of the participants A to F in location I and the video conference can be realized with presence. 
     The transmission terminal  10   aa  in this embodiment trims, based on a result of detection of a speaker from the participants A to F, a part of the image data captured by the spherical camera  112   a  and transmits the trimmed image data (hereafter a “trimmed image”) to location II. 
     The trimming performed by the transmission terminal  10   aa  is described with reference to  FIGS. 2A to 2C .  FIGS. 2A to 2C  are diagrams illustrating the trimming performed by the transmission terminal  10   aa  and a screen rendered on the display unit  120   ab  in location II according to the embodiment of the present invention. 
       FIG. 2A  illustrates a trimmed image displayed on the display unit  120   ab  and a process performed by the transmission terminal  10   aa . Because the participant B is making a speech, the transmission terminal  10   aa  trims, from the image data, an area where an image of the participant B is captured. Accordingly, the display unit  120   ab  displays a trimmed image  9  in which the participant B is included. 
       FIG. 2B  illustrates a trimmed image displayed on the display unit  120   ab  when the participant E starts a speech and a process performed by the transmission terminal  10   aa . The transmission terminal  10   aa  detects that the participant E starts the speech. However, the transmission terminal  10   aa  according to the embodiment does not change the trimmed image  9  until a switching time has elapsed. Accordingly, the display unit  120   ab  continuously displays the trimmed image  9  in which the participant B is included. 
       FIG. 2C  illustrates a trimmed image displayed on the display unit  120   ab  when the switching time has elapsed since the participant E started the speech and a process performed by the transmission terminal  10   aa . The transmission terminal  10   aa  detects that the participant E has been continuously speaking for the switching time or more. The transmission terminal  10   aa  trims, from the image data, an area where an image of the participant E is captured. Accordingly, the display unit  120   ab  displays the trimmed image  9  in which the participant E is included. 
     In this manner, because the trimmed images  9  are switched if a speaker continuously speaks for the switching time or more, it is possible to reduce frequent changes of a screen of the display unit  120   ab . In other words, if the trimmed images  9  are to be switched, at least the switching time has to elapse. Accordingly, the frequency of obtaining the trimmed images  9  or the frequency of switching the trimmed images  9  (update frequency) is limited to a predetermined number or less, so that it is possible to reduce the frequent changes of the screen of the display unit  120   ab.    
     The following describes a trimmed image  9  in a case where the transmission terminal  10   aa  trims plural speakers at the same time. 
       FIGS. 3A to 3D  are diagrams illustrating the trimmed image  9  obtained by the transmission terminal  10   aa  by trimming the plural speakers at the same time and a screen rendered on the display unit  120   ab  in location II according to the embodiment of the present invention. In  FIGS. 3A to 3D , it is assumed that two persons (users of the transmission terminal  10   aa ) are selected as the speakers. 
     In  FIG. 3A , a speech time of the participants C and D is longer than other participants, so that the transmission terminal  10   aa  trims, from image data, an area where an image of the participants C and D is captured. Accordingly, the display unit  120   ab  displays the trimmed image  9  in which the participants C and D are included. 
     As illustrated in  FIG. 3B , the transmission terminal  10   aa  counts a speech time of each participant at certain time intervals. This certain period of time (predetermined period of time) is referred to as a counting time. In other words, the transmission terminal  10   aa  specifies two persons in descending order of speech time during the counting time. The trimmed images  9  are not switched during the counting time. 
       FIG. 3C  is a diagram illustrating the trimmed image  9  when the counting time has elapsed and a screen rendered on the display unit  120   ab  in location II. It is assumed that top two persons having a longer speech time during the counting time are the participants E and F. In this case, the transmission terminal  10   aa  trims, from image data, an area where an image of the participants E and F is captured. Accordingly, the display unit  120   ab  displays the trimmed image  9  in which the participants E and F are included. 
     In this manner, it is possible to reduce frequent changes of the screen of the display unit  120   ab  by switching the trimmed images  9  based on counting time because the trimmed images  9  are not switched after the counting time has elapsed. 
     Further, it is assumed that top two persons having a longer speech time during the counting time are the participants A and D. This case is described with reference to  FIG. 3D . The transmission terminal  10   aa  trims, from image data, an area where an image of the participants A to D is captured. Accordingly, the display unit  120   ab  displays the trimmed image  9  in which the participants A, B, C, and D are included. In this manner, even if the intended speakers are not arranged side by side, it is possible to trim and display the top two persons having a longer speech time. 
     &lt;System Configuration&gt; 
       FIG. 4  is a schematic view of the transmission system  1  according to the embodiment of the present invention. The transmission system  1  (an example of a communication system) is a communication system for mutually communicating information and feelings among a plurality of transmission terminals via a transmission managing system  50 . Examples of the transmission system  1  include a video conference system, a videophone system, a voice conference system, a voice phone system, a Personal Computer (PC) screen sharing system, a text chat system, and the like. Further, the transmission system  1  includes a data providing system that transmits content data in one direction from one transmission terminal to another transmission terminal via the transmission managing system  50 . 
     In the embodiment, a system capable of holding a video conference is assumed and described as an example of the communication system. 
     The transmission system  1  illustrated in  FIG. 4  includes a plurality of transmission terminals ( 10   aa ,  10   ab , . . . ), a plurality of mobile terminals ( 20   aa ,  20   ab , . . . ), display units ( 120   aa ,  120   ab , . . . ) for the transmission terminals ( 10   aa ,  10   ab , . . . ), a plurality of the relay devices ( 30   a ,  30   b , . . . ), the transmission managing system  50 , and a program providing system  90 . 
     The transmission terminals  10  transmit and receive image data and voice sound data as an example of content data. In other words, the transmission terminals  10  may be video conference terminals capable of using video conference service. In this embodiment, the transmission terminal  10  is assumed to be a terminal dedicated to a video conference. 
     The mobile terminals  20  transmit and receive image data and voice sound data as an example of content data. The mobile terminals  20  may be able to transmit or receive text data. In other words, the mobile terminals  20  may use not only the video conference but also a text chat. In this embodiment, the mobile terminal  20  may be a tablet terminal, a mobile phone, a smartphone, a Personal Digital Assistant (PDA), a wearable PC, a game console, a general-purpose PC terminal, a car navigation terminal, an electronic whiteboard, a projector, a monitoring camera, industrial equipment having a communication function, or the like unless otherwise specified. Further, the industrial equipment includes office equipment such as a Multifunction Peripheral/Printer/Product (MFP), medical equipment such as an endoscope, and agricultural equipment such as a cultivator. The wearable PC includes a wristwatch, a head-mounted display, and the like. In addition, the mobile terminal  20  is wirelessly connected to a communication network  2  via a mobile communication network or Wireless Fidelity (WiFi), for example. 
     As will be clear from the following hardware configuration, the transmission terminal  10  and the mobile terminal  20  are each referred to as information processing apparatuses. 
     The transmission terminal  10  and the mobile terminal  20  are managed by the transmission managing system  50  that manages call control of the transmission system  1 . 
     In the following, a given transmission terminal among the plurality of transmission terminals ( 10   aa ,  10   ab , . . . ) is described as a “transmission terminal  10 ” and a given mobile terminal among the plurality of mobile terminals  20  ( 20   aa ,  20   ab , . . . ) is described as a “mobile terminal  20 .” The same applies to the display unit  120 , the relay device  30 , and a router  70 . 
     Further, a terminal that sends a request to start a video conference from one transmission terminal  10  or mobile terminal  20  to another transmission terminal  10  or mobile terminal  20  may be described as a “requestor terminal” and a terminal to which the request is sent as a destination may be described as a “destination terminal.” 
     Further, in the transmission system  1 , a session for management information to transmit or receive various types of management information via the transmission managing system  50  is established between the requestor terminal and the destination terminal. Further, a session to transmit or receive content data via the relay device  30  is established between the requestor terminal and the destination terminal. In addition, in the session to transmit or receive the content data, it is not always necessary to communicate via the relay device  30  but communication may be performed via the transmission managing system  50 . Further, the requestor terminal and the destination terminal may communicate with each other directly. 
     The relay device  30  relays content data among the transmission terminals  10  and the mobile terminals  20  as described above. 
     The transmission managing system  50  performs call control between the transmission terminals  10  or the mobile terminals  20 . The transmission managing system  50  also performs log-in authentication of the transmission terminal  10  and the mobile terminal  20 , manages a call status, manages a destination list, reports a destination of content data to the relay device  30 , and causes the relay device  30  to manage the call status, for example. 
     While the transmission managing system  50  is an information processing apparatus, the transmission managing system  50  may also be a monitoring camera, industrial equipment having a communication function, a wearable PC, or the like. Further, the industrial equipment includes office equipment such as an MFP, medical equipment such as an endoscope, and agricultural equipment such as a cultivator. The wearable PC includes a wristwatch, a head-mounted display, and the like. 
     The program providing system  90  stores a terminal program in a Hard Disk (HD)  304  described later, the terminal program causing the transmission terminal  10  or the mobile terminal  20  to implement various types of functions. The program providing system  90  can transmit the terminal program to the transmission terminal  10  and the mobile terminal  20 . The program providing system  90  also stores a management apparatus program in the HD  304 , the management apparatus program causing the transmission managing system  50  to implement various types of functions. The program providing system  90  can transmit the management apparatus program to the transmission managing system  50 . 
     The transmission terminals ( 10   aa ,  10   ab ,  10   ac , . . . ), the relay device  30   a , and a router  70   a  are communicatively connected via a LAN  2   a . The transmission terminals ( 10   ad ,  10   bb ,  10   bc , . . . ), the mobile terminals ( 20   aa ,  20   ab , . . . ), the relay device  30   b , and a router  70   b  are communicatively connected via a LAN  2   b . The LAN  2   a  and the LAN  2   b  are communicatively connected via a dedicated line tab in which a router  70   ab  is included. The LAN  2   a  and the LAN  2   b  are constructed within a predetermined region A. For example, the region A is Japan, the LAN  2   a  is constructed within an office in Tokyo and the LAN  2   b  is constructed within an office in Osaka. Further, the mobile terminals ( 20   aa ,  20   ab , . . . ) are used in the region A. 
     Further, transmission terminals ( 10   ca ,  10   cb ,  10   cc , . . . ), a relay device  30   c , and a router  70   c  are communicatively connected via a LAN  2   c . Transmission terminals ( 10   da ,  10   db ,  10   dc , . . . ), mobile terminals ( 20   ac ,  20   ad , . . . ), a relay device  30   d , and a router  70   d  are communicatively connected via a LAN  2   d . The LAN  2   c  and the LAN  2   d  are communicatively connected via a dedicated line  2   cd  in which a router  70   cd  is included. The LAN  2   c  and the LAN  2   d  are constructed within a predetermined region B. For example, the region B is the United States of America, the LAN  2   c  is constructed within an office in New York and the LAN  2   d  is constructed within an office in Washington D.C. Further, mobile terminals ( 20   ac ,  20   ad , . . . ) are used in the region B. 
     The transmission managing system  50  and the program providing system  90  are communicatively connected to the transmission terminal  10 , the mobile terminal  20 , and the relay device  30  via the Internet  2   i . The transmission managing system  50  and the program providing system  90  may be disposed in the region A, the region B, or another region. 
     Further, in  FIG. 4 , a set of four numbers beneath each transmission terminal  10 , each mobile terminal  20 , each relay device  30 , the transmission managing system  50 , each router  70 , and the program providing system  90  indicates an IP address in IPv4 in a simplified manner. 
     &lt;Hardware Configuration&gt; 
     &lt;&lt;Transmission Terminal&gt;&gt; 
     In the following, a hardware configuration of the transmission terminal  10  is described with reference to  FIG. 5 .  FIG. 5  is a hardware configuration diagram of the transmission terminal  10  according to the embodiment. As illustrated in  FIG. 5 , the transmission terminal  10  according to the embodiment includes a Central Processing Unit (CPU)  101  that controls the entire operation of the transmission terminal  10 . Further, the transmission terminal  10  includes a Read Only Memory (ROM)  102  that stores a program such as an Initial Program Loader (IPL) used to drive the CPU  101  and includes a Random Access Memory (RAM)  103  used as a work area of the CPU  101 . The transmission terminal  10  also includes a flash memory  104  that stores various types of data such as a terminal program  1010 , image data, and voice sound data. The transmission terminal  10  also includes a Solid State Drive (SSD)  105  that controls reading or writing of various types of data from or into the flash memory  104  in accordance with control of the CPU  101 . Further, the transmission terminal  10  also includes a media drive  107  that controls reading or writing (storage) of data from or into a recording medium  106  such as a flash memory, and an operation button  108  to be operated to select a destination of the transmission terminal  10 . The transmission terminal  10  also includes a power supply switch  109  for switching ON/OFF a power supply for the transmission terminal  10 , a SIM slot  121  into which a SIM card is detachably inserted, and a network Interface (I/F)  111  for transmitting data via the communication network  2 . 
     The transmission terminal  10  also includes a built-in camera  112  that captures an image of a photographic subject in accordance with control of the CPU  101  and obtains image data, an imaging device I/F  113  that controls driving of the camera  112 , and a built-in microphone  114  that inputs voice sound. The camera  112  may be a spherical camera capable of capturing an image of 360-degree surroundings (360 degrees in the longitudinal direction and in the latitudinal direction). However, it is not necessary to be able to capture an image of all of 360-degree surroundings but may be able to capture an image in a 360-degree range only in the longitudinal direction. Further, the camera  112  may also be able to capture a wide angle image only in a 180-degree range in the longitudinal direction. A lower limit of an imaging range may be determined with a wide field of view capable of capturing an image of plural participants at a time. 
     The microphone  114  is preferably a directional microphone. Further, the transmission terminal  10  also includes a built-in loudspeaker  115  that outputs voice sound and a voice sound input/output I/F  116  that processes input and output of a voice sound signal between the microphone  114  and the loudspeaker  115  in accordance with control of the CPU  101 . The transmission terminal  10  also includes a display I/F  117  that transmits image data to an external display unit  120  in accordance with control of the CPU  101  and an external device connection I/F  118  for connecting various types of external devices. Further, the transmission terminal  10  includes an authentication receiving I/F  119  and a bus line  110  such as an address bus or a data bus for electrically connecting each of the above constituent elements as illustrated in  FIG. 5 . 
     The display unit  120  may be a display device configured with liquid crystal or organic EL to display an image of a photographic subject, icons for operation, or the like. Further, the display unit  120  is connected to the display I/F  117  via a cable  120   c . Although the display unit  120  of the transmission terminal  10  is connected to the display I/F  117  via the cable  120   c , the display unit  120  is not limited to this and the display unit  120  may be built in the transmission terminal  10 . 
     An external device such as an external camera, an external microphone, and an external loudspeaker may be connected to the external device connection I/F  118  via a Universal Serial Bus (USB) cable, for example. The external camera may be the spherical camera  112   a  and the external microphone may be a directional microphone. If the spherical camera  112   a  is an external device, the transmission terminal  10  and the spherical camera  112   a  operate as an image processing system. 
     The authentication receiving I/F  119  is an interface for receiving input of authentication information from a user. Specifically, the authentication receiving I/F  119  corresponds to an IC card reader (Near Field Communication (NFC), for example) or a reader for SD cards, SIM cards, or the like. 
     Further, the terminal program  1010  may be recorded and distributed in a computer-readable recording medium such as the recording medium  106  with a file in an installable format or an executable format. Further, the terminal program  1010  may be stored in the ROM  102  instead of the flash memory  104 . 
     A hardware configuration of the mobile terminal  20  has many corresponding portions with respect to the hardware configuration of the transmission terminal  10 . Even if there is a difference, it is assumed that the difference is not a hindrance to construction of the transmission system  1 . 
     &lt;&lt;Transmission Managing System, Relay Device, Program Providing System&gt;&gt; 
     In the following, a hardware configuration of the transmission managing system  50  is described with reference to  FIG. 6 .  FIG. 6  is a hardware configuration diagram of the transmission managing system  50  according to the embodiment. 
     In addition, the hardware configuration of the transmission managing system  50  and the like illustrated in the drawing does not need to be prepared as an integrated device housed in a single case. The hardware configuration indicates hardware elements preferably included in the transmission managing system  50  and the like. Further, in order to support cloud computing, the physical configuration of the transmission managing system  50  and the like of the embodiment may not be fixed but the physical configuration may be determined by dynamically coupling or disconnecting hardware resources depending on load. 
     The transmission managing system  50  includes a CPU  301  that controls the entire operation of the transmission managing system  50 , a ROM  302  that stores a program such as an IPL used to drive the CPU  301 , and a RAM  303  used as a work area of the CPU  301 . Further, the transmission managing system  50  also includes the HD  304  that stores various types of data such as the management apparatus program and a Hard Disk Drive (HDD)  305  that controls reading or writing of various types of data from or into the HD  304  in accordance with control of the CPU  301 . Further, the transmission managing system  50  also includes a media drive  307  that controls reading or writing (storage) of data from or into a recording medium  306  such as a flash memory and a display unit  308  that displays various types of information such as a cursor, a menu, a window, characters, or an image. Further, the transmission managing system  50  also includes a network I/F  309  for transmitting data via the communication network  2 , a keyboard  311  having a plurality of keys for inputting characters, numerical values, and various types of instructions, and a mouse  312  for selecting and executing various types of instructions, selecting an object to be processed, and moving the cursor. Further, the transmission managing system  50  also includes a CD-ROM drive  314  that controls reading of various types of data from a Compact Disc Read Only Memory (CD-ROM)  313  as an example of a removable recording medium. The transmission managing system  50  also includes a bus line  310  such as an address bus or a data bus for electrically connecting each of the above constituent elements as illustrated in  FIG. 6 . 
     In addition, the management apparatus program may be recorded and distributed in a computer-readable recording medium such as the recording medium  306  or the CD-ROM  313  with a file in an installable format or an executable format. Further, the management apparatus program may be stored in the ROM  302  instead of the HD  304 . 
     Because the relay device  30  and the program providing system  90  have the same hardware configuration as in the transmission managing system  50 , a description of the hardware configuration is omitted. 
     &lt;Functional Configuration of Transmission System&gt; 
     In the following, a functional configuration of the transmission system  1  according to the embodiment is described with reference to  FIG. 7 .  FIG. 7  is a functional block diagram of the transmission managing system  50  and the transmission terminal  10  included in the transmission system  1  according to the embodiment of the present invention. In  FIG. 7 , the transmission terminal  10  and the transmission managing system  50  are connected to be able to perform data communication via the communication network  2 . Further, the relay device  30  and the program providing system  90  illustrated in  FIG. 4  are omitted from  FIG. 7  because these elements are not directly related to trimming. 
     &lt;&lt;Functional Configuration of Transmission Terminal&gt;&gt; 
     The transmission terminal  10  includes a transmission and reception unit  11 , a log-in requesting unit  12 , a voice sound input unit  13 , a speaker direction estimating unit  14 , a voice sound output unit  15 , an operation input receiving unit  16 , an imaging unit  17 , a trimming unit  18 , a display controlling unit  19 , a destination list creating unit  21 , and a storing and reading processing unit  29 . These units are functions to be realized or units to be provided when any one of the constituent elements illustrated in  FIG. 5  operates in response to an instruction from the CPU  101  compliant with the terminal program  1010  loaded in the RAM  103  from the flash memory  104 . 
     Further, the transmission terminal  10  also includes a storage unit  1000  constructed with the RAM  103 , the ROM  102 , and the flash memory  104  illustrated in  FIG. 5 . The storage unit  1000  stores the terminal program  1010 . 
     (Functional Configuration of Transmission Terminal) 
     In the following, the functional configuration of the transmission terminal  10  is described in detail with reference to  FIGS. 5 and 7 . The transmission and reception unit  11  of the transmission terminal  10  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the network I/F  111  illustrated in  FIG. 5 , and the like. The transmission and reception unit  11  transmits and receives various types of data to and from the relay device  30  and the transmission managing system  50  via the communication network  2 . The transmission and reception unit  11  starts receiving state information that indicates a state of each transmission terminal  10  as a destination candidate from the transmission managing system  50  before starting communication with a desired destination terminal. In addition, this state information indicates not only an operation state (online or offline state) of each transmission terminal  10  but also a detailed state indicating whether the transmission terminal  10  is in communication in the online state, whether a user is away in the online state, and the like. 
     The log-in requesting unit  12  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5  and the like. The log-in requesting unit  12  automatically transmits, upon reception of a power-on, log-in request information indicating a log-in request and an IP address of a requestor terminal at this moment from the transmission and reception unit  11  to the transmission managing system  50  via the communication network  2 . Further, if the user turns the power supply switch  109  from ON to OFF, after the transmission and reception unit  11  transmits state information about powering OFF to the transmission managing system  50 , the operation input receiving unit  16  completely powers the transmission terminal  10  OFF. In accordance with this, the transmission managing system  50  is able to determine that the transmission terminal  10  is powered OFF. 
     The voice sound input unit  13  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the voice sound input/output I/F  116  illustrated in  FIG. 5 , and the like. After voice sound of the user is converted into a voice sound signal by the microphone  114 , the voice sound input unit  13  inputs voice sound data related to this voice sound signal. 
     The speaker direction estimating unit  14  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the voice sound input/output I/F  116  illustrated in  FIG. 5 , and the like. The speaker direction estimating unit  14  detects a direction of a speaker. This will be described in detail with reference to  FIG. 13 . 
     The voice sound output unit  15  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the voice sound input/output I/F  116  illustrated in  FIG. 5 , and the like. The voice sound output unit  15  outputs a voice sound signal related to voice sound data to the loudspeaker  115  and causes the loudspeaker  115  to output voice sound. 
     The operation input receiving unit  16  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the operation button  108 , the power supply switch  109  illustrated in  FIG. 5 , and the like. The operation input receiving unit  16  receives various types of inputs performed by the user. For example, if the user switches the power supply switch  109  ON, the power supply switch  109  being illustrated in  FIG. 5 , the operation input receiving unit  16  illustrated in  FIG. 7  receives a power-on to switch the transmission terminal  10  ON. 
     The imaging unit  17  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the camera  112 , the imaging device I/F  113  illustrated in  FIG. 5 , and the like. The imaging unit  17  captures an image of a photographic subject and outputs image data obtained by the capturing. 
     The trimming unit  18  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5  and the like. The trimming unit  18  trims a part from image data about 360-degree surroundings captured by the imaging unit  17 . The trimming unit  18  will be described in detail with reference to  FIG. 8 . 
     The display controlling unit  19  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5 , the display I/F  117  illustrated in  FIG. 5 , and the like. The display controlling unit  19  performs control to generate a screen displayed during a conference and to transmit this screen to the display unit  120 . 
     The destination list creating unit  21  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5  and the like. The destination list creating unit  21  creates and updates a destination list based on state information about the transmission terminal  10  received as a destination candidate from the transmission managing system  50 , the destination list having an icon that indicates a state of the transmission terminal  10  as the destination candidate. 
     The storing and reading processing unit  29  is implemented by an instruction from the CPU  101  illustrated in  FIG. 5  and the SSD  105  illustrated in  FIG. 5 . The storing and reading processing unit  29  performs a process to store various types of data in the storage unit  1000  or read various types of data stored in the storage unit  1000 . Other than an item illustrated in the drawings, in the storage unit  1000 , image data, voice sound data, and display data received upon performing a call to a destination terminal are overwritten in each reception. 
     &lt;&lt;Functional Configuration of Transmission Managing System&gt;&gt; 
     The transmission managing system  50  includes a transmission and reception unit  51 , a terminal authentication unit  52 , a state management unit  53 , a terminal state obtaining unit  54 , a session management unit  55 , a terminal extraction unit  56 , and a storing and reading processing unit  59 . These units are functions to be realized or units to be provided when any one of the constituent elements illustrated in  FIG. 6  operates in response to an instruction from the CPU  301  compliant with a management apparatus program  5010  loaded in the RAM  303  from the HO  304 . 
     Further, the transmission managing system  50  includes a storage unit  5000  configured with the HDD  305 , the RAM  303 , the ROM  302 , and the like illustrated in  FIG. 6 . In the following, various types of databases included in the storage unit  5000  are described. 
     
       
         
           
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Relay device managing table 
               
            
           
           
               
               
               
               
               
            
               
                   
                   
                   
                 IP 
                   
               
               
                 Relay 
                   
                   
                 address 
                 Maximum data 
               
               
                 device 
                 Operation 
                 Reception date 
                 of relay 
                 transmission 
               
               
                 ID 
                 state 
                 and time 
                 device 
                 rate (Mbps) 
               
               
                   
               
            
           
           
               
               
               
               
               
            
               
                 111a 
                 Online 
                 2013.11.10.13:00 
                 1.2.1.2 
                 100 
               
               
                 111b 
                 Online 
                 2013.11.10.13:10 
                 1.2.2.2 
                 1000 
               
               
                 111c 
                 Offline 
                 2013.11.10.13:20 
                 1.3.1.2 
                 100 
               
               
                 111d 
                 Online 
                 2013.11.10.13:30 
                 1.3.2.2 
                 10 
               
               
                   
               
            
           
         
       
     
     In the storage unit  5000 , a relay device managing database (DB)  5001  configured with a relay device managing table is constructed. In the relay device managing table, an operation state of each relay device  30 , a reception date and time when state information indicating the operation state is received by the transmission managing system  50 , an IP address of the relay device  30 , and a maximum data transmission rate (Mbps) in the relay device  30  are managed in association with a relay device ID of each relay device  30 . 
     
       
         
           
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Terminal authentication managing table 
               
            
           
           
               
               
               
            
               
                   
                 Communication ID 
                 Password 
               
               
                   
                   
               
               
                   
                 01aa 
                 aaaa 
               
               
                   
                 01ab 
                 abab 
               
               
                   
                 01ac 
                 acac 
               
               
                   
                 . . . 
                 . . . 
               
               
                   
                   
               
            
           
         
       
     
     Further, in the storage unit  5000 , a terminal authentication managing DB  5002  configured with a terminal authentication managing table is constructed. In the terminal authentication managing table, a password is managed in association with a communication ID of each transmission terminal  10  managed by the transmission managing system  50 . 
     
       
         
           
               
             
               
                 TABLE 3 
               
             
            
               
                   
               
               
                 Terminal managing table 
               
            
           
           
               
               
               
               
               
            
               
                 Communication 
                   
                 Operation 
                 Reception date 
                 IP 
               
               
                 ID 
                 Name 
                 state 
                 and time 
                 address 
               
               
                   
               
               
                 01aa 
                 Conference 
                 Online 
                 2013.11.10.13:40 
                 1.2.1.3 
               
               
                   
                 terminal AA 
               
               
                 01ab 
                 Conference 
                 Online 
                 2013.11.09.12:00 
                 1.2.1.4 
               
               
                   
                 terminal AB 
               
               
                 01ac 
                 Conference 
                 Online 
                 2013.11.11.13:00 
                 1.2.1.5 
               
               
                   
                 terminal AC 
               
               
                 01ad 
                 Conference 
                 Online 
                 2013.11.10.13:45 
                 1.2.2.3 
               
               
                   
                 terminal AD 
               
               
                 01bb 
                 Conference 
                 Offline 
                 2013.11.10.13:50 
                 1.2.2.4 
               
               
                   
                 terminal BB 
               
               
                   
               
            
           
         
       
     
     Further, in the storage unit  5000 , a terminal managing DB  5003  configured with a terminal managing table is constructed. In the terminal managing table, a name (destination name) when the transmission terminal  10  is a destination, an operation state of the transmission terminal  10 , a reception date and time when log-in request information described below is received by the transmission managing system  50 , and an IP address of the transmission terminal  10  are managed in association with the communication ID of each transmission terminal  10 . 
     
       
         
           
               
             
               
                 TABLE 4 
               
             
            
               
                   
               
               
                 Destination list managing table 
               
            
           
           
               
               
               
            
               
                   
                 Communication ID 
                 Destination list 
               
               
                   
                   
               
               
                   
                 01aa 
                 01ab, 01ac, 01ad, 01bb 
               
               
                   
                 01ab 
                 01aa, 01ac, 01ad, 01bb 
               
               
                   
                 01ac 
                 01aa, 01ab, 01ad, 01bb 
               
               
                   
                 01ad 
                 01aa, 01ab, 01ac, 01bb 
               
               
                   
                 01bb 
                 01aa, 01ab, 01ac, 01ad 
               
               
                   
                 . . . 
                 . . . 
               
               
                   
                   
               
            
           
         
       
     
     Further, in the storage unit  5000 , a destination list managing DB  5004  configured with a destination list managing table is constructed. In the destination list managing table, all of communication IDs of transmission terminals registered as candidates for a destination terminal are managed in association with a communication ID of a requestor terminal that sends a request to start a call in a video conference. For example, in the destination list managing table indicated in Table 4, candidates for a destination terminal to which a requestor terminal (transmission terminal  10   aa ) having the communication ID “ 01   aa ” can send a request to start a call in a video conference include the transmission terminal  10   ab  having the communication ID “ 01   ab ,” the transmission terminal  10   ac  having the communication ID “ 01   ac ,” the transmission terminal  10   ad  having the communication ID “ 01   ad ,” and the transmission terminal  10   bb  having the communication ID “ 01   bb .” 
     
       
         
           
               
             
               
                 TABLE 5 
               
             
            
               
                   
               
               
                 Session managing table 
               
            
           
           
               
               
               
               
               
            
               
                   
                 Relay 
                 Requestor 
                 Destination 
                   
               
               
                 Session 
                 device 
                 communication 
                 communication 
                 Conference 
               
               
                 ID 
                 ID 
                 ID 
                 ID 
                 ID 
               
               
                   
               
               
                 se1 
                 111a 
                 01aa 
                 01ac 
                 C01 
               
               
                 se2 
                 111b 
                 01aa 
                 01ab 
                 C01 
               
               
                 se3 
                 111d 
                 01aa 
                 01ad 
                 C01 
               
               
                 . . . 
                 . . . 
                 . . . 
                 . . . 
                 . . . 
               
               
                   
               
            
           
         
       
     
     Further, in the storage unit  5000 , a session managing DB  5005  configured with a session managing table is constructed. In the session managing table, a relay device ID of the relay device  30  used to relay image data and voice sound data, a communication ID of a requestor terminal, a communication ID of a destination terminal, and a conference ID are managed in association with a session ID used to perform a session to select the relay device  30 . The session ID is an ID to identify a session and transmission terminals  10  participating in the same conference are not necessarily included in the same session. By contrast, the same conference ID is assigned to transmission terminals  10  that participate in the same conference. 
     (Functional Configuration of Transmission Managing System) 
     In the following, the functional configuration of the transmission managing system  50  is described in detail. The transmission and reception unit  51  is implemented by an instruction from the CPU  301 , the network I/F  309 , and the like illustrated in  FIG. 6 . The transmission and reception unit  51  transmits or receives various types of data to or from the transmission terminal  10  or the relay device  30  via the communication network  2 . 
     The terminal authentication unit  52  is implemented by an instruction from the CPU  301  and the like illustrated in  FIG. 6 . The terminal authentication unit  52  authenticates the transmission terminal  10  while using a communication ID and a password as a search key, the communication ID and the password being included in log-in request information received via the transmission and reception unit  51 . In other words, the terminal authentication unit  52  performs terminal authentication by searching the terminal authentication managing DB  5002  and determining whether the same communication ID and the password are managed in the terminal authentication managing DB  5002 . In addition, the authentication method is not limited to this but a client certificate (an authentication method in which a public key and a private key are used) may be used. 
     The state management unit  53  is implemented by an instruction from the CPU  301  and the like illustrated in  FIG. 6 . In order to manage an operation state of a requestor terminal that sends a log-in request, the state management unit  53  stores and manages a communication ID of the requestor terminal, the operation state of the requestor terminal, a reception date and time when log-in request information is received by the transmission managing system  50 , and an IP address of the requestor terminal in an associated manner in the terminal managing DB  5003 . 
     Further, the state management unit  53  is implemented by an instruction from the CPU  301  and the like illustrated in  FIG. 6 . When a user switches the power supply switch  109  of the transmission terminal  10  from ON to OFF, the state management unit  53  changes an operation state from online to offline in the terminal managing DB  5003  based on state information about powering OFF transmitted from the transmission terminal  10 . 
     The terminal extraction unit  56  is implemented by an instruction from the CPU  301  illustrated in  FIG. 6 . The terminal extraction unit  56  searches the destination list managing DB  5004  while using, as a search key, the communication ID of the requestor terminal that sent a log-in request and extracts communication IDs of candidates for a destination terminal that can call the requestor terminal. Further, the terminal extraction unit  56  also searches the destination list managing DB  5004  while using, as a search key, the communication ID of the requestor terminal that sent the log-in request and extracts communication IDs of other requestor terminals that register the communication ID of the requestor terminal as a candidate for a destination terminal. 
     The terminal state obtaining unit  54  is implemented by an instruction from the CPU  301  illustrated in  FIG. 6 . The terminal state obtaining unit  54  searches the terminal managing DB  5003  while using, as a search key, the communication IDs of the candidates for a destination terminal extracted by the terminal extraction unit  56  and reads an operation state in each communication ID extracted by the terminal extraction unit  56 . In accordance with this, the terminal state obtaining unit  54  can obtain the operation state of the candidates for a destination terminal that can call the requestor terminal which sends the log-in request. 
     The session management unit  55  is implemented by an instruction from the CPU  301  illustrated in  FIG. 6 . The session management unit  55  stores and manages a session ID, the communication ID of the requestor terminal, the communication ID of the destination terminal, and a conference ID in an associated manner in the session managing DB  5005 . 
     The storing and reading processing unit  59  is implemented by an instruction from the CPU  301 , the HDD  305 , and the like illustrated in  FIG. 6 . The storing and reading processing unit  59  performs a process to store various types of data in the storage unit  5000  or read various types of data stored in the storage unit  5000 . 
     &lt;Trimming Unit&gt; 
       FIG. 8  is a functional block diagram of the trimming unit  18  according to the embodiment of the present invention. The trimming unit  18  includes a participant detecting unit  61 , a speech time measuring unit  62 , a cutting portion determining unit  63 , and a screen switching unit  64 . 
     The participant detecting unit  61  analyzes image data to detect a participant. In other words, the participant detecting unit  61  performs image processing such as facial recognition on the image data and, if an image of a person is captured, specifies a location where the image is present. This location is expressed in coordinates or latitude and longitude of pixels that define the geometric center of the face, for example. 
     The speech time measuring unit  62  measures a speech time for each participant. For example, the speech time measuring unit  62  measures a time of a continuous speech as a speech time or measures a time of a speech in a certain period. Specifically, the speech time measuring unit  62  obtains a direction of a speaker from the speaker direction estimating unit  14  and specifies a speaker in comparison with a location of the participant. Then the speech time measuring unit  62  measures a speech time of the speaker. In addition, continuation includes a case where silence of less than one second to less than several seconds that may occur in a general conversation is regarded as continuation. 
     The cutting portion determining unit  63  determines a cutting portion from image data based on the speech time of each participant. The cutting portion includes one speaker or more. As illustrated in  FIGS. 2A to 3D , there may be case of one speaker or a case of plural speakers. The cutting portion determining unit  63  determines a cutting portion with coordinates of diagonal vertices in image data, for example. 
     The screen switching unit  64  creates a trimmed image  9  by cutting out a specified cutting portion from image data. In addition, when cutting out the cutting portion, a process to slightly move the cutting portion from a current cutting portion to a new cutting portion is performed (a sliding process or a zooming process described later). Accordingly, when the trimmed image  9  switches, many trimmed images  9  are created. In accordance with this, the trimmed images  9  are viewed as sliding. Or the trimmed images  9  are viewed as zooming out or zooming in. Further, the screen switching unit  64  determines a direction in which a spherical image is disposed such that a chairperson or a speaker is arranged northward. 
     &lt;From Start of Communication to Establishment of Session&gt; 
       FIG. 9  is a sequence diagram depicting a process in a preparation stage for start of communication among plural transmission terminals  10  the embodiment of the present invention. In  FIG. 9 , a process by which the transmission terminal  10   aa  prepares for start of communication with the transmission terminals  10   ac ,  10   ab , and  10   ad  is described. 
     First, when the user switches ON the power supply switch  109 , the operation input receiving unit  16  of the transmission terminal  10   aa  receives a power-on to switch the transmission terminal  10   aa  ON (step S 21 ). The log-in requesting unit  12  of the transmission terminal  10   aa  automatically transmits, upon reception of the power-on, log-in request information indicating a log-in request from the transmission and reception unit  11  to the transmission managing system  50  via the communication network  2  (step S 22 ). The log-in request can be transmitted not only upon the power-on but also at a given time through a user operation. In the log-in request information, a communication ID for identifying the transmission terminal  10   aa  as a requestor and a password are included. In addition, when the log-in request information is transmitted from the transmission terminal  10   aa  to the transmission managing system  50 , the transmission managing system  50  on a reception side can determine an “IP address” of the transmission terminal  10   aa . In addition, if the mobile terminal  20  is a requestor terminal, the operation input receiving unit  16  receives a log-in operation performed by the user and transmits the communication ID and the password to the transmission managing system  50 . 
     Next, the terminal authentication unit  52  of the transmission managing system  50  performs terminal authentication by determining whether the same communication ID and password as in the communication ID and password included in the log-in request information received via the transmission and reception unit  51  are managed (step S 23 ). In the description of the embodiment, it is assumed that authentication is successful. 
     If the terminal authentication unit  52  successfully authenticates the transmission terminal  10   aa , the state management unit  53  stores the communication ID, an “operation state,” and a “communication state” of the transmission terminal  10   aa , a “reception time” when the log-in request information is received, and the “IP address” of the transmission terminal  10   aa  in the terminal managing table in an associated manner (step S 24 ). In addition, the “operation state” at this moment is “Online.” 
     The transmission and reception unit  51  of the transmission managing system  50  transmits, via the transmission network  2 , authentication result information indicative of an authentication result obtained by the terminal authentication unit  52  to the transmission terminal  10   aa  that sent the log-in request (step S 25 ). 
     The terminal extraction unit  56  of the transmission managing system  50  searches the destination list managing table while using, as a search key, the communication ID “ 01   aa ” of the transmission terminal  10   aa  that sent the log-in request and extracts, by reading, communication IDs of candidates for a transmission terminal that can communication with the transmission terminal  10   aa  (step S 26 ). In this case, the communication IDs “ 01   ab ,” “ 01   ac ,” “ 01   ad ,” and “ 01   bb ” of the transmission terminals ( 10   ab ,  10   ac ,  10   ad , and  10   bb ) for the communication ID “ 01   aa ” of the transmission terminal  10   aa  are extracted. 
     Next, the terminal state obtaining unit  54  searches the terminal managing table while using, as a search key, the communication IDs (“ 01   ab ,” “ 01   ac ,” “ 01   ad ,” and “ 01   bb ”) of the transmission terminals  10   ab ,  10   ac ,  10   ad , and  10   bb  extracted by the terminal extraction unit  56  and the terminal state obtaining unit  54  reads an “operation state” for each communication ID (step S 27 ). In this case, it is assumed that the transmission terminals  10   ab ,  10   ac , and  10   ad  are “Online” and the transmission terminal  10   bb  is “Offline” for the sake of description. 
     Next, the transmission and reception unit  51  transmits destination state information in which the communication IDs (“ 01   ab ,” “ 01   ac ,” “ 01   ad ,” and “ 01   bb ”) extracted by the terminal extraction unit  56  and the “operation states” are included to the transmission terminal  10   aa  via the communication network  2  (step S 28 ). In accordance with this, the transmission terminal  10   aa  can determine the “operation state” of each of the transmission terminals ( 10   ab ,  10   ac ,  10   ad , and  10   bb ) at this moment, the transmission terminals being capable of communicating with the transmission terminal  10   aa.    
     Further, the terminal extraction unit  56  of the transmission managing system  50  searches the destination list managing table while using, as a search key, the communication ID “ 01   aa ” of the transmission terminal  10   aa  that sent the log-in request and extracts communication IDs of the transmission terminals  10  that register the communication ID “ 01   aa ” as a candidate for a destination terminal (step S 29 ). From the above destination list managing table, the communication IDs of the transmission terminals  10  to be extracted include “ 01   ab ,” “ 01   ac ,” “ 01   ad ,” and “ 01   bb.”   
     Next, the terminal state obtaining unit  54  of the transmission managing system  50  searches the terminal managing table while using, as a search key, the communication ID “ 01   aa ” of the transmission terminal  10   aa  that sent the log-in request and obtains the “operation state” of the transmission terminal  10   aa  (step S 30 ). 
     Then the transmission and reception unit  51  transmits, to the transmission terminals  10  whose the “operation state” is “Online” in the terminal managing table among the transmission terminals  10  having the communication IDs (“ 01   ab ,” “ 01   ac ,” “ 01   ad ,” and “ 01   bb ”) extracted in step S 29  above, destination state information in which the communication ID “ 01   aa ” of the transmission terminal  10   aa  and the “operation state” of “Online” obtained in step S 30  above are included (steps S 31 , S 32 , and S 33 ). Accordingly, the destination state information is transmitted to the transmission terminals  10   ab ,  10   ac , and  10   ad . In addition, when the transmission and reception unit  51  transmits the destination state information to the transmission terminals  10   ab ,  10   ac , and  10   ad , the transmission and reception unit  51  refers to, based on the communication IDs (“ 01   ab ,” “ 01   ac ,” and “ 10   ad ”), the “IP address” of the transmission terminals  10  managed in the terminal managing table. 
     When information about a destination list and the “operation states” of the candidates for a destination terminal are received, the destination list creating unit  21  of the transmission terminal  10   aa  creates a destination list screen and causes a display device  203  to display the destination list screen (step S 34 ). In this case, the destination list screen displays names of the transmission terminals  10   ab ,  10   ac , and Had and “Online” as the “operation states,” a name of the transmission terminal  10   bb  and “Offline” as the “operation state.” 
     By contrast, by performing the same process as in  FIG. 9  in the other transmission terminals  10   ab ,  10   ac , and  10   ad , the transmission terminals  10   ab ,  10   ac , and  10   ad  cause the display unit  120  to display a destination list screen having the transmission terminal  10   aa  as a destination candidate. 
       FIG. 10  is a sequence diagram depicting a process for establishing a session among plural transmission terminals  10  according to the embodiment of the present invention. 
     If the user presses the operation button  108  of the transmission terminal  10   aa  to select a destination terminal having the communication ID “ 01   ac ” displayed on the destination list screen, for example, the operation input receiving unit  16  receives a request to start connection (step S 41 ). 
     The transmission and reception unit  11  of the transmission terminal  10   aa  transmits start request information indicating a request to start connection to the transmission managing system  50 , the start request information including the communication ID “ 01   aa ” of the transmission terminal  10   aa  and the communication ID “ 01   ac ” of the destination terminal (step S 42 ). In accordance with this, the transmission managing system  50  determines the “IP address” of the requestor terminal (transmission terminal  10   aa ). 
     Next, the session management unit  55  of the transmission managing system  50  creates a “session ID” (step S 43 ). A unique ID is created as the “session ID.” 
     The created “session ID,” the communication ID “ 01   aa ” of the requestor terminal (transmission terminal  10   aa ), and the communication ID “ 01   ac ” of the destination terminal (transmission terminal  10   ac ) are stored and managed in an associated manner in the session managing DE 5005 (step S 44 ). Further, a conference ID is assigned. 
     Further, the session management unit  55  of the transmission managing system  50  determines a relay device  30  which is appropriate for communication between the requestor terminal and the destination terminal (step S 45 ). Examples of a method for determining the relay device  30  include selection of a relay device  30  having the widest reception and transmission bandwidth on the network. 
     In addition, a session may be directly established between the requestor terminal and the destination terminal without the selection of the relay device  30  or the session may be established via the transmission managing system  50 . 
     The transmission and reception unit  51  of the transmission managing system  50  transmits the “session ID” created in step S 43  and the “IP address” of the relay device  30  determined in step S 45  to the requestor terminal (transmission terminal  10   aa ) and the destination terminal (transmission terminal  10   ac ) (steps S 46  and S 47 ). 
     The display controlling unit  19  of the transmission terminal  10   ac  displays the communication ID of the requestor terminal (transmission terminal  10   aa ) on the display unit  120  (display device  203  in a case of the mobile terminal  20 ) and the operation input receiving unit  16  receives permission of a video conference from a user. Then the transmission and reception unit  11  of the transmission terminal  10   ac  transmits permission of start to the transmission managing system  50  (step S 47 - 1 ). 
     Next, the state management unit  53  of the transmission managing system  50  transmits, to the relay device  30 , the “IP address” and the communication ID of the requestor terminal (transmission terminal  10   aa ), the “IP address” and the communication ID of the destination terminal (transmission terminal  10   ac ), and the conference ID as relay start request information (step S 48 ). The relay device  30  manages the conference ID and the communication IDs in an associated manner in a relay managing table. Further, the relay device  30  assigns a unique data ID to the communication ID. The data ID may or may not be reported to each transmission terminal  10 . If the data ID is reported, the transmission terminal  10  assigns the data ID to content data and transmits the content data to the relay device  30 . If the data ID is not reported, the relay device  30  identifies the transmission terminal  10  based on the IP address or the like, assigns the data ID to content data, and transmits the content data to the transmission terminal  10 . 
     When the relay device  30  receives the communication IDs from the transmission managing system  50 , the relay device  30  detects that these are destinations of content data based on the communication IDs transmitted by the transmission terminals  10   aa  and  10   ac . In accordance with this, a session is established between the requestor terminal (transmission terminal  10   aa ) and the destination terminal (transmission terminal  10   ac ) (step S 49 ). When the session is established, the transmission terminal  10   aa  transmits content data to the transmission terminal  10   ac  via the relay device  30  and the transmission terminal  10   ac  transmits content data to the transmission terminal  10   aa  via the relay device  30 . 
     Next, the user of the transmission terminal  10   aa  transmits an invitation notice to the transmission managing system  50  (step S 50 ). The invitation notice is for allowing another transmission terminal  10  to participate in the video conference for which the session has been already established. The invitation notice includes the communication ID “ 01   aa ” of the transmission terminal  10   aa  that transmits the invitation notice and the communication IDs “ 01   ab ” and “ 01   ad ” of invited transmission terminals  10   ab  and  10   ad . Further, the transmission managing system  50  obtains the “IF address” of the transmission terminal  10   aa  that transmits the invitation notice. 
     When the transmission and reception unit  51  of the transmission managing system  50  receives the invitation notice, the terminal state obtaining unit  54  of the transmission managing system  50  obtains the “IP addresses” of the invited transmission terminals  10   ab  and  10   ad  from the terminal managing table. In accordance with this, the transmission and reception unit  51  of the transmission managing system  50  transmits the invitation notice to the transmission terminals  10   ab  and  10   ad  (step S 51 ). 
     The display controlling unit  19  of the transmission terminals  10   ab  and  10   ad  displays the communication ID of the requester terminal (transmission terminal  10   aa ) on the display unit  120  (display device  203  in a case of the mobile terminal  20 ), for example, such that the operation input receiving unit  16  receives a response to the invitation to the video conference from the user. In this case, it is assumed that the user accepts the invitation. Then the transmission and reception unit  11  of the transmission terminals  10   ab  and  10   ad  transmits the acceptance of invitation to the transmission managing system  50  (step S 52 ). 
     The session management unit  55  of the transmission managing system  50  assigns the same conference ID as in the transmission terminals  10   aa  and  10   ac  to the transmission terminals  10   ab  and  10   ad.    
     The transmission and reception unit  51  of the transmission managing system  50  transmits the acceptance of invitation to the transmission terminal  10   aa  that transmitted the invitation notice (step S 53 ). 
     Then the transmission and reception unit  51  of the transmission managing system  50  performs the processes of steps S 47  and S 48  for the invited transmission terminals  10   ab  and  10   ad , so that the transmission terminals  10   ab  and  10   ad  can participate in the session established between the transmission terminal  10   aa  and the transmission terminal  10   ac . In other words, the relay device  30  transmits (transfers) content data among the transmission terminals  10   aa ,  10   ac ,  10   ab , and  10   ad  having the same conference ID. 
     Thereafter, content data is transmitted and received among the requestor terminal (transmission terminal  10   aa ), the destination terminal (transmission terminal  10   ac ), and the invited transmission terminals  10   ab  and  10   ad  via the relay device  30 . 
     &lt;Conversion of Image Data about 360-Degree Surroundings into Planar Image Data&gt; 
     An image captured by the spherical camera  112   a  is represented in a format as illustrated in  FIG. 11A , for example.  FIG. 11A  is a diagram schematically illustrating spherical image data according to the embodiment of the present invention. The spherical image data provides a field of view of 360 degrees in the horizontal direction and 180 degrees in the vertical direction, so that an image of surroundings in all directions is captured. 
     Coordinates (θ, φ) of the spherical image data illustrated in  FIG. 11A  and coordinates (x, y) of a planar image have the relationships defined by Equation (1) below. 
     
       
         
           
             
               
                 
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     It is possible to convert the spherical image data into planar image data illustrated in  FIG. 11B  by using these relationships. In addition, Equation (1) is expressed on the assumption that the zenithal direction of the spherical image data corresponds to a direction orthogonal to the ground. 
     In addition, a half field of view (angle formed between an end of a photographic subject and an optical axis of a lens) of the planar image is set in accordance with an area for capturing an image of participants. Because the maximum value of the half field of view of the planar image is 90 degrees (divergence occurs at 90 degrees), the half field of view is preferably set to 75 degrees at most. Accordingly, the area for capturing an image of participants may be determined to have 75 degrees upward or downward (latitudinal direction) from the horizontal direction. Alternatively, facial recognition is performed on the spherical image data without modification and the maximum value and the minimum value of locations of the faces of all of the participants in the latitudinal direction are obtained. Then the half field of view may be determined such that at least the maximum value and the minimum value are included. 
     In the following, x and θ, and y and φ are not discriminated from each other for convenience sake of description. The horizontal direction is described as θ and the vertical direction is described as φ. 
     &lt;Detection of Participants from Image Data&gt; 
       FIG. 12  is a diagram schematically illustrating planar image data converted from spherical image data or a part of the spherical image data according to the embodiment of the present invention. The participant detecting unit  61  performs a facial recognition process on such image data. In addition, the facial recognition may be performed on a planar image or the spherical image data without modification. 
     As to the participant detecting unit  61 , classifiers learn with Boosting in advance using a huge amount of learning data. In the Boosting, by determining weight α T  of plural weak classifiers h T  (T indicates the number of weak classifiers) not having a high recognition rate, the classifiers are caused to learn to be able to correctly classify learning data. 
     
       
         
           
             
               
                 
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     In Equation (2), ht(x) indicates feature amount for classification, α T  indicates weight of the feature amount for classification, and T indicates the number of pieces of feature amount for classification. If a calculation result H(x) of Equation (2) exceeds a threshold, the face is determined to be included. The participant detecting unit  61  divides image data into rectangular areas and performs calculation of Equation (2) for each rectangular area. The participant detecting unit  61  performs the facial recognition at high speed by calculating Equation (2) using only those top several tens of weak classifiers having a large weight α r . 
     As for the weak classifiers, there are Haar-like weak classifiers and weak classifiers using reference vectors. However, the weak classifiers are not limited to these weak classifiers. 
       FIG. 12  illustrates the faces of participants recognized in this manner with a rectangular frame  31 . A location of the rectangular frame  31  is specified in the longitude θ and the latitude φ. For example, the face of a participant A is included in the rectangular frame  31  defined by (θ A1 , φ A1 ) (θ A2 , φ A2 ) as diagonal vertices. In the same manner, the rectangular frames  31  of participants B to F are defined by (θ B1 , φ B1 ) (θ B2 , φ B2 ), (θ C1 , φ C1 ) (θ C2 , φ C2 ), (θ D1 , φ D1 ) (θ D2 , φ D2 ), (θ E1 , φ E1 ) (θ E2 , φ E2 ), and (θ F1 , φ F1 ) (θ F2 , φ F2 ). These are examples of a participant location. 
     Image data is updated periodically (the camera  112  repeats imaging at a predetermined frame rate), so that the participant detecting unit  61  uses locations of participants recognized in the past to recognize the faces from the image data. In other words, for the participant A, the facial recognition may be performed only on the vicinity of the rectangular frame  31  (θ A1 , φ A1 ) (θ A2 , φ A2 ), so that it is possible to constantly monitor the participant location. 
     In a single-display mode, the cutting portion determining unit  63  determines a cutting portion in consideration of a margin at the participant location detected by the participant detecting unit  61 . For example, the cutting portion determining unit  63  determines the cutting portion while enlarging the length of sides of the rectangular frame  31  by 10 to 20%. Cutting portions in a plural-display mode will be described with reference to  FIGS. 36A to 36C . 
     &lt;Detection of Speaker Direction&gt; 
     The speaker direction estimating unit  14  detects a sound source direction from voice sound data input by the voice sound input unit  13 . In the embodiment, a method by which the speaker direction estimating unit  14  detects the sound source direction based on a difference of an arrival time of voice sound input into a microphone array is described. 
       FIG. 13  is a diagram illustrating a principle for detecting a sound source direction performed by the speaker direction estimating unit  14  according to the embodiment of the present invention. First and second microphones are disposed with an interval L in the horizontal direction. If voice sound arrives from a direction  6 , voice sound detected by the first microphone is detected by the second microphone with a delay of a time t. This time t is expressed as follows, where v indicates the speed of sound.
 
Time  t =( L ·cosδ)/ v   (3)
 
     Accordingly, if L and V are constant and the time t is determined, it is possible to obtain δ. The time t is calculated from a cross-correlation value between voice sound data s 1 ( t ) obtained by the first microphone and voice sound data s 2 ( t +dt) obtained by the second microphone, for example. A cross-correlation value C(t,dt) is calculated from Equation (4). 
     
       
         
           
             
               
                 
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     Equation (4) indicates that a multiply-accumulate operation is performed using N samples before a time t. N is a positive integer indicating the size of a correlation window. Although a detailed description is omitted, dt that maximizes C(t,dt) is the above delayed time t. 
     In  FIG. 13 , there are only two microphones  114 , so that it is possible to detect only 0 with a range of 0 to 180 degrees. Accordingly, third and fourth microphones are disposed as another pair orthogonally to a direction in which the first and second microphones are disposed. In accordance with this, it is possible to detect a sound source direction in a range of 360 degrees in the horizontal direction. 
     If the camera  112  and microphones  114  are integrally formed and in accordance with arrangement of one of the camera  112  and the microphones  114 , arrangement of the other is automatically determined, the user may dispose the camera  112  and the microphones  114  on a desk or the like without paying special attention. In contrast, if the camera  112  and the microphones  114  are separately formed (if the camera  112  and the microphones  114  can be separately disposed), the user aligns the camera  112  and the microphones  114  on the desk, for example. In accordance with this, it is possible to match a criterion for the horizontal direction of a speaker with a criterion for the longitudinal direction of image data. 
     In addition, the microphones  114  may not be used for the detection of the speaker. For example, the speaker direction estimating unit  14  analyzes image data to detect a participant who opens and closes or moves the mouse as the speaker. 
     &lt;Association of Participant Location with Speaker Direction&gt; 
     The speech time measuring unit  62  associates a participant location obtained as described above with a speaker direction as follows. First, the speech time measuring unit  62  uses the center of the rectangular frame  31  in the longitudinal direction as the participant location. This is because speaker directions are distributed only in the longitudinal direction. However, if the speaker directions are also distributed in the latitudinal direction, the center of the rectangular frame  31  in the longitudinal direction and the latitudinal direction may be used. 
       FIG. 14  is a diagram illustrating a speaker direction according to the embodiment of the present invention. It is assumed that participants A to F are present in the longitudinal direction and the speaker direction estimating unit  14  obtains a speaker direction at “a” degrees of the longitude θ, for example. In this case, the speech time measuring unit  62  associates the speaker direction with a participant at a participant location closest to the “a” degrees of the longitude θ. Because participant locations of the participants are expressed by (θ X1 +θ X2 )/2, where (X: A to F), a participant location having a minimum absolute value of difference between these locations and the “a” degrees of the longitude θ is specified. When speaker directions at “b” degrees of the longitude θ to “f” degrees of the longitude θ are detected, it is possible to associate the speaker directions with participant locations in the same manner. 
     In this manner, it is possible to detect a speaker and participants. The speech time measuring unit  62  measures a speech time for each participant detected based on the speaker direction and the participant location. 
     &lt;Display Modes and Options&gt; 
     In the following, display modes and options to be selected by the user of the transmission terminal  10   aa  are described. The transmission terminal  10  has three display modes and options that can be set in each display mode by the user. Display modes: single-display mode, plural-display mode, and 360-degree-display mode 
     In the single-display mode, the screen switching unit  64  trims only one speaker. 
     In the plural-display mode, the screen switching unit  64  trims, from image data, an area in which a predetermined number of speakers is included. The number of persons displayed at a time is increased, so that frequency of screen switching is reduced in comparison with the single-display mode. Accordingly, screen transition preferable for a user that views the display unit  120   ab  of the transmission terminal  10   ab  is likely to be obtained. In contrast, the plural-display mode has a disadvantage in that the size of the faces of participants is reduced. 
     In the 360-degree-display mode, image data on all directions is constantly displayed. Because a 360-degree area is captured in spherical image data, the spherical image data is displayed without modification. In addition, the transmission terminal  10   aa  may convert the spherical image data into a panoramic image which is horizontally long. Because the entire portion is constantly displayed, screen transition is eliminated and so the user can constantly get a full view of all participants of a conference by viewing a single screen. In contrast, a spherical image is circular, so that some users may not be used to such an image. Further, when the spherical image data is converted into the panoramic image, a portion which is originally straight may be seen as warped, so that this may lead to stress for the user. 
       FIG. 15A  is a diagram illustrating a display mode selecting screen  501  rendered on the display unit  120   aa  of the transmission terminal  10   aa  according to the embodiment of the present invention. On the display mode selecting screen  501 , radio buttons  502  are displayed along with the above three display modes. The user of the transmission terminal  10   aa  selects one of the display modes from the radio buttons  502  and presses an OK button  503 . The operation input receiving unit  16  of the transmission terminal  10   aa  receives the selection made by the user and the trimming unit  18  changes the display mode selecting screen  501  to a screen corresponding to the selected display mode. In addition, if a cancel button  504  is pressed, the operation input receiving unit  16  does not receive the setting of the display mode. In this case, a display mode that has been set last is enabled. 
       FIG. 15B  is a diagram illustrating a screen  510  for selecting options in the single-display mode according to the embodiment of the present invention. The screen  510  for selecting options in the single-display mode has a switching time setting field  511 . In the switching time setting field  511 , the user sets how long a speaker should continue to speak so that the trimmed images  9  are switched. In  FIG. 15B , the time is set to 20 seconds. The user can set a desired switching time within a range having a lower limit and an upper limit determined in advance. 
     Further, the screen  510  for selecting options in the single-display mode has a “90-degree screen switching option,” a “two-screen option,” a “speed-change option”, and radio buttons  512  for the options. The user selects a desired option and presses the OK button  503 . The operation input receiving unit  16  of the transmission terminal  10   aa  receives the setting of the option made by the user. In addition, if the cancel button  504  is pressed, the operation input receiving unit  16  does not receive the setting of the option. Whether to set the option is arbitrarily determined by the user. 
     The “90-degree screen switching option,” the “two-screen option,” and the “speed-change option” will be described later. 
       FIG. 16A  is a diagram illustrating a screen  520  for selecting options in the plural-display mode according to the embodiment of the present invention. The screen  520  for selecting options in the plural-display mode has a counting time setting field  521 . In the counting time setting field  521 , the user sets frequency at which the trimmed images  9  including plural speakers are switched. In  FIG. 16A , the time is set to 3 minutes. The user can set a desired counting time within a range having a lower limit and an upper limit determined in advance. 
     Further, the screen  520  for selecting options in the plural-display mode also has a field  522  for setting the number of speakers. In the field  522  for setting the number of speakers, the user sets the number of speakers to be included in the trimmed image  9 . In  FIG. 16A , the number is set to 2. The user can set a desired number of speakers within a range having a lower limit and an upper limit determined in advance. 
     Further, the screen  520  for selecting options in the plural-display mode also has a “chairperson option,” a “90-degree screen switching option,” a “two-screen option,” a “speed-change option,” and radio buttons  523  for the options. The user selects a desired option and presses the OK button  503 . The operation input receiving unit  16  of the transmission terminal  10   aa  receives the setting of the option made by the user. In addition, if the cancel button  504  is pressed, the operation input receiving unit  16  does not receive the setting of the option. Whether to set the option is arbitrarily determined by the user. 
     The “90-degree screen switching option,” the “two-screen option,” and the “speed-change option” are the same as in the screen  510  for selecting options in the single-display mode. The “chairperson option” will be described later. 
     If the radio button  523  for the “chairperson option” is selected, the display controlling unit  19  displays a chairperson option screen  530  illustrated in  FIG. 16B  in a pop-up window. The chairperson option screen  530  has a “set chairperson” option, a “use speech time” option, and radio buttons  531  for the options. In the “set chairperson,” the user selects a chairperson. In the “use speech time,” the user sets a participant that has the longest speech time as the chairperson. 
     Further, if the “set chairperson” option is selected, the display controlling unit  19  displays image data illustrated in  FIG. 16C . This image data may be spherical image data captured in real time by the camera  112  or may be a converted planar image. The user presses a given participant using a mouse or the finger. The operation input receiving unit  16  reports a pressed location (coordinates, for example) in the image data to the trimming unit  18 . Because participant locations have been detected using facial recognition, the trimming unit  18  determines a participant closest to the pressed location as the chairperson. 
       FIG. 17  is a diagram illustrating a screen  540  for selecting options in the 360-degree-display mode according to the embodiment of the present invention. The screen  540  for selecting options in the 360-degree-display mode has a “fix chairperson” option, a “fix participants” option, an “emphasize speaker” option, and radio buttons  541  for the options. The user selects a desired option and presses the OK button  503 . The operation input receiving unit  16  of the transmission terminal  10   aa  receives the setting of the option made by the user. In addition, if the cancel button  504  is pressed, the operation input receiving unit  16  does not receive the setting of the option. Whether to set the option is arbitrarily determined by the user. 
     The screen  540  for selecting options in the 360-degree-display mode also has a switching time setting field  542  which is enabled only if the “emphasize speaker” option is selected. In the switching time setting field  542 , a time to switch speakers is set. 
     The “fix chairperson” option, the “fix participants” option, and the “emphasize speaker” option will be described later. 
     &lt;Operation Procedure of Transmission Terminal&gt; 
       FIG. 18  is a flowchart illustrating a flow of an overall operation in the transmission terminal  10  according to the embodiment of the present invention. 
     On the display mode selecting screen  501 , the operation input receiving unit  16  of the transmission terminal  10  receives selection of any one of the single-display mode, the plural-display mode, and the 360-degree-display mode (step S 10 ). 
     If the single-display mode is selected, the trimming unit  18  of the transmission terminal  10  operates in the single-display mode (step S 20 ). 
     If the plural-display mode is selected, the trimming unit  18  of the transmission terminal  10  operates in the plural-display mode (step S 30 ). 
     If the 360-degree-display mode is selected, the trimming unit  18  of the transmission terminal  10  operates in the 360-degree-display mode (step S 40 ). 
     &lt;&lt;Single-Display Mode&gt;&gt; 
       FIG. 19  is a flowchart illustrating a processing procedure of the transmission terminal  10  in the single-display mode according to the embodiment of the present invention. The processing procedure in  FIG. 19  starts when the single-display mode is selected and a video conference is started. 
     When the video conference is started, the speaker direction estimating unit  14  of the transmission terminal  10  waits for a start of speech (step S 10 ). 
     The speaker direction estimating unit  14  monitors the voice sound input unit  13  or the like to determine whether a speech starts (step S 20 ). In addition, the participant detecting unit  61  waits until the speech starts. 
     If the speech starts (Yes in step S 20 ), the speech time measuring unit  62  starts a single-speaker timer for measuring a speech time of a speaker (step S 30 ). The single-speaker timer is for measuring a continuous speech time of the speaker. 
     The speech time measuring unit  62  of the transmission terminal  10  monitors the single-speaker timer (step S 40 ) and determines whether a time measured by the single-speaker timer exceeds a switching time (step S 50 ). Although the switching time is set to be 20 seconds in  FIG. 19 , the switching time may be set such that frequent changes of the screen can be prevented. 
     If a result of the determination in step S 50  is No, the speech time measuring unit  62  determines whether the speech ends (step S 60 ). 
     If the speech does not end (No in step S 60 ), the process returns to step S 40  and the single-speaker timer is continuously monitored. 
     If the speech ends (Yes in step S 60 ), the process returns to step S 10  and the transmission terminal  10  waits for a start of speech again. Accordingly, if the speech ends before the time of the single-speaker timer reaches the switching time, the trimming unit  18  does not switch trimmed images  9 . 
     In addition, whether the speech ends is determined based on whether the speech of the speaker is not detected continuously for 10 seconds, for example. In other words, the determination may be based on a condition of no speech for a predetermined time or more. 
     If the result of the determination in step S 50  is Yes, the speech time measuring unit  62  clears the single-speaker timer (step S 70 ). 
     Then the trimming unit  18  trims an area that includes the speaker from image data (step S 80 ). In other words, the cutting portion determining unit  63  determines a cutting portion and the screen switching unit  64  creates a trimmed image  9  by cutting out the determined cutting portion. 
     The speech time measuring unit  62  determines whether the speech ends (step S 90 ). Until the speech ends, trimmed images  9  including the speaker that continues the speech are created. 
     If the speech ends (Yes in step S 90 ), the process returns to step S 10  and the transmission terminal  10  waits for a start of speech again. Accordingly, after the speech ends, if there is a participant that continuously speaks for the switching time or more, the trimmed image  9  is changed. In accordance with the above process, screen transition as illustrated in  FIGS. 2A to 2C  is obtained. 
     (Screen Transition in Single-Display Mode) 
       FIG. 20  is a time chart illustrating screen transition in the single-display mode according to the embodiment of the present invention. In  FIG. 20 , three persons (A, B, and C) are participants. The abscissa indicates time and the ordinate indicates a participant included in the trimmed image  9  (participant displayed on the display unit  120   ab  of the transmission terminal  10   ab ), a speech state of the participant C, a speech state of the participant B, and a speech state of the participant A from the top. 
     Time t 1 : First, the participant A starts a speech. At this moment, any one of the participants may be included in the trimmed image  9 . 
     Time t 2 : Because 20 seconds have elapsed since the participant A started the speech, the screen switching unit  64  trims an area in which the participant A is included. Accordingly, the participant A is displayed on the display unit  120   ab  of the transmission terminal  10   ab.    
     Time t 3 : The participant A ends the speech and the participant B starts a speech. At this moment, the trimmed image  9  is unchanged because 20 seconds have not elapsed since the participant B started the speech. 
     Time t 4 : Because 20 seconds have elapsed since the participant B started the speech, the screen switching unit  64  trims an area in which the participant B is included. Accordingly, the participant B is displayed on the display unit  120   ab  of the transmission terminal  10   ab.    
     Time t 5 : The participant A starts a speech. 
     Time t 6 : The participant A ends the speech before 20 seconds have elapsed. Accordingly, the participant B is still included in the trimmed image  9 . 
     Time t 7 : The participant C starts a speech. However, the participant B is still included in the trimmed image  9  because a speech time of the participant C does not reach 20 seconds. 
     Time t 8 : The participant B resumes the speech. 
     Time t 9 : Although the participant B resumed the speech and 20 seconds or more have elapsed, the participant B is still included in the trimmed image  9 . 
     Time t 10 : The participant B ends the speech and the participant A starts a speech. 
     Time t 11 : Because 20 seconds have elapsed since the participant A started the speech, the screen switching unit  64  trims an area in which the participant A is included. Accordingly, the participant A is displayed on the display unit  120   ab  of the transmission terminal  10   ab.    
     As described above, at least 20 seconds are necessary to switch the trimmed images  9 . Accordingly, even if plural participants are captured in a spherical image and the participants successively speak, it is possible to prevent frequent changes of the screen displayed on the display unit  120   ab  of the transmission terminal  10   ab.    
     &lt;&lt;Plural-Display Mode&gt;&gt; 
       FIG. 21  is a flowchart illustrating a processing procedure of the transmission terminal  10  in the plural-display mode according to the embodiment of the present invention. The processing procedure in  FIG. 21  starts when the plural-display mode is selected and a video conference is started. 
     When the video conference is started, the speech time measuring unit  62  starts a plural-speaker timer (step S 10 ). The plural-speaker timer is for measuring the above counting time. When the speech time measuring unit  62  starts the plural-speaker timer, the speech time measuring unit  62  starts measuring an accumulated speech time of each participant. 
     Next, the trimming unit  18  determines whether a chairperson is set in advance (step S 20 ). In other words, the trimming unit  18  determines whether the chairperson option is selected in the screen  520  for selecting options in the plural-display mode. 
     If a result of the determination in step S 20  is Yes, the trimming unit  18  determines, among participants, a participant selected by the user to be the chairperson (step S 30 ). 
     Next, the speech time measuring unit  62  waits until the plural-speaker timer finishes counting the counting time (step S 40 ). This is for detecting speakers from a second speaker. 
     If the result of the determination in step S 20  is No, the speech time measuring unit  62  waits until the plural-speaker timer finishes counting the counting time (step S 50 ). 
     When the plural-speaker timer finishes counting the counting time (Yes in step S 50 ), the speech time measuring unit  62  determines a participant having the longest speech time within the counting time to be the chairperson (step S 60 ). 
     Next, the speech time measuring unit  62  successively determines participants from the second longest speech time (step S 70 ). The number of participants to be determined is set in the field  522  for setting the number of speakers of the screen  520  for selecting options in the plural-display mode. 
     Next, the cutting portion determining unit  63  determines a cutting portion that includes plural speakers having longer speech times and the screen switching unit  64  creates a trimmed image  9  by cutting out the determined cutting portion from image data (step S 80 ). 
     The speech time measuring unit  62  clears the plural-speaker timer (step S 90 ). 
     Then the speech time measuring unit  62  waits until the plural-speaker timer finishes counting the counting time (step S 100 ). Then the process proceeds to step S 70  and a cutting portion is determined each time the counting of the counting time is finished. 
     According to the above process, the transmission terminal  10   aa  can determine speakers in descending order of the amount of speech during the counting time and includes plural higher-ranking speakers in the trimmed image  9 . The trimmed image  9  is maintained without modification during the counting time and each time the counting time has elapsed, the speech time is measured again from zero. Accordingly, because the counting time is necessary to switch the trimmed images  9 , it is possible to prevent frequent changes of the screen displayed on the display unit  120   ab  of the transmission terminal  10   ab.    
     (Measurement of Speech Time) 
       FIG. 22  is a flowchart illustrating a procedure for measuring a speech time by the speech time measuring unit  62  according to the embodiment of the present invention.  FIGS. 23A and 23B  are diagrams schematically illustrating an accumulated speech time of a participant according to the embodiment of the present invention. 
     The process in  FIG. 22  starts when measurement performed by the plural-speaker timer starts in  FIG. 21 . 
     When the speech time measuring unit  62  starts the plural-speaker timer (Yes in step S 10 ), the speech time measuring unit  62  starts accumulating a speech time for each participant (step S 20 ). 
     Next, the speech time measuring unit  62  determines whether the plural-speaker timer has timed out (step S 30 ). 
     When the plural-speaker timer has times out, the speech time measuring unit  62  clears the speech time of all participants (step S 40 ). 
     Then the process returns to step S 20  and the speech time measuring unit  62  starts accumulating the speech time for each participant. 
     In accordance with such a process, the speech time of participants is obtained as illustrated in  FIGS. 23A and 23B .  FIGS. 23A and 23B  indicate the speech time accumulated in a case where the plural-speaker timer is cleared each time the plural-speaker timer measures 5 minutes.  FIG. 23A  indicates an accumulated speech time in 0 to 5 minutes.  FIG. 23B  indicates an accumulated speech time in 5 to 10 minutes. 
     As illustrated in  FIG. 23A , during the 5 minutes at the beginning of the video conference, the participants A and B are top  2  participants in the accumulated speech time. Accordingly, the cutting portion determining unit  63  determines, as a cutting portion, an area in which the participants A and B are included. 
     As illustrated in  23 B, during the next 5 minutes, the participants A and D are top  2  participants in the accumulated speech time. Accordingly, the cutting portion determining unit  63  determines, as a cutting portion, an area in which the participants A and D are included. If the participants A and D are not adjacent to each other, other participants between the participants A and D are included in the trimmed image  9 . In accordance with the above process, screen transition as illustrated in  FIGS. 3A to 3D  is obtained. 
     &lt;Trimmed Image in Single-Display Mode and Plural-Display Mode&gt; 
     &lt;&lt;Control Upon Switching Trimmed Image&gt;&gt; 
     In the embodiment, spherical image data is obtained, so that control to change a direction of the camera  112  to select a captured participant is unnecessary. However, if the trimmed images  9  are switched instantaneously, the user may find it hard to determine arrangement of participants. Accordingly, in the embodiment, switching of the trimmed images  9  is performed as if the camera  112  were gradually changing its direction. 
       FIGS. 24A and 24B  are diagrams illustrating switching of trimmed images  9  according to the embodiment of the present invention. Control to switch the trimmed images  9  is common in the single-display mode and in the plural-display mode, so that  FIG. 24A  is described as control in the single-display mode. First, the participant A is included in the trimmed image  9 . If the participant D is to be included next in the trimmed image  9  based on a speech time, the screen switching unit  64  gradually moves the trimmed image  9  from the participant A to the participant D. 
       FIG. 243  is a diagram illustrating intermediate images  8  during switching of the trimmed images  9 . As illustrated in  FIG. 243 , the intermediate images  8  from a trimmed image  9   a  to a trimmed image  9   d  are trimmed. Such a process is referred to as a sliding process of the trimmed image  9 . The intermediate images  8  are determined as follows. 
     (i) Four vertices of the trimmed image  9   a  and the trimmed image  9   d  (namely, cutting portions determined by the cutting portion determining unit  63 ) are obtained. The vertices of the trimmed image  9   a  before switching are K 1 , K 2 , K 3 , and K 4  and the vertices of the trimmed image  9   d  after the switching are M 1 , M 2 , M 3 , and M 4 .
 
(ii) The number of the intermediate images  8  used in the sliding process is set to n and points that divide straight lines that connect K 1  and M 1 , K 2  and M 2 , K 3  and M 3 , and K 4  and M 4  into n equal parts are obtained, where n is a variable determined depending on an amount of sliding.
 
(iii) Quadrangles obtained by connecting corresponding points that divide the straight lines into n equal parts are determined to be the intermediate images  8  used in the sliding process.
 
     Accordingly, on the display unit  120   ab  of the transmission terminal  10   ab , the trimmed images  9  are displayed as if the camera  112  were gradually changing its direction. When the trimmed images  9  are switched from the participant D to the participant A, the sliding process is performed in the same manner. 
     In addition, a direction of sliding may be determined to have a smaller amount of sliding between a direction for a greater longitude θ and a direction for a smaller longitude θ. Accordingly, the maximum amount of sliding is 180 degrees. Although the same sliding process is performed in the plural-display mode, a supplementary description will be given with reference to  FIG. 35 . 
     In the following, a zoom-out process is described. In the sliding process, the trimmed images  9  are switched while the original size is maintained. By contrast, in the zoom-out process, the size of the trimmed image  9  is increased. However, a specific process is substantively the same. 
       FIGS. 25A and 25B  are diagrams illustrating switching of trimmed images  9  in a zoom-out process according to the embodiment of the present invention.  FIG. 25A  illustrates a case of the plural-display mode and the participants A and B are included in a trimmed image  9   ab . If the participants A and D are to be included next in a trimmed image  9   ad  based on a speech time, the screen switching unit  64  gradually enlarges the current trimmed image  9   ab  up to the trimmed image  9   ad  that includes the participants A and D. 
     The screen switching unit  64  performs the zoom-out process as follows, for example. 
     (i) Four vertices of the trimmed image  9  before switching and the trimmed image  9  after the switching are obtained. The vertices of the trimmed image  9  before the switching are K 1 , K 2 , K 3 , and K 4  and the vertices of the trimmed image  9  after the switching are M 1 , M 2 , M 3 , and M 4 .
 
(ii) The number of images used in the zoom-out process is set to n and points that divide straight lines that connect K 1  and M 1 , K 2  and M 2 , K 3  and M 3 , and K 4  and M 4  into n equal parts are obtained.
 
(iii) Quadrangles obtained by connecting corresponding points that divide the straight lines into n equal parts are determined to be the intermediate images  8  used in the zoom-out process.
 
       FIG. 25B  is a diagram illustrating trimmed images  9  during the switching. In  FIG. 25B , areas from the trimmed image gab to the trimmed image  9   ad  are trimmed as intermediate images  8 . Such a process is referred to as zooming out in the trimmed image  9 . Accordingly, on the display unit  120   ab  of the transmission terminal  10   ab , trimmed images  9  are displayed as if the camera  112  were gradually zooming out. 
     In addition, an area not present in the original image data may be trimmed in order to maintain an aspect ratio. In this case, black pixels, white pixels, a pattern, a geometric pattern, or the like may be arranged in the area not present in the original image data. 
     By contrast, if the trimmed image  9   ad  is switched to the trimmed image  9   ab , a zoom-in process is performed. In other words, areas from the trimmed image  9   ad  to the trimmed image  9   ab  are trimmed. 
     In addition, if the participants A and F are trimmed, for example, the cutting portion determining unit  63  does not need to determine all of the participants A to F to be a cutting portion. This is because the image data includes a range of 360 degrees, the participant F and the participant A are actually adjacent to each other. Accordingly, the cutting portion determining unit  63  may determine the cutting portion to include the participants F and A. In other words, when the cutting portion determining unit  63  determines the cutting portion to include plural participants, the cutting portion determining unit  63  determines the cutting portion such that a field of view provided by the cutting portion is reduced in the longitudinal direction. 
     &lt;&lt;90-Degree Screen Switching Option&gt;&gt; 
       FIGS. 24A and 24B  illustrate the sliding process. If the amount of sliding is excessively greater in the sliding process, this may cause screen transition that is not preferable for the user to the contrary. In such a case, the 90-degree screen switching option is used to restrict the amount of sliding. 
       FIGS. 26A and 26B  are diagrams illustrating the trimmed images  9  when the 90-degree screen switching option is selected according to the embodiment of the present invention. In  FIG. 26A , the participant A is included in the trimmed image  9   a . If the participant E is to be included next in a trimmed image  9   e  based on a speech time, the screen switching unit  64  calculates an amount of movement  601  of the trimmed image  9   a  in the longitudinal direction. If the amount of movement  601  exceeds ±90 degrees, the screen switching unit  64  determines an area in which the participant E is included to be a cutting portion without performing the sliding process on the trimmed image  9 . 
     Accordingly, as illustrated in  FIG. 26B , after the trimmed image  9   a , the trimmed image  9   e  is trimmed. If the amount of sliding is greater, it is possible to provide screen transition preferable to the user by eliminating the sliding process. 
     Although  FIGS. 26A and 26B  illustrate the single-display mode, determination in the plural-display mode is made in the same manner. Further, as to the zoom-out process/zoom-in process, if an amount of change of the size of the trimmed image  9  exceeds 90 degrees, the zoom-out process/zoom-in process is not performed. Alternatively, the zoom-out process/zoom-in process may be performed based on a user setting, for example. 
     The ±90 degrees is an example and the sliding process may not be performed if the amount of sliding in a range of 90 to 180 degrees is greater than a threshold (the maximum value of the amount of movement  601  is 180 degrees), for example. This threshold may be set by the user. 
     &lt;&lt;Two-Screen Option&gt;&gt; 
     In the two-screen option, the screen switching unit  64  divides a 360-degree image into two 180-degree images, creates a trimmed image  9  from each 180-degree image, and transmits two image data to the transmission terminal  10  participating in a video conference. 
       FIG. 27  is a diagram illustrating the two-screen option according to the embodiment of the present invention. The cutting portion determining unit  63  determines cutting portions such that the cutting portions include a participant having the longest speech time in a field I of 0 to 179 degrees and in a field II of 180 to 360 degrees. 
     Accordingly, two trimmed images  9  are transmitted to the transmission terminal  10   ab . The user of the transmission terminal  10   ab  can select and display only one of the trimmed images  9  or display the two trimmed images  9  at a time. Because an opportunity for displaying participants is doubled, frequency of switching the trimmed images  9  is reduced. Further, it is possible to realize a video conference with presence. 
     Although  FIG. 27  illustrates the single-display mode, a process in the plural-display mode is performed in the same manner. If a participant is present at a boundary between the field I and the field II, the field I is shortened forward or elongated backward. Whether to shorten or elongate is determined such that the number of participants becomes nearly equal. 
     &lt;&lt;Speed-Change Option&gt;&gt; 
     In the speed-change option, a sliding speed of the trimmed image  9  in the sliding process is controlled. 
       FIG. 28A  is a diagram illustrating the speed-change option according to the embodiment of the present invention. If the speed-change option is selected, the screen switching unit  64  slides the trimmed image  9  at low speed immediately after a movement start  611  and immediately before a movement end  613  (predetermined ranges) and at high speed in a middle portion  612  (outside the predetermined ranges). 
     Specifically, the screen switching unit  64  determines that the trimmed image  9  is taken at trimming intervals Δ 1  in the predetermined ranges of the trimmed image  9   a  as a movement source and the trimmed image  9   e  as a movement destination. The screen switching unit  64  also determines that the trimmed image  9  is taken at trimming intervals Δ 2  outside the predetermined ranges. Because Δ 1 &lt;Δ 2 , the trimmed image  9  slides at low speed immediately after the movement start  611  and immediately before the movement end  613  and the trimmed image  9  slides at high speed in the middle portion  612 . Because Δ 1  and Δ 2  are determined by the above n used to divide the straight lines into n equal parts, n may be changed immediately after the movement start  611  (immediately before the movement end  613 ) and in the middle portion  612 . 
     Alternatively, intervals of the trimmed images  9  may be successively changed.  FIG. 28B  is a diagram illustrating trimming intervals Δ relative to an amount of sliding according to the embodiment of the present invention. The trimming intervals Δ are determined to turn back at a middle point of the amount of sliding. The trimming intervals gradually increase from an initial value Δs and when the amount of sliding is determined to pass through the middle point, the trimming intervals gradually decrease toward the initial value Δs. Although the trimming intervals reach a maximum value Δmax at the middle point between the movement source and the movement destination, the maximum value Δmax changes depending on the amount of sliding. Accordingly, the trimmed image  9  slides at low speed immediately after the movement start and immediately before the movement end, and the trimmed image  9  can slide at higher speed in the middle portion as the amount of sliding increases. 
     Although  FIGS. 28A and 28B  illustrate the single-display mode, a process in the plural-display mode is performed in the same manner. Further, if the amount of sliding is equal to or less than a predetermined amount, the screen switching unit  64  may not perform the speed change. This is because if the amount of sliding is little, the speed change may provide an uncomfortable feeling to the user. 
     &lt;&lt;Chairperson Option&gt;&gt; 
     In the chairperson option, the screen switching unit  64  always includes the chairperson in the trimmed image  9 . In addition, the chairperson option is available only in the plural-display mode. 
       FIGS. 29A to 29C  are diagrams illustrating the chairperson option according to the embodiment of the present invention. In  FIGS. 29A to 29C , the participant C is assumed to be the chairperson. The chairperson is selected by the user, or a participant having the longest speech time is determined to be the chairperson. Further, in the  FIGS. 29A to 29C , two persons are assumed to be selected as speakers. Accordingly, other than the chairperson, another participant having the longest speech time is specified as the speaker. 
     In  FIG. 29A , the participant D is determined to have the longest speech time, so that a trimmed image  9   cd  in which the chairperson C and the participant D are included is created. 
     In the next counting time, the participant E is assumed to be determined as having the longest speech time. As illustrated in  FIG. 29B , the cutting portion determining unit  63  determines a cutting portion in which persons from the chairperson C to the participant E are included. In accordance with this, a trimmed image  9   cde  is created. 
     In the next counting time, the participant A is assumed to be determined as having the longest speech time. As illustrated in  FIG. 29C , the cutting portion determining unit  63  determines a cutting portion in which persons from the chairperson C to the participant A are included. In accordance with this, a trimmed image Sac is created. 
     Accordingly, when the chairperson option is set, the chairperson is always displayed. The chairperson is expected to make many important statements, so that the participant that will make important statements can be constantly displayed. 
     &lt;360-Degree-Display Mode&gt; 
       FIG. 30  is a diagram illustrating image data displayed in the 360-degree-display mode according to the embodiment of the present invention. In the 360-degree-display mode, spherical image data obtained when a spherical image is looked down from the zenith is displayed. In accordance with such an image, it is possible to display all participants at a time. In addition, if the following options are not set, image data is disposed such that a direction of 0 degrees in longitude is arranged northward, for example. 
     &lt;&lt;Fixed Chairperson Option&gt;&gt; 
     In the fixed chairperson option, the chairperson is always disposed northward. The screen switching unit  64  of the transmission terminal  10  specifies the chairperson from spherical image data and disposes the chairperson northward. In  FIG. 30 , the participant B is the chairperson. In addition, the direction of the chairperson may be the west, the east, the south, or others. 
     &lt;&lt;Fixed Participant Option&gt;&gt; 
     In the fixed participant option, participants are disposed in a fixed manner. In other words, if the participants are displayed as illustrated in  FIG. 30 , display locations of the participants are not changed. The fixed participant option is different from the fixed chairperson option in that a speaker is emphatically displayed. 
       FIGS. 31A and 31B  are diagrams illustrating the fixed participant option according to the embodiment of the present invention. In  FIG. 31A , the participant A is detected to be a speaker based on a speaker direction. The screen switching unit  64  performs a process to emphasize the participant A on image data. In  FIG. 31A , the participant A is surrounded with an emphasis frame  602 . An emphasis method may employ any technique such as increasing brightness of pixels that include the participant A or increasing contrast. 
     Next, it is assumed that the participant C is detected to be a speaker based on a speaker direction. The screen switching unit  64  performs a process to emphasize the participant C on the image data. In  FIG. 31E , the participant C is surrounded with the emphasis frame  602 . 
     According to the fixed participant option, the user can identify a speaker while all participants are displayed at a time. Further, because screen transition does not occur, an image is preferable for the user. In addition, the screen switching unit  64  can emphasize plural participants at the same time. 
     &lt;&lt;Speaker Emphasis Option&gt;&gt; 
     In the speaker emphasis option, a speaker is always disposed northward. The screen switching unit  64  of the transmission terminal  10  identifies a speaker based on a speaker direction and disposes the speaker northward (the direction may be the west, the east, the south, or others). If another speaker continuously speaks for a switching time, participants to be disposed northward are switched in the same manner as in the single-display mode. 
       FIGS. 32A and 32B  are diagrams illustrating the speaker emphasis option according to the embodiment of the present invention. In  FIG. 32A , the participant C is detected to be a speaker based on a speaker direction. The screen switching unit  64  rotates image data such that the participant C is disposed northward. In  FIG. 32A , the participant C is disposed northward. 
     Next, the participant F is assumed to continuously speak for the switching time. The screen switching unit  64  rotates the image data such that the participant F is disposed northward. In  FIG. 32B , the participant F is disposed northward. 
     According to the speaker emphasis option, it is possible to dispose the speaker northward, so that the user is likely to identify the speaker. Further, arrangement of participants is not changed until the switching time has elapsed, so that it is possible to prevent frequent changes of the screen. 
     &lt;Processing Procedure&gt; 
     In the following, a procedure for determining the trimmed image  9  by the trimming unit  18  is described. First, a case of the single-display mode is described. 
     &lt;&lt;90-Degree Screen Switching Option in Single-Display Mode&gt;&gt; 
       FIG. 33  is a flowchart illustrating an operation procedure of the trimming unit  18  in the single-display mode according to the embodiment of the present invention. The process in  FIG. 33  starts at a time to determine a cutting portion. 
     The screen switching unit  64  determines whether the 90-degree screen switching option is enabled (step S 10 ). 
     If the 90-degree screen switching option is not enabled (No in step S 10 ), sliding exceeding 90 degrees is possible when trimmed images  9  are switched, so that the screen switching unit  64  performs a sliding process and creates the trimmed image  9  that includes a speaker in a switching destination (step S 20 ). 
     If the 90-degree screen switching option is enabled (Yes in step S 10 ), sliding exceeding 90 degrees is not possible when trimmed images  9  are switched, so that the screen switching unit  64  determines whether the speaker in the switching destination is present in a location within ±90 degrees from a speaker in a switching source (step S 30 ). 
     If a result of the determination in step S 30  is Yes, the screen switching unit  64  performs the sliding process and creates the trimmed image  9  including the speaker in the switching destination (step S 50 ). 
     If the result of the determination in step S 30  is No, the screen switching unit  64  creates the trimmed image  9  including the speaker in the switching destination without performing the sliding process (step S 40 ). 
     In accordance with such a procedure, it is possible to create the trimmed image  9  in a case where the 90-degree screen switching option is enabled. 
     &lt;&lt;Two-Screen Option, 90-Degree Screen Switching Option, and Speed-Change Option in Single-Display Mode&gt;&gt; 
       FIG. 34  is a flowchart illustrating an operation procedure of the trimming unit  18  in the single-display mode according to the embodiment of the present invention. The process in  FIG. 34  starts at a time to determine a cutting portion. 
     The screen switching unit  64  determines whether the two-screen option is enabled (step S 10 ). 
     If the two-screen option is enabled (Yes in step S 10 ), the trimming unit  18  divides image data into halves in the horizontal direction (step S 20 ). Accordingly, two images providing a field of view of 180 degrees in the horizontal direction are created. 
     Next, the screen switching unit  64  determines whether a speaker in a switching destination is present within a screen displaying a speaker in a switching source (step S 30 ). If a result of the determination in step S 30  is No, the process proceeds to step S 90 . 
     If the result of the determination in step S 30  is Yes, the screen switching unit  64  determines whether the speed-change option is enabled (step S 40 ). 
     If a result of the determination in step S 40  is No, the screen switching unit  64  performs a sliding process to the speaker in the switching destination at a constant speed and creates a trimmed image  9  (step S 50 ). 
     If the result of the determination in step S 40  is Yes, the screen switching unit  64  performs the sliding process to the speaker in the switching destination while changing a speed and creates a trimmed image  9  (step S 60 ). Start of movement: low speed, during movement: high speed, and end of movement: low speed. 
     In step S 10 , if the two-screen option is disabled (No in step S 10 ), the screen switching unit  64  determines whether the 90-degree screen switching option is enabled (step S 70 ). 
     If a result of the determination in step S 70  is No, the process proceeds to step S 40 . In other words, whether the speed-change option is enabled is determined. 
     If the result of the determination in step S 70  is Yes, sliding exceeding 90 degrees is not possible when trimmed images  9  are switched, so that the screen switching unit  64  determines whether the speaker in the switching destination is present in a location within ±90 degrees from the speaker in the switching source (step S 80 ). 
     If a result of the determination in step S 80  is Yes, it is possible to perform the sliding process, so that the process proceeds to step S 50 . If the result of the determination in step S 80  is No, it is impossible to perform the sliding process, so that the screen switching unit  64  creates a trimmed image  9  that includes the speaker in the switching destination (step S 90 ). 
     &lt;&lt;Plural-Display Mode&gt;&gt; 
       FIG. 35A  is a flowchart illustrating an operation procedure of the trimming unit  18  in the plural-display mode according to the embodiment of the present invention. The process in  FIG. 35A  starts at a time to determine a cutting portion. 
     First, the cutting portion determining unit  63  determines whether a distance between two persons is 180 degrees or more in a predetermined direction (step S 10 ). The two persons refer to the leftmost person and the rightmost person to be included in a single trimmed image  9 . Further, the predetermined direction is determined in advance while the predetermined direction may be either a direction for an increase in longitude or a direction for a decrease in longitude. 
     If a result of the determination in step S 10  is No, the cutting portion determining unit  63  zooms out in the predetermined direction as illustrated in  FIGS. 355 and 35C  (step S 20 ). The trimmed images  9  are switched such that the participant C is included while the participant A and the participant B remain included. 
     If the result of the determination in step S 10  is Yes, the cutting portion determining unit  63  zooms out in a direction opposite to the predetermined direction as illustrated in  FIGS. 35D and 35E  and determines a cutting portion to include both persons within a screen (step S 30 ). The trimmed images  9  are switched such that the participant D is included while the participant A remains included. 
     In accordance with such a process, it is possible to determine a cutting portion such that a field of view is 180 degrees or less in the plural-display mode. 
     &lt;&lt;Determination of Cutting Portion in Plural-Display Mode&gt;&gt; 
     In the single-display mode, a cutting portion may be determined such that the face of one person is included. In contrast, in the plural-display mode, the faces of participants are not necessarily positioned at the same height. Accordingly, it is preferable to determine an appropriate field of view in the latitudinal direction. 
       FIG. 36A  is a flowchart illustrating a procedure for determining a field of view in the latitudinal direction in the plural-display mode according to the embodiment of the present invention. 
     The cutting portion determining unit  63  determines all the faces captured in image data and sets an average value of the faces in the latitudinal direction as a center line  621  (step S 10 ).  FIG. 36B  is a diagram illustrating the center line  621 . A location of the face in the latitudinal direction corresponds to a location of facial components such as the eyes, the nose, and the mouth that are easy to detect. 
     Next, the cutting portion determining unit  63  determines, based on the center line  621  at a center, the field of view in the latitudinal direction such that an aspect ratio is 16:9 (step S 20 ). For example, if a distance between two speakers is 160 degrees, the field of view in the latitudinal direction is 45 degrees from the center line  621  in each of the upper and lower directions.  FIG. 36C  is a diagram illustrating a trimmed image  9  in the plural-display mode according to the embodiment of the present invention. 
     In accordance with such a process, it is possible to create the trimmed image  9  such that the faces of speakers are included in the plural-display mode. 
     Other Applications 
     While the best mode for carrying out the present invention is described using examples, the present invention is not limited at all to these examples. It is possible to add various types of modifications and replacements within the scope of the present invention. 
     For example, the user of the transmission terminal  10   aa  may not select the display mode and the option. A user of another transmission terminal  10   ab  that is participating in a conference may select the display mode and the option instead. If there are plural participants other than the user of the transmission terminal  10   aa , the user of the transmission terminal  10   aa  may authorize a given transmission terminal  10 . 
     Further, the transmission terminal  10   aa  serving as a sender of image data may not create a trimmed image but a transmission terminal serving as a receiver may create the trimmed image. Alternatively, the transmission managing system  50  or the relay device  30  on a network may create the trimmed image. 
     Further, the functional block diagram as illustrated in  FIG. 7  is configured by dividing the transmission managing system  50  and the transmission terminal  10  based on main functions in order to facilitate understanding of processing performed by the transmission managing system  50  and the transmission terminal  10 . The present invention is not limited by how processing units are divided or names thereof. The processing performed by the transmission managing system  50  and the transmission terminal  10  may be divided into more processing units depending on processing contents. Further, processing units may be divided such that one processing unit includes more processes. 
     Further, in the embodiment, the transmission managing system  50  and the relay device  30  are described as separate devices for convenience of description. However, an apparatus in which functions of both devices are integrated may provide the functions of the transmission managing system  50  and the relay device  30 . 
     Further, in the embodiment, the transmission terminal  10  performs communication via the relay device  30 . However, the transmission terminal  10  may perform communication without using the relay device  30 . Web Real-Time Communication (WebRTC) is an example of a communication protocol for such communication. 
     Further, the transmission system  1  may include a plurality of transmission managing systems  50  and the functions of the transmission managing system  50  may be distributed and disposed in a plurality of servers. 
     Further, at least one or more of the databases stored in the storage unit  5000  of the transmission managing system  50  may be present on the communication network  2 . 
     Further, although the display unit  120  is described as an example of a display device, any unit capable of displaying an image such as a projector, a Head-Up Display (HUD), a television receiver, or a car navigation terminal may be employed. 
     In addition, the imaging unit  17  is an example of an imaging unit, the participant detecting unit  61  is an example of a determination unit, the speaker direction estimating unit  14  is an example of a speaker estimating unit, the speech time measuring unit  62  is an example of a measurement unit, and the cutting portion determining unit  63  and the screen switching unit  64  are examples of an acquisition unit. The spherical camera  112   a  is an example of an imaging device. The trimmed image  9  is an example of a speaker image, the trimmed image  9  before switching is an example of a first speaker image, and the trimmed image  9  after switching is an example of a second speaker image. The operation input receiving unit  16  is an example of a selection receiving unit. The switching time is an example of a first threshold and 90 degrees is an example of a second threshold. The transmission and reception unit  11  is an example of a transmission unit and the transmission terminal  10   ab  is an example of an information terminal. 
     According to an embodiment of the present invention, it is possible to provide an information processing apparatus by which frequent changes of a screen is reduced. 
     Further, the present invention is not limited to these embodiments, and various variations and modifications may be made without departing from the scope of the present invention.