PATENT ABSTRACT
A system and method for manipulating images in a videoconferencing session provides users with a 3-D-like view of one or more presented sites, without the need for 3-D equipment. A plurality of cameras may record a room at a transmitting endpoint, and the receiving endpoint may select one of the received video streams based upon a point of view of a conferee at the receiving endpoint. The conferee at the receiving endpoint will thus experience a 3-D-like view of the presented site.

PATENT DESCRIPTION
CROSS REFERENCE TO RELATED APPLICATIONS 
     This Application is a continuation of U.S. application Ser. No. 13/105,290 entitled “Methods and System for Simulated 3D Videoconferencing” filed May 11, 2011, which claims priority to U.S. Provisional Application Ser. No. 61/452,270 filed Mar. 14, 2011, all of which are incorporated by reference in their entirety herein. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the field of communication, and in particular to the field of videoconferencing. 
     BACKGROUND ART 
     Videoconferencing enables individuals located remotely one from the other to conduct a face-to-face meeting. Videoconferencing may be executed by using audio and video telecommunications. A videoconference may be between as few as two sites (point-to-point), or between several sites (multi-point). A conference site may include a single participant (user) or several participants (users). Videoconferencing may also be used to share documents, presentations, information, and the like. 
     Participants may take part in a videoconference via a videoconferencing endpoint (EP), for example. An endpoint (EP) may be a terminal on a network, for example. An endpoint may be capable of providing real-time, two-way, audio/visual/data communication with other terminals and/or with a multipoint control unit (MCU). An endpoint (EP) may provide information/data in different forms, including audio; audio and video; data, audio, and video; etc. The terms “terminal,” “site,” and “endpoint” may be used interchangeably. In the present disclosure, the term endpoint may be used as a representative term for above group. 
     An endpoint may comprise a display unit (screen), upon which video images from one or more remote sites may be displayed. Example endpoints include POLYCOM® VSX® and HDX® series endpoints, each available from Polycom, Inc. (POLYCOM, VSX, and HDX are registered trademarks of Polycom, Inc.) A videoconferencing endpoint may send audio, video, and/or data from a local site to one or more remote sites, and display video and/or data received from the remote site(s) on its screen (display unit). 
     Video images displayed on a screen at an endpoint may be displayed in an arranged layout. A layout may include one or more segments for displaying video images. A segment may be a predefined portion of a screen of a receiving endpoint that may be allocated to a video image received from one of the sites participating in the videoconferencing session. In a videoconference between two participants, a segment may cover the entire display area of the screens of the endpoints. In each site, the segment may display the video image received from the other site. 
     An example of a video display mode in a videoconference between a local site and multiple remote sites may be a switching mode. A switching mode may be such that video/data from only one of the remote sites is displayed on the local site&#39;s screen at a time. The displayed video may be switched to video received from another site depending on the dynamics of the conference. 
     In contrast to the switching mode, in a continuous presence (CP) conference, a conferee (participant) at a local endpoint may simultaneously observe several other conferees from different endpoints participating in the videoconference. Each site may be displayed in a different segment of the layout, which is displayed on the local screen. The segments may be the same size or of different sizes. The combinations of the sites displayed on a screen and their association to the segments of the layout may vary among the different sites that participate in the same session. Furthermore, in a continuous presence layout, a received video image from a site may be scaled, up or down, and/or cropped in order to fit its allocated segment size. It should be noted that the terms “conferee,” “user,” and “participant” may be used interchangeably. In the present disclosure, the term conferee may be used as a representative term for above group. 
     An MCU may be used to manage a videoconference. An MCU is a conference controlling entity that is typically located in a node of a network or in a terminal that receives several channels from endpoints and, according to certain criteria, processes audio and/or visual signals and distributes them to a set of connected channels. 
     Exemplary MCUs include the MGC-100 and RMX 2000®, available from Polycom Inc. (RMX 2000 is a registered trademark of Polycom, Inc.). Some MCUs may be composed of two logical units: a media controller (MC) and a media processor (MP). A more thorough definition of an endpoint and an MCU may be found in the International Telecommunication Union (“ITU”) standards, including the H.320, H.324, and H.323 standards. Additional information regarding the ITU standards may be found at the ITU website www.itu.int. 
     In a CP videoconferencing session, the association between sites and segments may be dynamically changed according to the activities taking part in the conference. In some layouts, one of the segments may be allocated to a current speaker, for example. The other segments of that layout may be allocated to other sites that were selected as presented sites or presented conferees. A current speaker may be selected according to certain criteria, including having the highest audio signal strength during a certain percentage of a monitoring period. The other presented sites, may include the image of the conferee that was the previous speaker; the sites having audio energy above a certain thresholds; certain conferees required by management decisions to be visible; etc. 
     In a conventional CP videoconference, each layout is associated with a video output port of an MCU. A conventional video output port may comprise a CP image builder and an encoder. A conventional CP image builder may obtain decoded video images of each one of the presented sites. The CP image builder may scale and/or crop the decoded video images to a required size of a segment in which the image will be presented. The CP image builder may further write the scaled image in a CP frame memory in a location that is associated with the location of the segment in the layout. When the CP frame memory is completed with all the presented images located in their associated segments, the CP image may be read from the CP frame memory by the encoder. 
     The encoder may encode the CP image. The encoded and/or compressed CP video image may be sent toward the endpoint of the relevant conferee. A frame memory module may employ two or more frame memories, for example, a currently encoded frame memory and a next frame memory. The memory module may alternately store and output video of consecutive frames. Conventional output ports of an MCU are well known in the art and are described in a plurality of patents and patent applications. A reader who wishes to learn more about a conventional output port is invited to read U.S. Pat. No. 6,300,973, for example, the content of which is incorporated herein by reference in its entirety. 
     A user&#39;s experience of videoconference is typically limited to one or more high-resolution two-dimensional displays. Although 3D (3-dimension) technologies have become more and more popular in other different fields, such as movies, media entertainment, etc., obstacles have prevented the 3D technology from being implemented by the videoconference industry. These obstacles include the need to wear special 3D glasses and the use of expensive cameras and displays. Creation of holograms may require special screens, cameras, and hardware that are very expensive, etc. Therefore, it is not realistic to expect conventional videoconferencing users to pay such high costs. Nor is it realistic to expect conventional videoconferencing users to sit in a videoconference wearing 3D glasses, which would be visible to other conferees. 
     Furthermore, many companies have invested in a conventional 2D video conferencing infrastructure. Those companies would like to keep their capital investment in their current video conferencing infrastructure that does not support current existing 3D video conferencing techniques. 
     The above-described deficiencies in videoconferencing do not limit the scope of the inventive concepts of the present disclosure in any manner. The deficiencies are presented for illustration only. 
     SUMMARY OF INVENTION 
     The below disclosed embodiments provide a novel system and method for manipulating a video image in videoconference such that a user may experience a 3D-like view of one or more presented sites. The disclosed exemplary embodiments do not require 3D cameras, 3D screens, 3D glasses, or hologram display hardware. On the contrary, the disclosed embodiments may utilize conventional 2D video cameras and conventional 2D video screens to create a 3D-like view of one or more presented sites. 
     In one embodiment, a transmitting endpoint in a site may comprise two or more video cameras, each of which may record the room of the site from a different angle. The transmitting endpoint may encode each video image and send the encoded streams to an MCU. 
     At the MCU, each of the received video streams from a plurality of conferees is transferred toward an associated input video port. In addition to the conventional components of an input video port, an input video port may comprise a conferee-point-of-view detector (CPOVD). The CPOVD may detect the angle at which the conferee looks at the screen and at which region of the screen the conferee is looking. The CPOVD may send the detected information toward a controller of the MCU. 
     As long as the video image of a transmitting endpoint, which has two or more cameras, is embedded in the video image that is sent toward one or more receiving endpoints, the controller may periodically sample the stored information regarding the received conferee&#39;s point-of-view direction. Once a change in the viewer&#39;s point of view has been detected, the controller may determine whether to continue using the video streams from the currently chosen camera, to select a video stream received from another camera of that transmitting endpoint, etc. 
     The viewer, in the receiving endpoint, will experience a 3D-like view of the presented sites. This experience may be affected by the number and location of the cameras in the transmitting endpoint. To enhance the experience, more cameras may be placed and along an arc wherein the center of the arc is located near to or on the centerline of the display at the transmitting site. Furthermore, the accuracy of the viewer-point-of-view detector may also affect the experience of the user. 
     Other different techniques may be used to enhance the viewer&#39;s experience. Exemplary techniques include using a “sliding window,” for example. The sliding window imitates the effect of controlling the far end camera such as move left, right, up and down. In some embodiments, the movement of the receiving conferee&#39;s gaze may be used as a remote camera panning left or right, tilting up or down or zooming in or out. In some embodiments, the video received from the remote location may be cropped to a window that is presented on screen and slides along the video image. For example, if the conferee gaze detector indicates that the gaze of the conferee points at the most left side of the screen, the effect on the screen may resemble a panning left of the remote camera, although in this embodiment only the presented window is sliding to the left and the remote camera is not panning left. Once the conferee point of view is locked on the area in which the conferee is interested, the window may slide until it will eventually stop. In the above embodiment, the stopping point may be the point in which the conferee is staring to the center of the conferee&#39;s screen. 
     The present disclosure is not limited to providing a 3D-like view of only one site. One or more sites may comprise a plurality of cameras. The number of segments displayed in a layout on a conferee screen as well as the conferee&#39;s screen size may affect the 3D-like experience. 
     These and other aspects of the disclosure will be apparent in view of the attached figures and detailed description. The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present invention, and other features and advantages of the present invention will become apparent upon reading the following detailed description of the embodiments with the accompanying drawings and appended claims. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of apparatus and methods consistent with the present invention and, together with the detailed description, serve to explain advantages and principles consistent with the invention. In the drawings, 
         FIG. 1  is a block diagram illustrating relevant elements of a portion of a multimedia multipoint videoconferencing system according to one embodiment. 
         FIGS. 2 a -2 c    illustrate different instances during a video conferencing session, in which a conferee has different viewpoint in each instance. 
         FIG. 3  is a block diagram illustrating relevant elements of portions of a transmitting site according to one embodiment. 
         FIG. 4  is a block diagram illustrating relevant elements of an exemplary MCU, according to one embodiment. 
         FIG. 5  is a flowchart illustrating relevant actions of a process for selecting a camera based on conferee point of view, according to one embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without these specific details. In other instances, structure and devices are shown in block diagram form in order to avoid obscuring the invention. References to numbers without subscripts or suffixes are understood to reference all instance of subscripts and suffixes corresponding to the referenced number. Moreover, the language used in this disclosure has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter, resort to the claims being necessary to determine such inventive subject matter. Reference in the specification to “one embodiment” or to “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiments is included in at least one embodiment of the invention, and multiple references to “one embodiment” or “an embodiment” should not be understood as necessarily all referring to the same embodiment. 
     Although some of the following description is written in terms that relate to software or firmware, embodiments may implement the features and functionality described herein in software, firmware, or hardware as desired, including any combination of software, firmware, and hardware. In the following description, the words “unit,” “element,” “module” and “logical module” may be used interchangeably. Anything designated as a unit or module may be a stand-alone unit or a specialized or integrated module. A unit or a module may be modular or have modular aspects allowing it to be easily removed and replaced with another similar unit or module. Each unit or module may be any one of, or any combination of, software, hardware, and/or firmware, ultimately resulting in one or more processors programmed to execute the functionality ascribed to the unit or module. Additionally, multiple modules of the same or different types may be implemented by a single processor. Software of a logical module may be embodied on a computer readable medium such as a read/write hard disc, CDROM, Flash memory, ROM, or other memory or storage, etc. In order to execute a certain task a software program may be loaded to an appropriate processor as needed. 
     In the description and claims of the present disclosure, “comprise,” “include,” “have,” and conjugates thereof are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements, or parts of the subject or subjects of the verb. 
       FIG. 1  illustrates elements of an exemplary multimedia multipoint conferencing system  100  according to one embodiment. System  100  may include a network  110 , one or more multipoint control units (MCU)  120 , and a plurality of endpoints in different sites  130   a - n . Network  110  may be a packet switched network, a circuit switched network or any combination of the two, for example. The multimedia communication over the network may be based on a communication protocol, including H.320, H.323, SIP, etc. 
     MCU  120  and endpoints  130   a - n  may be adapted to operate according to various embodiments to improve the experience of a conferee looking at a CP video image of a multipoint video conference. In embodiments implementing a centralized architecture, MCU  120  may be adapted to perform the automatic display adaptation methods described herein. Alternatively, in a distributed architecture, endpoints  130   a - n  with MCU  120  may be adapted to perform the automatic display adaptation methods. More information about the operation of MCU  120  and endpoints  130   a - n  according to various embodiments is disclosed below. 
       FIGS. 2 a -2 c    illustrate different instances during a video conferencing session in which a conferee  204  has a different viewpoint in each instance. In  FIG. 2 a   , conferee  204  looks at the center along the perpendicular  210  of the two-dimensional screen  202  of the conferee&#39;s EP. In  FIG. 2 b   , the head of conferee  204  is rotated to the right side of the screen  202  and creates an angle  216  of +A degrees between the face (the nose) of the conferee and the perpendicular  210  to the screen. In  FIG. 2 c   , the head of conferee  204  is rotated to the left side of the screen  202  and creates an angle  216  of −a degrees between the face (the nose) of the conferee and the perpendicular  210  to the screen. 
       FIG. 3  illustrates a block diagram with relevant elements of portions of a transmitting site  300  according to one embodiment. Transmitting site  300  may be a meeting room having a table  310 , a plurality of chairs  312 , and a videoconferencing endpoint  330  having a plurality of video cameras  320 ,  322 , and  324 . The plurality of cameras may be located in a horizontal plane above the screen of the EP  330  along a virtual arc. Each camera captures the table  310  and the conferees along the table from a different angle simulating a different head position of a conferee that receives a video stream from the meeting room  300 . Each of the video cameras  320 ,  322 , and  324  creates and delivers a stream of video images to the endpoint  330 . The endpoint  330  compresses the three video streams and sends the compressed video streams toward an MCU  120  that conducts the video conferencing session. Compressing the three video streams may be done in a single encoder that complies with the compression standard H.264 MVC, for example. Other endpoints may use three separate encoders and may send three separate compressed video streams, one for each of cameras  320 ,  322 , and  324 . 
       FIG. 4  illustrates an MCU  400 , which is capable of dynamically and automatically switching between a plurality of streams of video images. The plurality of streams received from a plurality of video cameras  320 ,  322 , and  324  associated with an EP  330  located in a first site  300 . The switching at the MCU  400  may be done based on the gaze of an observer, located in a second site and receives the selected video image sent from the first site via the MCU  400 . MCU  400  may comprise a network interface module (NI)  420 , an audio module  430 , a control module (CM)  440  and a video module  450 . The control module  440  may further comprise a camera selector controller (CSC)  442 . The network interface module  420  may receive communication from a plurality of endpoints  130   a - n  via network  110 . Network interface  420  may process the communication according to one or more communication standards, including H.320, H.323, SIP, etc. Network interface  420  may also process the communication according to one or more compression standards, including H.261, H.263, H.264, H.264 MVC, G.711, G.722, MPEG, etc. In addition, network interface  420  may receive and transmit control and data information to/from other MCUs and endpoints. More information concerning the communication between endpoint and the MCU over network  110  and information describing signaling, control, compression, and setting a video call may be found in the international telecommunication union (ITU) standards H.320, H.321, H.323, H.261, H.263, H.264, G.711, G.722, and MPEG etc. 
     Network interface module  420  may multiplex/de-multiplex the different signals, media and/or “signaling and control” that are communicated between the endpoints and the MCU. The compressed audio signals may be transferred to and from the audio module  430 . The compressed video signals may be transferred to and from the video module  450 . The “control and signaling” signals may be transferred to and from control module  440 . Furthermore, if a distributed architecture is used, network interface module  420  may be capable of handling automatic and dynamic gaze related information that is transferred from the endpoints  130   a - n  toward the control module  440 . 
     In one distributed architecture embodiment the automatic and dynamic gaze detection information is sent from an EP  130  to MCU  400 . The gaze detection information may be sent from the EP  130  as a part of a predefined header of an RTP (Real-Transport Protocol) packet. NI  420  may be adapted to process the predefine header and to transfer the gaze detection information to the CM  440 . The gaze detection information may include the angle ±a ( 216 ,  218 ) of the nose of the conferee from the perpendicular  210 . In another embodiment, the information about the gaze of the conferee may be expresses by the location of the conferee&#39;s nose, in pixels (W;H) along the width ‘W’ axis, and height ‘H’ axis of the video image received from that conferee&#39;s EP, for example. In some embodiments, the gaze may be expressed in number of pixels in pixels (W;H) from the top left corner of the image. 
     In yet another distributed architecture embodiment, the EP may send information regarding the gaze of its conferee over the audio signal using dual-tone multi-frequency signaling (DTMF). In such an embodiment, the NI  420  processes the received signals and sends the compressed audio, carrying the DTMF signal toward the audio module  430 . The audio module  430  decompresses the audio signal, decodes the DTMF information, and transfers the Gaze information toward the CM  440 . In yet another distributed architecture embodiment, the EP  130  may send information regarding the gaze of its conferee via out of band connection. The out of band connection may be carried over an Internet Protocol (IP) network, for example. In such embodiment, the NI  420  may process the received IP packets, carried over an IP connection and sends the Gaze information toward the CM  440 . 
     Audio module  430  may receive, via network interface  420  compressed audio streams from the plurality of endpoint  130   a - n . The audio module  430  may decode the compressed audio streams, analyze the decoded streams, select certain streams, and mix the selected streams. The mixed stream may be compressed and the compressed audio stream may be sent to the network interface  420 , which sends the compressed audio streams to the different endpoints  130   a - n . Audio streams that are sent to different endpoints may be different. For example, the audio stream may be formatted according to a different communication standard and according to the needs of the individual endpoint. The Audio stream may not include the voice of the user associated with the endpoint to which the audio stream is sent. However, the voice of this user may be included in all other audio streams. 
     In some embodiments, the audio module  430  may be adapted to analyze the decoded audio signals received from the endpoints, and decodes the DTMF signals for retrieving information regarding the gaze of the conferee&#39;s whose audio signal was processed. The gaze information may be transferred to the control module  440 . In some embodiments, two or more microphones may be used in a certain site. 
     Video module  450  may receive compressed video streams from the plurality of endpoints  130   a - n , which are sent toward the MCU  400  via network  110  and processed by network interface (NI)  420 . Video module  450  may create one or more compressed CP video images according to one or more layouts that are associated with one or more conferences currently being conducted by the MCU  400 . A video module  450  may have a plurality of input modules  451   a - c , a plurality of output modules  455   a - c  and a video common interface  454 . Each input module  451   a - c  may be associated with an endpoint. Each output module  455   a - c  may be associated with one or more endpoints. 
     Input module  451   a - c  may include among other elements a decoder  452  and a Conferee&#39;s-Point-of-View Detector (CPOVD)  453 . CPOVD  453  may be a sub-module of input modules  451   a - c , or in an alternate embodiment, CPOVD  453  may be a sub-module of video module  450 . An input module  451   a - c  may be associated with an endpoint and may process a plurality streams of compressed video images received from plurality of video cameras  320 - 324  that are connected to the associated endpoint  330 . The decoder  452  may receive the plurality of compressed video streams, which may comprise three streams for example, from an associated endpoint and decode the compressed video stream according the compression standard H.264 MVC into three decoded video data images, each decoded image received from one of the three cameras. The ITU H264 MVC standard is a multi-view-video-coding standard, which enables the transmitting endpoint to broadcast multiple video streams from the two or more cameras. Each decoded image may be stored in a decoder frame memory from which it is transferred toward one or more output modules  455   a - c  via common interface  454 . The common interface  454  may be a TDM bus, packet based bus (such as an ATM bus, IP bus), serial bus, parallel bus, connection switching, shared memory, direct connection, or any variety of these. 
     In an alternate embodiment in which H.264 MVC is not used, an input module may be associated with one of the cameras  320 - 324  of its associated endpoint  330 . Thus, endpoint  330  may be associated with three input modules  451 . 
     The MCU receives from a plurality of endpoints a plurality of compressed video streams. Some of the endpoints may send compressed video streams received from its two or more video cameras using the ITU H.264 MVC standard, while other endpoints may send a compressed video stream received from a single video camera. 
     In one embodiment, each of the endpoints  330  may comprise a CPOVD  453  that receives the video input data from an endpoint camera, processes the received data, and defines the direction in which the conferee is looking. The conferee point of view information may then be sent to the MCU from the endpoint. The information may be sent in-band, in association with the compressed video stream, as part of a packet&#39;s headers. Alternatively, the information may be sent out of band over a separate connection between the endpoint and the MCU, over an Internet Protocol (IP) connection, for example. 
     In one embodiment, the decoded data stored in the frame memory, which is associated with the central camera  322  may be sampled by the CPOVD  453 . CPOVD  453  may be adapted to analyze the video image received from the central camera and to detect the gaze of the conferee that uses the associated EP  330 . A CPOVD  453  may process the decoded image; identify the nose of the conferee; and determine the location of the nose compared to the perpendicular  210  to the screen, or the center of the screen. Detecting the nose may be implemented by an image-processing algorithm that identifies the two eyes and the nose in the center. In a site that has only one camera, the images from the single camera are processed instead of the video of the central camera. 
     In some embodiments of an MCU  400 , a central CPOVD  453  may be used. Such a central CPOVD  453  may obtain the decoded video from each one of the input video ports, in parallel or in serial. Such a CPOVD  453  may process the obtained decoded video and determine the gaze angle of the conferee. The detected gaze angle may be used for selecting the appropriate camera. 
     In one embodiment, an MCU  400  may use a learning period for learning the properties of an organ of the conferee&#39;s face, such as a nose, an eye (left, right or both), etc. the term nose may be used as a representative term for such an organ. In addition for learning the area around the nose, the CPOVD  453  may learn the topology of the gaze (represented by the nose, for example) in relation to the video image received from the center camera and the screen of the endpoint. The learning period may begin upon receiving a request from a conferee to join the conference. During the learning period, the MCU  400  may present the self-image of the conferee, which is received from the center camera, over the entire screen of the conferee&#39;s endpoint. In addition to the self image, the MCU  400  may present above the self image three points (colored area, a circles, for example) along a virtual horizontal line starting from left to right in the middle of the height of the screen. In other embodiment, five points may be presented on the screen, one in the center of the screen, and one at the center of each quarter of the screen (i.e., the center of the top left quarter, the center of the top right quarter, the center of the bottom left and the center of the bottom right quarter). 
     The MCU  400 , by using an interactive-video-control-human interface may place a cursor on the screen and prompt the conferee to look at the center point on the screen and to place the cursor on the conferee&#39;s nose. Prompting the conferee may be done by an Interactive Voice Response (IVR) or by presenting text instructions over the screen. After clicking on the cursor, the MCU  400  may collect information on the location of the nose and the properties in a certain area around the nose while the conferee looks at the center point. The process may be repeated for each of the colored points. In some embodiments, two or more points may be used in each side of the screen. The interactive-video-control-human interface is disclosed in U.S. Pat. No. 7,542,068, the content of which is Incorporated herein by reference in its entirety. At this point of time the CPOVD  453  has information on the location (in pixels from the top left corner of the image) of the conferee&#39;s nose in the video image received from the conferee&#39;s center camera  322  when the conferee looks at the center of the screen and at the center of each quarter of the screen. In addition, the CPOVD  453  has information on the properties of the area around the nose in each position. This information may be processed for use as filters to define the gaze of the conferee during the video session. 
     In yet another embodiment, the CPOVD  453  may implement a gaze detector. Gaze detection methods are well known in the art of image processing. There are a plurality of articles that describe different method of gaze detection. Some of them use a wearable device such as magnetic elements, RF receivers, and or transmitters, etc., others uses a dedicated camera for tracking and capturing the user&#39;s eyes, others just run image processing algorithms that identify the user&#39;s gaze, etc. a CPOVD  453  may use a commercial gaze detector. Example commercial gaze detection systems include SMI RED systems RED, RED 250, and RED 500, manufactured by SensoMotoric Instruments GmbH (SMI) from Teltow Germany. Other gaze detection systems use the red-eye effect by using a near infrared lighting source. Gaze detection techniques are known to the art and will not be further discussed herein. 
     Various embodiments may implement different techniques of gaze detection. Some embodiments may use near infrared (NIR) lighting and analyzing the received video image looking for the red-eye effect on the image. Other embodiments may implement image-processing methods looking for changes in the gaze direction. The information about the current gaze direction of the conferee in a receiving endpoint, or changes in the gaze directions may be utilized for controlling the video image received from a transmitting endpoint such that the transmitted image is adapted to the gaze of the receiving endpoint. 
     In some embodiments, if two or more conferees share the same site and the same endpoint, one of them may be selected as the one to whom the gaze detector will respond. The selection of the conferee may be done automatically in one embodiment. The selection criteria that may be used may include the conferee that sits in the head of the table, the conferee that sits in the center of the group of conferees, the conferee that sits closest to the camera, etc. In other embodiments, the conferee may be selected manually during the beginning of the conference session, for example when in the learning mode. 
     From time to time, periodically, and/or upon receiving a command from the CSC  442 , the CPOVD  453  may sample a captured frame of the decoded video. The CPOVD may analyze the sampled image and identify the direction of the conferee&#39;s gaze. The CPOVD  453  may output the gaze detected information to the CSC  442  via control line  444 . 
     The received conferee&#39;s point of view information may be stored at the MCU controller. This information may be used for controlling a video output port that has been assigned to that received conferee. When the MCU controller determines that video image received from a transmitting endpoint having two or more cameras is to be transmitted toward the endpoint of the received conferee, then the information regarding the received conferee&#39;s point of view may be used for selecting an appropriate video stream of the video streams received from the two or more video cameras of the transmitting endpoint. 
     In some embodiments, the CPOVD  453  may deliver parameters according to the location of the nose. The nose represents the center of the gaze of the conferee. The location may be in pixels. In some embodiments of the video module  450 , a single CPOVD  453  may be used. Such a CPOVD  453  may be a separate module external to the input module  451   a - c . In such embodiment, the CPOVD  453  may obtain from the common interface  454  a decoded video frame received from one of the input modules  451   a - c , process it, and deliver gaze information to the CSC  442 . Then, the CPOVD  453  may obtain decoded frame received from a next input module  451   a - c , process it, deliver gaze information and may continue to the following input module, looping repeatedly. In a distributed architecture, a CPOVD  453  may be located in an endpoint  330  and may process the video data generated by its central video camera  322 . More information about the operation of a CPOVD  453  is discussed below in conjunction with  FIG. 5 . 
     Among other elements, an exemplary output module  455   a - c  may include an editor  456  and an encoder  458 . Editor  456  may get decoded data of selected video images from the common interface  454  to be composed into a CP image created by the output module  455 . The editor  456  may scale, crop, and place the video data of each conferee into an editor frame memory according to the location and the size of the image in the layout associated with the composed video of the CP image. Editor  456  and encoder  458  may each be considered as modules, or as sub-modules of output modules  455   a - c.    
     When the editor frame memory is ready with all the selected conferee&#39;s images, the data in the frame memory is ready to be encoded by encoder  458  and sent toward its associated endpoint. The editor  456  may be configured to collect the decoded video images received from a plurality of endpoints (video input modules  451   a - c ), to build the frames of the CP video images based on layout instructions received from the CM  440  regarding each video image, and send the composed CP video image toward a display unit of the endpoint. 
     Depending on the current layout that is transmitted toward the received conferee, the conferee&#39;s video output port may arrange the selected video stream in a segment of a CP video image or as a switching video image and send it toward the receiving endpoint. In some embodiments, the 3D imitation may be limited to images that are displayed in a segment bigger than a certain size, a quarter of a screen for example. 
     Additional functions that may be included in the video module  450  are described in U.S. patent application Ser. No. 10/144,561; U.S. Pat. No. 6,100,973; and International App. Serial No. PCT/IL01/00757, the contents of which are incorporated herein by reference. In a distributed architecture, an endpoint may include an editor  456 . In such embodiment, the editor  456  may be located after a decoder of the endpoint. 
     In addition to the operation of an editor  456  in an output module, editor  456  may be able to adapt the video image presented in at least one segment of the CP video image to the gaze of the conferee that is associated with that editor  456  and receives that CP video image. This conferee is referred to as the receiving conferee. An exemplary embodiment of an editor  456  may adapt the video image in the current speaker segment to the gaze of the receiving conferee looking at the speaker image in the CP video image. To do so, the editor  456  may obtain from CSC  442  information about which one of the three video cameras  320 - 324  of the endpoint of the current speaker fits the gaze of the receiving conferee. During a transition from one camera to another camera of the same endpoint, different techniques may be used to overcome transition digital artifacts caused by the difference between the positions of the cameras, including morphing techniques for smoothing the transition. The morphing technique may provide a perception of a smooth transition. Morphing techniques are well known in the video processing arts and have been used for more than twenty years. Other techniques that may be used include fading-in effects, fading-out effects, etc. 
     Furthermore, in order to avoid jumping from one camera to the other and vice versa, an embodiment may have an overlap between two adjacent cameras and may use hysteresis in the decision thresholds for selecting a camera based on the receiving conferee&#39;s point of view. Consequently, the changing point from a right camera to a left camera may be other than the changing point from the left camera to the right one. 
     In addition, some embodiments after changing the selected camera, a time delay may be implemented for a certain period, for example a few seconds, in which the selected video camera is not changed again. 
     Control module  440  may be a logical unit that controls the operation of the MCU  400  and conducts the conference session. In addition to conventional operation of a typical MCU, MCU  400  according to various embodiments may be capable of additional functionality as result of having the control module  440 . Control module  440  may include a Camera-Selector Controller (CSC)  442 . In one embodiment, a CSC  442  may control a plurality of video output modules  455   a - c . In other embodiments, each of a plurality of CSC  442  controls an output module  455   a - c . Per each output module  455 , a CSC  442  may receive gaze information of the conferee associated with the EP that is associated with that output module  455 . The gaze information may include the view angle ±a  216 ,  218  of the conferee from the perpendicular  210  to the conferee&#39;s screen. In other embodiments, the gaze information may be the coordinates (W;H, Width; Height) of the nose of the conferees in pixels along the width axis (W) and the height (H) axis of the conferee&#39;s self image received from the center camera  322  of the conferee&#39;s EP  330 , etc. 
     In other embodiments, an MCU for media relay video conferencing (a media relay MCU or MRM) may use a distributed architecture as described herein. In such an architecture, the endpoints  330  may comprise the gaze detector and the editor. The gaze detector may process the video image received from one of the cameras  320 ,  322 , and  324  of the endpoint  330  to define the gaze of the conferee and transfer the gaze information toward the CSC  442  that is located in the MRM. The editor may select one of the decoded streams from the endpoint decoder  452  that were received from a transmitting endpoint to which the gaze of the conferee pointed, according to instructions obtained from the CSC  442 , and embed the selected stream in a CP video image that may be presented on the endpoint display unit. A reader who wishes to learn more about media relay video conferencing and MRM is invited to read US Patent Application Publication No. 2010/0194847, the content of which is incorporated herein by reference. 
     After collecting the information on the conferee&#39;s gaze and the layout that is currently presented to that conferee, the CSC  442  may determine the segment at which the conferee is looking. Then, CSC  442  may determine which camera ( 320 ,  322 , or  324 ) of the endpoint  330  that is associated with this segment matches the direction of the conferee&#39;s gaze. If the conferee looks to the left side of the segment, then camera  320  may be selected. If the conferee looks to the right side of the segment, then camera  324  may be selected, and if to the center of the segment then camera  322  may be selected. Information on the selected camera may be transferred to the editor  456  of the output module  455  that is assigned to that conferee. The information may include information how to obtain the decoded data from the common interface  454  and instead of each stream to place this image in the CP video image. More information on CSC is disclosed below in conjunction with  FIG. 5 . 
     In some embodiments, a single CSC  442  may control a plurality of editors  456 . In other embodiments, a plurality of CSCs  442  each control one of the plurality of editors  456 . The CSC  442  may calculate the scaling, cropping, and movement when moving from one camera to another. 
     Based on this information, the editor  456  starts the replacing process. In some embodiments, replacing images from two different cameras in the same room may take few frames in order to smooth the transition. An exemplary embodiment may use a fading technique in which the old image is faded while the image from the selected camera is increased. Other embodiment may use a morphing technique to provide a perception of a smooth transition, etc. 
       FIG. 5  is a flowchart illustrating relevant actions of process  500 . Process  500  may be implemented by a CPOVD  453  for defining the gaze of the conferee that is associated with that CPOVD  453  and selecting a camera, in a second room, based on the conferee&#39;s s point of view. In this embodiment, the conferee resides at a first site, and is referred as a first conferee, while the cameras ( 320 ,  322 , and  324 ) are located at a second site  300 . In one embodiment, process  500  may change cameras only if the first conferee looks at the segment of the current speaker. Other embodiments may switch between cameras even if the first conferee looks at a segment other than the segment of current speaker in the CP video image. 
     The process may be initiated in block  502  by CSC  442  when the first conferee joins the conference. Upon initiation in block  502 , a learning period may be executed by the CPU of the CPOVD in block  504 . During the learning period in block  504 , the CPOVD  453  may learn the topology of the first site as it is reflected in a video image received from a camera in the first site. The camera may be the center camera if the endpoint in the first room has three cameras; otherwise, where only one camera exists at the first site, the camera may be the only camera used in the first site. Learning the topology may include identifying the location of the first conferee in the self-image, associating the gaze as it is expressed on the image with a location on the screen on which the conferee looks, etc. Learning the topology may be done automatically by prompting the conferee to look at a different location on the screen and determining the conferee&#39;s gaze at each time. In some embodiments, learning the topology may be performed semi-automatically, where the conferee is requested to look on a certain location on the screen and to point with a cursor on an organ on the image of the conferee&#39;s face, putting the cursor on an eye, the nose, etc. 
     At the end of the learning period, a decision may be made in block  510  whether the conference is running. The conference may be considered as running when the video image presented over the screen of the first endpoint is received from at least one other site. If not running, process  500  waits until the conference begins to run. If in block  510  the conference is running, then information on the current presented layout on the first screen is obtained in block  512  from CSC  442 . The information may include the coordinates of the top left and bottom right of each segment, the coordinates, in pixels (Wc;Hc), of the center of each segment, the number of cameras in the site of that segment, etc. The CPOVD  453 , which is associated with the input module  451  that is assigned to the first endpoint, may obtain a decoded video stream that was received from the center camera of the first endpoint in order to detect in block  512  the gaze of the first conferee. 
     Detecting the gaze may be done by one or more of the techniques that are described above. The gazing point on the screen of the first endpoint may be expressed in pixels (Wg;Hg) from the top left corner of the screen. Based on the coordinates of the gazing point (Wg;Hg) on the screen of the first endpoint and the obtained information on the layout present on that screen, process  500  may determine in block  512  the segment at which the first conferee is looking Based on the information obtained on that segment in block  504 , a decision is made in block  520  whether the remote site (the site that is presented in that observed segment) has a single camera. If so, process  500  waits in block  540  for a predetermined period of time. The predetermined period of time may be a configurable period between few tens of milliseconds to few seconds, for example. After the waiting period of block  540  process  500  returns to block  512  and starts a new cycle of adapting the presented image to the gaze of the conferee. 
     If in block  520  the remote site has more than one camera, then process  500  proceeds to block  522  in which the CPOVD  453  determines, based on the detected coordinates (Wg;Hg) of the first conferee&#39;s gaze and the coordinates of the center of the relevant segment (Wc;Hc), whether the first conferee looks at the center of the segment, the left side, or the right side of the segment. In one embodiment, the decision may be made by using two values as thresholds A1 and A2 wherein the absolute value of A2 is larger than A1. The values of A1 and A2 may depend on the size of the segment, where the bigger the segment the bigger the values of A1 and A2. 
     In order to determine in block  522  whether the first conferee looks at the center of the segment, a CPOVD  453  may calculate the value of (Wc−Wg). If the absolute value is smaller than A1, then CPOVD  453  may decide that the first conferee looks at the center of the segment. Thus, the current selected camera in the remote site is the center camera  322 . To determine whether the first conferee looks at the left side of the segment, CPOVD  453  may check if Wg&lt;(Wc−A2). If so, then CPOVD  453  may decide that the first conferee looks at the left side of the segment and the right camera  324  may be selected to match the gaze. In order to determine whether the first conferee looks at the right side of the segment, CPOVD  453  may check if Wg&gt;(Wc+A2). If so, then CPOVD  453  may decide that the first conferee looks at the right side of the segment. Thus, the current selected camera in the remote site is the left camera  324 . 
     The CPOVD  453  may then determine whether there is a need to switch from the previous selected camera to the current selected camera. If in block  530  the previous selected camera is the same as the current selected camera, then there is no need to switch cameras and process  500  continues to block  540 . The decisions may be established according to various predetermined criteria, including a predefined change in the angle of the viewer&#39;s point of view, a predefined angle from which a certain camera&#39;s input is to be chosen; etc. If there is a need to switch cameras, then an instruction may be sent in block  532  to the editor module  456  to start the transition from the video stream received from the previous selected camera to the video stream received from the current selected camera. The instruction may be sent via the CSC  442 . After instructing the editor  456 , process  500  may wait in block  540  before starting a new cycle from block  512 . 
     In one embodiment of method  500 , block  522  may further consider whether the video image of the transmitting endpoint was cropped along the width axis before being placed in the segment of the CP layout. If it was, the CSC  442  may check if the cropping area can be slightly moved in the direction that leads the Wg toward the Wc of the segment. Only after sliding the cropped image under the segment, CPOVD  453  may then determine whether there is a need to switch from the previous selected stream (camera) of the transmitting endpoint to the current selected stream (camera of the transmitting endpoint). 
     Although the description above is written in terms of selecting a camera, one skilled in the art will recognize that a selection of a camera may be accomplished by selecting a video stream that is generated by the camera. Therefore, the terms selecting a video stream and selecting a camera may be considered as interchangeable terms. 
     It is to be understood that the above description is intended to be illustrative, and not restrictive. The above-described apparatus, systems, and methods may be varied in many ways, including, changing the order of steps, and the exact implementation used. The described embodiments include different features, not all of which are required in all embodiments of the present disclosure. Moreover, some embodiments of the present disclosure use only some of the features or possible combinations of the features. Different combinations of features noted in the described embodiments will occur to a person skilled in the art. Furthermore, some embodiments of the present disclosure may be implemented by combination of features and elements that have been described in association to different exemplary embodiments along the discloser. The scope of the invention is limited only by the following claims and equivalents thereof.