Abstract:
A system and method for mapping interpersonal relationships, the method including processing a multiplicity of images and contextual information relating thereto including creating and prioritizing a list of a plurality of candidate persons having at least a predetermined relationship with at least one person connected to at least one image, using multi-dimensional information including visually sensible information in the multiplicity of images and contextual information relating thereto and searching the list of a plurality of candidate persons based at least in part on the prioritizing to select at least one of the candidate persons as having at least a predetermined relationship with the at least one person.

Description:
PRIORITY REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit under 35 U.S.C. 120 of U.S. patent application Ser. No. 12/922,984, filed 15 Feb. 2011, which claims the benefit under 35 U.S.C. §365(c) of International Patent Application No. PCT/IL2009/000316, filed 19 Mar. 2009, which claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/070,377, filed 20 Mar. 2008, each of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to systems and methods for mapping interpersonal relationships. 
     BACKGROUND OF THE INVENTION 
     The following publications are believed to represent the current state of the art: 
     U.S. Pat. Nos. 5,164,992; 5,963,670; 6,292,575; 6,819,783; 6,944,319; 6,990,217; 7,274,822 and 7,295,687; and 
     U.S. Published Patent Application Nos.: 2006/0253491 and 2007/0237355. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to provide an improved system for mapping interpersonal relationships. There is thus provided in accordance with a preferred embodiment of the present invention a method for mapping interpersonal relationships including processing a multiplicity of images and contextual information relating thereto including creating and prioritizing a list of a plurality of candidate persons having at least a predetermined relationship with at least one person connected to at least one image, using multi-dimensional information including visually sensible information in the multiplicity of images and contextual information relating thereto and searching the list of a plurality of candidate persons based at least in part on the prioritizing to select at least one of the candidate persons as having at least a predetermined relationship with the at least one person. 
     There is additionally provided in accordance with a preferred embodiment of the present invention a system for mapping interpersonal relationships including processing functionality operative to process a multiplicity of images and contextual information relating thereto including creating and prioritizing a list of a plurality of candidate persons having at least a predetermined relationship with at least one person connected to at least one image, using multi-dimensional information including visually sensible information in the multiplicity of images and contextual information relating thereto and searching functionality operative to search the list of a plurality of candidate persons based at least in part on the prioritizing to select at least one of the candidate persons as having at least a predetermined relationship with the at least one person. 
     Preferably, the searching also employs the multi-dimensional information. 
     In accordance with a preferred embodiment of the present invention, the multi-dimensional information includes at least one of visual information appearing in an image, geographical information appearing in the image, visual background information appearing in the image, images of other persons appearing in the image and person identifiers appearing in the image and at least one of information relating to an image collection of which the image forms a part, a time stamp associated with the image, information not appearing in the image but associated therewith, geographical information not appearing in the image, visual background information appearing in another image and person identifiers not appearing in the image but otherwise associated therewith. 
     More preferably, the multi-dimensional information includes at least one of visual information appearing in an image, geographical information appearing in the image, visual background information appearing in the image, images of other persons appearing in the image and person identifiers appearing in the image and at least two of information relating to an image collection of which the image forms a part, a time stamp associated with the image, information not appearing in the image but associated therewith, geographical information not appearing in the image, visual background information appearing in another image and person identifiers not appearing in the image but otherwise associated therewith. 
     Even more preferably, the multi-dimensional information includes at least one of visual information appearing in an image, geographical information appearing in the image, visual background information appearing in the image, images of other persons appearing in the image and person identifiers appearing in the image and at least three of information relating to an image collection of which the image forms a part, a time stamp associated with the image, information not appearing in the image but associated therewith, geographical information not appearing in the image, visual background information appearing in another image and person identifiers not appearing in the image but otherwise associated therewith. 
     Most preferably, the multi-dimensional information includes all of the following: visual information appearing in an image, geographical information appearing in the image, visual background information appearing in the image, images of other persons appearing in the image; person identifiers appearing in the image, information relating to an image collection of which the image forms a part, a time stamp associated with the image, information not appearing in the image but associated therewith, geographical information not appearing in the image, visual background information appearing in another image and person identifiers not appearing in the image but otherwise associated therewith. 
     In accordance with a preferred embodiment of the present invention, the at least one image is a composite image, which includes images of multiple persons, at least one of whom is unknown. Alternatively, the at least one image is a composite image, which includes images of multiple persons, none of whom are known. 
     Preferably, the at least one person connected with the at least one image appears in the image. 
     In accordance with a preferred embodiment of the present invention, the method also includes tagging the at least one person connected with the at least one image with a person identifier. Additionally or alternatively, the processing includes iterative generation of relationship maps based on at least visually sensible information and also on additional, non-visually sensible information related to persons who either appear in the at least one image or are otherwise associated therewith. 
     Preferably, the non-visually sensible information is meta-data associated with image data. Additionally, the meta-data includes data derived from a social network. Alternatively or additionally, the meta-data includes data attached to the image data of the composite image. 
     In accordance with a preferred embodiment of the present invention, the iterative generation of relationship maps starts from a precursor relationship map, containing information on relationships of at least one known person in the at least one image. 
     Preferably, the relationship map is also based on inter-personal relationship data received from at least one of a social network and earlier instances of relationship mapping based on analysis of other images. Additionally or alternatively, the relationship map includes an indication of at least strength of the relationship between two persons. Alternatively or additionally, the relationship map includes a face representation which identifies each of the persons in the map. 
     In accordance with a preferred embodiment of the present invention, the relationship map includes an indication of whether each person in the map is a male or female. Additionally, the indication of whether each person in the map is a male or female is provided by at least one of a social network and operation of image attribute recognition. 
     Preferably, the prioritizing employs an indication of whether a person is a male or female. Additionally or alternatively, the prioritizing employs an indication of whether a person appears in the same album in a social network as another person appears. 
     In accordance with a preferred embodiment of the present invention, the processing includes seeking candidate persons having at least a predetermined relationship with a known person in at least one image. Additionally, the seeking candidate persons is carried out by starting with the generation of a list of candidate persons who have a temporal association with the known person based on visually-sensible information contained in the at least one image as well as non-visually sensible information. Additionally, the non-visually sensible information includes at least one of the time and geographical location where the composite image was taken and an identification of an album on a social network with which it is associated. Additionally or alternatively, the non-visually sensible information is obtained at least by interfacing with social network APIs to find persons who appeared in other pictures in the same album, or persons that appeared in other albums taken in the same geographical location at the same time. 
     Preferably, the list of candidate persons is extended and further prioritized by analyzing relationships of the persons appearing in a relationship map. In accordance with a preferred embodiment of the present invention, the prioritizing employs image attribute filtering. 
     In accordance with a preferred embodiment of the present invention, the processing includes facial representation generation performed on an unknown person in at least one image. Additionally, the method also includes comparing the facial representation with previously generated facial representations of the candidate persons in accordance with and in an order established by the prioritizing. Preferably, the comparing is terminated and a candidate person is selected when a combined priority/similarity threshold is reached for a given candidate person, the priority/similarity threshold taking into account the similarity of a facial representation of a candidate person to the facial representation of an unknown person, the priority of that candidate person established by the above-referenced prioritizing and the quality of the facial representation of the candidate person. 
     Preferably, user feedback confirming that the person whose image is believed to be a given person is or is not that person is employed in generation of a further iterative relationship map. Alternatively, user feedback confirming that the person whose image is believed to be a given person is or is not that person is employed in improving the face representation. 
     In accordance with a preferred embodiment of the present invention, the searching includes comparison of face representations of persons in the list of candidate persons with face representations of persons in the relationship map. 
     In accordance with a preferred embodiment of the present invention, the method also includes searching at least one of the relationship maps. Additionally, the searching of the at least one of the relationship maps employs search terms including at least one of uniquely identified persons, an additional image of a person, relationships between various persons, gender and face representations. Alternatively or additionally, the searching of the at least one of the relationship maps employs a user interface. Additionally or alternatively, the searching of the at least one of the relationship maps is carried out via at least one social network having access to the at least one of the relationship maps. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will be more fully understood and appreciated from the following detailed description, taken in conjunction with the drawings in which: 
         FIGS. 1A and 1B  are together a simplified generalized illustration of relationship mapping functionality, employing multi-dimensional context, including facial recognition, operative in accordance with a preferred embodiment of the present invention; and 
         FIG. 2  is a simplified functional block diagram of a system for relationship mapping employing multi-dimensional context including facial recognition in accordance with a preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference is now made to  FIG. 1A , which is a simplified generalized illustration of relationship mapping functionality employing multi-dimensional context, including facial recognition, operative in accordance with a preferred embodiment of the present invention. Facial recognition preferably includes facial representation generation and subsequent comparison of multiple facial representations. 
     The functionality may be understood and visualized by starting with a composite image, represented by a line drawing  100 , which includes images of multiple people, at least one of whom is known. In the present example, exemplified by line drawing  100 , one person, here labeled John, is known and a second person, here labeled Unknown, is not known. In this example, the person who took the picture represented by line drawing  100  is also known. 
     In accordance with a preferred embodiment of the invention in order to identify an unknown person, an iterative relationship map is generated based inter alia on visually sensible information contained in the composite image represented by line drawing  100  and also on additional, non-visually sensible information related to the above-mentioned persons who either appear in the composite image or are otherwise associated therewith. In a preferred embodiment, the non-visually sensible information may be meta-data attached to or associated with image data. The image data typically includes images in JPEG or PNG format. The meta-data may be data in XML or other suitable formats derived from a social network, such as FACEBOOK®, MYSPACE® AND FLICKR® as well as data conventionally attached to image data, such as XML, EXIF tag or other standard image contextual data. Typically, in the present example, John and Peter are uniquely known on a social network. The person who took the picture containing the composite image represented by line drawing  100  is identified as Greg, preferably by XML data attached to the image data of the composite image represented by line drawing  100 . 
     Generation of the relationship map preferably starts from a pre-existing iterative relationship map, here termed a precursor relationship map, represented by a diagram  102 , containing information on relationships of a known person or known persons in the composite image, in this case John. The precursor relationship map is also based on the inter-personal relationship data received from one or more social networks as well as inter-personal relationship data derived from earlier instances of operation of the relationship mapping functionality of the present invention based on analysis of other composite images. 
     Diagram  102  indicates that John, a male, is known to have a social relationship with Sharon, a female, who in turn has a social relationship with Mike, a male. John also has a social relationship with Peter, a male. The symbology employed in the relationship map indicates various parameters, including strength of the relationship between two persons. In the present example, a number inserted in a relationship indicating arrow indicates the strength of the relationship in the direction indicated by the arrow. The higher the number, the stronger the relationship in the illustrated example. 
     In the example of diagram  102 , the relationship between John and Mike is expected to be relatively strong, by virtue of the relationship between John and Sharon ( 85 ) and the relationship between Sharon and Mike ( 100 ), notwithstanding that it is an indirect relationship, through Sharon. This strength may be evidenced by multiple composite images in which Sharon appears with Mike and separately with John. The relationship between John and Peter is indicated, by the number  10 , to be relatively weak, notwithstanding that it is a direct relationship. For example John and Peter may both appear together only in one composite image and that image may include many other people. 
     The precursor relationship map also includes a face representation produced by conventional facial representation generation techniques, such as techniques described in either or both of U.S. Pat. No. 5,164,992, entitled “Face recognition system” and U.S. Pat. No. 6,292,575, entitled “Real-time facial recognition and verification system”. The face representation is typically in the form of a vector, which identifies each of the persons in the map. 
     The precursor relationship map also includes an indication of whether each person in the map is a male or female, indicated by the letters M and F. This indication may be provided by various sources, such as a social network or by operation of image attribute recognition, which may be entirely conventional, such as described in U.S. Pat. No. 6,990,217 entitled: “Gender classification with support vector machines”. Additional attributes may be generated by image attribute recognition and can be included within the precursor relationship map. These may include complexion, eye color and hair color. Conventional image attribute recognition is known to have accuracy of above 90% in determining gender. 
     The precursor relationship map and subsequent relationship maps preferably also include information from visual background analysis. 
     Generation of the relationship map employs information from the composite image represented by line drawing  100 , such as that John appears in the composite image together with an unknown individual. Image attribute analysis is preferably applied to the composite image represented by line drawing  100 , in order to determine whether the unknown individual is a male or a female. 
     In accordance with a preferred embodiment of the present invention, candidate persons having at least a predetermined relationship with the known person, John, in the composite image are sought. This is preferably done by starting with the generation of a list of candidate persons who have a temporal association with the known person based on visually-sensible information contained in the composite image as well as the non-visually sensible information typically available as meta-data. 
     Such non-visually sensible information may include the time and geographical location where a picture was taken and the album on a social network with which it is associated. For example, by interfacing with social network APIs, queries can be made to find persons who appeared in other pictures in the same album, or persons that appeared in other albums taken in the same geographical location at the same time. These persons would typically be on an initial list of candidate persons. 
     In accordance with a preferred embodiment of the present invention, the list of candidate persons is extended and further prioritized by analyzing relationships of the persons appearing in the precursor relationship map. In practice, the precursor relationship map may include millions of people. It is a particular feature of the present invention that prioritization of the persons appearing in the precursor relationship map is carried out. This prioritization preferably includes image attribute filtering, which eliminates persons who are of a gender other than the gender of the unknown person in the composite image. For example, referring to diagram  102 , the persons appearing are Mike and Sharon. Image attribute filtering is used to eliminate Sharon, since, image attribute recognition indicates that the unknown person in the composite image represented by line drawing  100  is a male. 
     The prioritization preferably relies heavily on the strengths of relationships between the known person and various other persons in the precursor relationship map and gives much higher priority to persons having the strongest relationship with the known person. Thus in the present example, Mike is prioritized over Peter. The prioritization is given expression in operation of the functionality of the present invention preferably by initially performing facial recognition on the images of persons having highest priority. Thus, when the pool of candidates includes millions of people, the prioritization which is a particular feature of the present invention, is of great importance. 
     Facial representation generation, which may be entirely conventional, is performed on the unknown person in the composite image represented by line drawing  100 . The resulting facial representation is compared with previously generated facial representations of the candidate persons in accordance with and in the order established by the above-described prioritization. The result of the comparison is a metric depicting the similarity between the two different facial representations. The comparison is cut off and a candidate is selected when a combined priority/similarity threshold is reached for a given candidate person. 
     The priority/similarity threshold takes into account the similarity of a facial representation of a candidate person to the facial representation of the unknown person, the priority of that candidate person established by the above-referenced prioritization and a metric which indicates the quality of the facial representation of the candidate person. This metric is a function of various parameters, such as the number of images of that person that have been analyzed by the system and previous user feedback. A preferred quality metric, Qi, is given by the following expression: 
     
       
         
           
             Qi 
             = 
             
               
                 [ 
                 
                   
                     [ 
                     
                       1 
                       - 
                       
                         
                           ( 
                           
                             1 
                             n 
                           
                           ) 
                         
                         2 
                       
                     
                     ] 
                   
                   × 
                   q 
                 
                 ] 
               
               × 
               
                 [ 
                 
                   
                     tp 
                     fp 
                   
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                       ( 
                       
                         1 
                         fn 
                       
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     where n is the count of images including the face representation, fp is the percent of false positives indicated so far by user feedback, tp is the percent of true positives indicated so far by user feedback, fn is the percent of false negatives indicated so far by user feedback and q is a weighting of variance of the vectors representing the images that compose the face representation. 
     The match between the unknown person and the selected candidate person is then employed to provide an initial revised relationship map, indicated by a diagram  104 . In the illustrated example, the unknown person is tentatively identified as Mike and the relationship between Mike and John is initially indicated as being a relatively weak relationship. It is noted that Greg also appears in diagram  104  as having a weak one-directional relationship with John, based on Greg having taken the photograph containing the composite image represented by line drawing  100 . 
     If any positive user feedback is received via a social network confirming that the person whose image is believed to be Mike is indeed Mike, this feedback is used to strengthen the relationship between Mike and John as expressed in a subsequent revised relationship map, not shown, and to strengthen the metric which indicates the quality of the facial representation of Mike. Conversely, receipt of negative feedback indicating that the person whose image is believed to be Mike is not Mike weakens the relationship between Mike and John as expressed in a subsequent revised relationship map, not shown, and weakens the metric which indicates the quality of the facial representation of Mike. Additionally it serves as a negative example for future facial representation comparison. 
     Reference is now made to  FIG. 1B , which is another simplified generalized illustration of relationship mapping functionality employing multi-dimensional context, including facial recognition, operative in accordance with a preferred embodiment of the present invention. 
     The functionality may be understood and visualized by starting with a composite image, represented by a line drawing  200 , which includes images of multiple people. In the present example, exemplified by line drawing  200 , three persons here labeled Unknown 1, Unknown 2 and Unknown 3, appear. All are not known. In this example, the person who uploaded the picture to the social network site represented by line drawing  200  is known to be the abovementioned John. Identification of the unknown persons preferably employs relationship mapping. 
     Generation of a relationship map preferably begins from a pre-existing iterative relationship map, for example a precursor relationship map, represented by a diagram  202 , which is identical to diagram  104 . This precursor relationship map contains information on relationships of a known person or known persons in the previously analyzed composite image, in this case John, Peter, Greg and Sharon. This information is based on the inter-personal relationship data received from one or more social networks as well as inter-personal relationship data derived from the earlier instance of operation of the relationship mapping functionality of the present invention based on analysis of other composite images. 
     Diagram  202  indicates that John, a male, is known to have a strong social relationship with Sharon, a female, who in turn has a strong social relationship with Mike, a male. John is also indicated to have weak social relationships with Peter, Greg and Mike, who are males. 
     In accordance with a preferred embodiment of the present invention, candidate persons having at least a predetermined relationship with the known person, John, who uploaded the picture represented by line drawing  200 , are sought. This is preferably done by starting with the persons appearing in the precursor relationship map  202 . As noted above, it is a particular feature of the present invention that prioritization of the persons appearing in the precursor relationship map is carried out. 
     The prioritization preferably relies heavily on the strength of the relationship between the known person, John, and other persons in the relationship map  202  and gives much higher priority to persons having the strongest relationship with the known person, John. Thus in the present example, John is prioritized above all, as having the strongest relationship to himself. After John, Mike has the next highest priority, since Sharon is eliminated by her gender. 
     After Mike, Peter has a higher priority than Greg, notwithstanding that both of their relationship arrows are given the same numerical score, since the relationship between John and Greg is only known to be unidirectional. 
     Prioritization preferably is also based on a certainty metric. In this case, the certainty that John is one of the unknown persons in the composite image  200  initially is not particularly high. In view of this, a prioritization cut-off is implemented, such that Peter and Greg, who have relatively weak relationships with John, are not considered to be candidates. As noted above, prioritization is given expression in operation of the functionality of the present invention preferably by initially performing facial recognition on the persons having highest priority, starting with John. 
     Facial representation generation is performed on the unknown persons in the composite image represented by line drawing  200 . The resulting facial representation is compared with previously generated facial representations of the candidate persons in accordance with and in the order established by the above-described prioritization. 
     For example, facial representation generation is performed on the three unknown images within composite image represented by a line drawing  200 . Thereafter comparison of the facial representations of the three unknown persons is carried out in accordance with the prioritized list generated above. The priority/similarity threshold for each is evaluated, and thus Unknown 1 is recognized as John, Unknown 2 and Unknown 3 are yet to be recognized. 
     In accordance with a preferred embodiment of the present invention, following recognition of Unknown 1 as John, in order to recognize the remaining unknown persons in the composite image, an additional prioritization iteration is carried out. In this additional prioritization iteration, the identification of Unknown 1 as John increases the certainty metric for persons known to have a relationship with John and thus Peter is considered to be a candidate. Greg is still typically not considered to be a candidate since his relationship with John is unidirectional. Mike is typically not considered again inasmuch as a previous comparison of Mike with the generated unknown face representation generated a low similarity metric. 
     A new priority list includes Peter, based on his relationship with John, who is now known to be previously Unknown 1 in the composite image represented by line drawing  200 . 
     Facial representations of the remaining unknown persons in the composite image represented by line drawing  200  are compared with previously generated facial representations of the candidate persons in accordance with and in the order established by the revised prioritization. 
     For example, Unknown 2 is recognized as Peter and Unknown 3 is yet to be recognized. 
     In accordance with a preferred embodiment of the present invention, following recognition of Unknown 2 as Peter, in order to recognize the last unknown person in the composite image, a further prioritization iteration is carried out. In this further prioritization iteration, the identification of Unknown 2 as Peter indicates that there are two starting points for generation, of candidate lists, John and Peter, both of whom are known to be in the composite image. Two candidate list subsets may thus be provided and used to generate a single prioritized list by using weighted graph combination techniques, as known in the art. 
     At this stage a further relationship map is generated, as indicated by reference numeral  204 . In this relationship map, the indicated relationship between John and Peter is strengthened. Relationships between Unknown 3, John and Peter are also indicated based on the composite image represented by line drawing  200 . 
     Unknown 3 may then be recognized in the future by comparing the facial representation of Unknown 3 with facial representations of persons who are subsequently indicated to have relationships with John or with the other persons appear in the relationship map  204 . 
     Reference is now made to  FIG. 2 , which is simplified functional block diagram of a system for relationship mapping employing multi-dimensional context including facial recognition in accordance with a preferred embodiment of the present invention. As seen in  FIG. 2 , the present invention utilizes one or more publicly available social network application program interfaces (APIs)  300 , such as the APIs provided by FACEBOOK®, MYSPACE® AND FLICKR®. Examples of such APIs include the Facebook API, Facebook Connect, Picasa Web Albums Data API and the Flickr Services API. 
     The system communicates interactively with the APIs  300  via widgets  302  which may be embedded within applications such as FACEBOOK®, MYSPACE® AND FLICKR®, or standalone applications such as local album indexers  304 . The system automatically receives updates from APIs  300  via crawlers  306 , such as image crawlers, video crawlers and relationship crawlers, such as those used by spammers. Elements  302 ,  304  and  306  preferably include user interface functionality. The user interface functionality may be used to provide positive or negative feedback regarding whether a recognized person is indeed the named person. This feedback is communicated to relationship mapping coordination functionality  310  and used to strengthen or weaken the face representation. Additional user interface functionality includes search functionality operative to search the generated relationship map. Search terms include, for example, uniquely identified persons, an additional image of a person, relationships between various persons, other system generated attributes such as gender or facial representation resemblance and any suitable combination of the above. Search functionality can be provided directly via a user interface or indirectly by exposing the relationship mapper  322  information to social networks. 
     Standalone applications may include running on an end-user machine and performing some or all of the image attribute analysis, facial representation generation and facial representation comparison. In a preferred embodiment of the present invention, a local album indexer  304  performs image attribute analysis, facial representation generation and facial representation comparison operations, and communicates with the relationship mapping coordination functionality  310  to generate a unified facial representation from multiple images of a single person. 
     Relationship mapping coordination functionality is preferably responsive both to API sourced information from APIs  300  and to user inputs received via communicators such as widgets  302 , local album indexers  304  and crawlers  306  and coordinates operation of the various elements of the system which are described hereinbelow. 
     The heart of the system of the present invention preferably includes an expectation engine  320  which interfaces with a relationship mapper  322 , which in turn interfaces with a relationship map database  324 . These elements utilize information obtained by functionality  310  from face recognition functionality  326  and attribute analysis functionality  328  via an image analysis engine  330 . Preferably a video analysis engine  332  cooperates with interframe analysis functionality  334  and intraframe analysis functionality  336 , which provide information based on temporal sequences of frames in video content. 
     Relationship mapper  322  functionality preferably include providing access to a weighted graph of strengths of the relationships between various uniquely identified persons. Each node in the graph represents a single person and includes a list of unique identifiers that can be one or more of an email address, an internet identifier like OpenID or a list of IDs of specific social networks. In addition, the node preferably contains a facial representation generated from one or more images of the person, his or her gender and other information relating to the person. The relationship map is stored at least partially in memory and is preferably available persistently via relationship database  324 . 
     The expectation engine  320  preferably generates prioritized lists of candidate persons, listing persons expected to appear in a composite image, its associated data and social network data. Initially, the expectation engine queries the social networks via APIs  300  for a list of candidate persons having a temporal association with the known person based on visually-sensible information contained in the composite image as well as the non-visually sensible information typically available as meta-data. 
     Subsequently, the expectation engine functionality performs prioritization of the candidate persons expected to appear in the composite image by interfacing with relationship mapper  322  and by utilizing image attribute filtering provided by the image analysis engine  330 . The prioritization preferably relies heavily on the strength of relationship between the known person and other persons in the relationship map and gives much higher priority to persons having the strongest relationship with the known person. In a preferred embodiment, the expectation engine combines the weighted graphs associated with known persons in the composite image, as provided by relationship mapper  322  by utilizing weighted graph combination algorithms. 
     It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the invention includes both combinations and sub-combinations of various features described hereinabove as well as modifications and variations thereof which would occur to a person skilled in the art upon reading the foregoing description and which are not in the prior art.