8. A computer program product embodied in a non-transitory computer readable storage medium for efficiently identifying images, videos, audio files or documents relevant to a user, the computer program product comprising the programming instructions for: determining a set of attribute ranking functions, each of which predicts or assigns a relative strength of an attribute in an image, video, audio file or document from a pool of ranked database images, videos, audio files or documents; presenting a set of reference images, videos, audio files or documents from said pool of database images, videos, audio files or documents; receiving a selection of one or more images, videos, audio files or documents from said set of reference images, videos, audio files or documents along with relative attribute feedback pertaining to one or more attributes of said selected one or more images, videos, audio files or documents, wherein said relative attribute feedback comprises feedback regarding a desired degree of a characteristic of an attribute; and revising a system's model of what images, videos, audio files or documents are relevant to said user by updating one or more relevance ranking functions of a set of relevance ranking functions using said relative attribute feedback and said set of attribute ranking functions, wherein said set of relevance ranking functions are used to rank said database images, videos, audio files or documents based on how relevant said database images, videos, audio files or documents are to a user's search.
8. A computer program product embodied in a non-transitory computer readable storage medium for efficiently identifying images, videos, audio files or documents relevant to a user, the computer program product comprising the programming instructions for: determining a set of attribute ranking functions, each of which predicts or assigns a relative strength of an attribute in an image, video, audio file or document from a pool of ranked database images, videos, audio files or documents; presenting a set of reference images, videos, audio files or documents from said pool of database images, videos, audio files or documents; receiving a selection of one or more images, videos, audio files or documents from said set of reference images, videos, audio files or documents along with relative attribute feedback pertaining to one or more attributes of said selected one or more images, videos, audio files or documents, wherein said relative attribute feedback comprises feedback regarding a desired degree of a characteristic of an attribute; and revising a system's model of what images, videos, audio files or documents are relevant to said user by updating one or more relevance ranking functions of a set of relevance ranking functions using said relative attribute feedback and said set of attribute ranking functions, wherein said set of relevance ranking functions are used to rank said database images, videos, audio files or documents based on how relevant said database images, videos, audio files or documents are to a user's search. 9. The computer program product as recited in claim 8 further comprising the programming instructions for: training said set of relevance ranking functions using said relative attribute feedback.