16. A system for multimedia information retrieval comprising: a search engine for querying an associated multimedia collection with a first component of a multimedia query and for querying at least a part of the queried multimedia collection with a second component of the multimedia query; a first comparison component for generating a first comparison measure between the first query component and a respective object in the collection for a first media type; a second comparison component for generating a second comparison measure between the second query component and a respective object in the collection for the second media type; a multimedia scoring component for generating aggregated scores for each of a set of objects in the collection based on the first comparison measure and the second comparison measure for the respective object, the multimedia scoring component applying an aggregating function which aggregates the first and second comparison measure in which a first confidence weighting is applied to the first comparison measure which is independent of the second comparison measure and a second confidence weighting is applied to the second comparison measure which is dependent on the first comparison measure, wherein the aqqreqatinq function is of general format: 
 s cw ( q,o )=α a N ( s a ( q,o )ƒ( s a ( q,o ), r a ( o,q ),θ a ))+α b N ( s b ( q,o ) g ( s a ( q,o ), r a ( o,q ), s b ( q,o ), r b ( o,q ),θ b ) wherein 0<α a <1, 0<α b <1 and α b =1−α a ; S cw is the aggregated score; a represents the first media type; b represents the second media type; s a (q,o) and s b (q,o) are similarity scores between the query q and the object o for the first and second media types respectively; r a (o,q) and r b (o,q) are rankinqs of the object o given by the respective similarity scores s a (q,o) and s b (q,o), with respect to other objects in the collection; ƒ is a function of at least one of r a (o,q) and s a (q,o) and optionally also of θ a ; g is a function of at least one of r a (o,q) and s a (q,o) and at least one of s b (q,o) and r b (o,q) and optionally also of θ b ; θ a is a set of one or more parameters; θ b is a set of one or more parameters; and N represents an optional normalizing operator; and a processor for implementing the search engine, first and second comparison components, and multimedia scoring component.
18. The system of claim 16 , wherein the system is configured for outputting retrieved objects from the collection based on their aggregated scores.