KMi Seminars
Local Similarity Search for Content-based Image Retrieval
This event took place on Wednesday 29 November 2006 at 11:30

 
Peter Howarth Imperial College London, and KMi, The Open University

The goal of content-based image retrieval (CBIR) is to provide the user with a way to browse or retrieve images from large collections based on visual similarity. At the heart of any CBIR system are visual features that have been extracted from images and (dis)similarity functions that are used to quantify the similarity between these features. The combination of these two components will drive the overall performance of a system.

Two frequently studied research areas in CBIR are maximising retrieval performance using similarity measures and improving the efficiency and speed of search by applying indexing methods. Often these are mutually exclusive. The best performing similarity measures are usually computationally expensive and the optimal indexing approaches can place many restrictions on what features and similarity functions can be used.

In this talk we investigate how to localise the measurement of similarity. That is, emphasise points that are close to the query in some subspace of the full feature space. We show that this has dual benefits for CBIR, both improving retrieval performance and speeding up the search of high-dimensional features.

 
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Multimedia and Information Systems is...


Multimedia and Information Systems
Our research is centred around the theme of Multimedia Information Retrieval, ie, Video Search Engines, Image Databases, Spoken Document Retrieval, Music Retrieval, Query Languages and Query Mediation.

We focus on content-based information retrieval over a wide range of data spanning form unstructured text and unlabelled images over spoken documents and music to videos. This encompasses the modelling of human perception of relevance and similarity, the learning from user actions and the up-to-date presentation of information. Currently we are building a research version of an integrated multimedia information retrieval system MIR to be used as a research prototype. We aim for a system that understands the user's information need and successfully links it to the appropriate information sources, be it a report or a TV news clip. This work is guided by the vision that an automated knowledge extraction system ultimately empowers people making efficient use of information sources without the burden of filing data into specialised databases.

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