IEEE TRANSACTIONS ON MULTIMEDIA 1 Content-based Copy Retrieval using Distortion-based Proba.pdf

IEEE TRANSACTIONS ON MULTIMEDIA 1 Content-based Copy Retrieval using Distortion-based Probabilistic Similarity Search Alexis Joly(1), Olivier Buisson(2) and Carl Fre?licot(3) Abstract— Content-based copy retrieval (CBCR) aims at re- trieving in a database all the modified versions or the previous versions of a given candidate object. In this paper, we present a copy retrieval scheme based on local features that can deal with very large databases both in terms of quality and speed. We first propose a new approximate similarity search technique in which the probabilistic selection of the feature space regions is not based on the distribution in the database but on the distribution of the features distortion. Since our CBCR framework is based on local features, the approximation can be strong and reduce drastically the amount of data to explore. Furthermore, we show how the discrimination of the global retrieval can be enhanced during its post-processing step, by considering only the geometrically consistent matches. This framework is applied to robust video copy retrieval and extensive experiments are presented to study the interactions between the approximate search and the retrieval efficiency. Largest used database contains more than one billion local features corresponding to 30, 000 hours of video. I. INTRODUCTION THE principle of CBCR is close to usual Content-BasedImage or Video Retrieval schemes (CBIR) when using the query by example paradigm [6], [7], [8], [9]. One differ- ence is that the queries are not examples given by a user but a stream of candidate documents automatically extracted from a particular medium (for example a television stream or a web downloader). The other and main difference is that the objects in demand are not the same. While general CBIR methods try to bridge the semantic gap, CBCR aims at recognizing a given document. Content-based retrieval methods dedicated to copy detection have emerged in recent years for monitoring and copyright