Extraction of query term-related visual phrases for news video retrieval using mutual information

This paper presents an approach to query term-related visual phrases extraction using mutual information for object-based news video retrieval. As visual words are useful for object representation, unstable visual words generally appear in the frame sequence of a shot. Using the appearance frequency of the visual words in a sliding window over the query term-related stories, the appearance pattern of a visual word is adopted to characterize the visual word. Based on the appearance pattern of a visual word, the mutual information between two visual words can be estimated over all of the extracted stories. The mutual information is then used to construct a visual word relation graph. Visual phrases are then extracted by discovering the complete sub-graphs from the visual word relation graph for news video retrieval. Experiments were conducted on the MATBN news video database and the experimental results show that a good precision rate for video news retrieval can be achieved.