Hierarchical navigation and visual search for video keyframe retrieval

Abstract

This work presents a browser that supports two strategies for video browsing: the navigation through visual hierarchies and the retrieval of similar images and objects. The input videos are rstly pro- cessed by a keyframe extractor to reduce the temporal redundancy and decrease the number of elements to consider. These generated keyframes are hierarchically clustered with the Hierachical Cellular Tree (HCT) algorithm, an indexing technique that also allows the creation of data structures suitable for browsing. Di erent clustering criteria are avail- able, in the current implementation, based on four MPEG-7 visual de- scriptors computed at the global scale. The navigation can directly drive the user to nd the video timestamps that best match the query or to a keyframe which is globally or locally similar in visual terms to the query. If this is the case, a visual search engine is also available to nd other similar keyframes or regions, also based on MPEG-7 visual descriptors.