Region-based representations of image and video: Segmentation tools for multimedia services

This paper discusses region-based representations of image and video that a re useful for multimedia services such as those supported by the MPEG-4 and MPEG-7 standards. Classical tools related to the generation of the region- based representations are discussed. After a description of the main proces sing steps and the corresponding choices in terms of feature spaces, decisi on spaces, and decision algorithms, the state of the art in segmentation is reviewed. Mainly tools useful in the context of the MPEG-4 and MPEG-7 stan dard are discussed. The review is structured around the strategies used by the algorithms (transition based or homogeneity based) and the decision spa ces (spatial, spatio-temporal, and temporal). The second part of this paper proposes a partition tree representation of i mages and introduces a processing strategy that involves a similarity estim ation step followed by a partition creation step. This strategy tries to fi nd a compromise between what can be done in a systematic and universal way and what has to be application dependent, It is shown in particular how a s ingle partition tree created with an extremely simple similarity feature ca n support a large number of segmentation applications: spatial segmentation , motion estimation, region-based coding, semantic object extraction, and r egion-based retrieval.