Fast wavelet histogram techniques for image indexing

Content-based image indexing is emerging as an important research area with application to digital libraries and multimedia databases. A majority of i ndexing techniques are based on pixel domain features such as histogram, co lor, texture, and shape. However, with recent advances in image compression , compressed domain indexing techniques are gaining popularity due to their low complexity. Recently, a wavelet histogram technique which exploits the directional properties of wavelet transform has been proposed in the liter ature. Although, this technique provides a good retrieval performance for t exture images, its complexity is very high. In this paper, we propose three techniques to reduce the complexity of the wavelet histogram method. These techniques together provide a superior performance at a substantially redu ced complexity and, hence, can be considered as a potential candidate for d eveloping a joint wavelet-based image storage and retrieval system. (C) 199 9 Academic Press.