A modified shape descriptor in wavelets compressed domain

In order to implement shape-based image retrieval in the wavelet domain effectively and efficiently, a new method is introduced to improve the moment-based shape descriptor. Firstly, several morphological operations are used to incorporate isolated significant points of a wavelet coefficient domain into a meaningful object region, which leads to a more accurate shape description. Then, by using the invariant properties of certain moments, a compact moment representation method is also proposed to integrate shape information spread at various directional wavelet subbands. Experimental results show that the proposed algorithm outperforms the existing shape-based image retrieval method in the wavelet domain.