Fig. 5.
Illustration of the proposed method. An input image is decomposed into its approximation and detail subbands through wavelet decomposition. As the image is reconstructed back, bilateral filtering is applied to the approximation subbands, and wavelet thresholding is applied to the detail subbands. The analysis and synthesis filters (La, Ha, Ls, and Hs) form a perfect reconstruction filter bank. The illustration shows one approximation subband and one detail subband at each decomposition level; this would be the case when the data is one dimensional. For a two-dimensional data, there are in fact one approximation and three (horizontal, vertical, and diagonal) detail subbands at each decomposition level. Also, in the illustration, there are two levels of decomposition; the approximation subbands could be decomposed further in an application.