ABSTRACT

FIGURE 6.1 (a) Transform-based coder. (b) Subband decomposition used in the FBI fingerprint compression standard.

Both orthogonal [73] and bi-orthogonal [1, 70] wavelets have been used for image compression. The recent FBI fingerprint compression standard [70] uses symmetric dyadic wavelets and significantly outperforms the JPEG (Joint Picture Expert Group) standard [38] at compression ratios above 10:1. Fig. 6.1(b) shows the subband decomposition used in the FBI fingerprint compression standard. Interestingly, the wavelet tree used in the FBI specification is a predominantly 4-channel decomposition achieved by cascading 2-channel filter banks.