An Enhanced Informed Watermarking Scheme Using the Posterior Hidden Markov Model
Figure 1
Illustration of wavelet pyramid decomposition, the VWD-HMM, and a vector quad-tree of wavelet coefficients (3 levels). The square block with thick solid lines denotes the LL1 subband at the finest pyramid level, which is further decomposed to form the subbands of LH2, HL2, HH2, and LL2 at the second level. And so do the four subbands at the third level.
