606974.fig.001a
(a)
606974.fig.001b
(b)
606974.fig.001c
(c)
606974.fig.001d
(d)
Figure 1: Example of sparse representations in the wavelet domain: (a) piecewise smooth signal; (b) wavelet transform of piecewise smooth signal, only few coefficients are significant and they are compressible or near sparse; (c) the significant coefficients are well organized in tree structure across the scales; (d) binary tree for piecewise smooth signal, the significant wavelet coefficients arise from the discontinuities in the signal (the black circles denote the large wavelet coefficients).