Multisignal 1-D compression thresholds and performances
[THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH)
[THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH,PARAM)
[THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH) or [THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH,PARAM) computes the vectors THR_VAL, L2_Perf and N0_Perf obtained after a compression using the METH method and, if required, the PARAM parameter (see mswcmp for more information on METH and PARAM).
For the ith signal:
THR_VAL(i) is the threshold applied to the wavelet coefficients. For a level dependent method, THR_VAL(i,j) is the threshold applied to the detail coefficients at level j.
L2_Perf(i) is the percentage of energy (L2_norm) preserved after compression.
N0_Perf(i) is the percentage of zeros obtained after compression.
You can use three more optional inputs:
[...] = mswcmptp(...,S_OR_H,KEEPAPP,IDXSIG)
S_OR_H ('s' or 'h') stands for soft or hard thresholding (see mswthresh for more details).
KEEPAPP (true or false) indicates whether to keep approximation coefficients (true) or not (false)
IDXSIG is a vector which contains the indices of the initial signals, or the string 'all'.
The defaults are, respectively, 'h', false and 'all'.
% Load original 1D-multisignal. load thinker % Perform a decomposition at level 2 using wavelet db2. dec = mdwtdec('r',X,2,'db2'); % Compute compression thresholds and exact performances % obtained after a compression using the method 'N0_perf' and % requiring a percentage of zeros near 95% for the wavelet % coefficients. [THR_VAL,L2_Perf,N0_Perf] = mswcmptp(dec,'N0_perf',95);
Daubechies, I. (1992), Ten lectures on wavelets, CBMS-NSF conference series in applied mathematics. SIAM Ed.
Mallat, S. (1989), "A theory for multiresolution signal decomposition: the wavelet representation," IEEE Pattern Anal. and Machine Intell., vol. 11, no. 7, pp. 674–693.
Meyer, Y. (1990), Ondelettes et opérateurs, Tome 1, Hermann Ed. (English translation: Wavelets and operators, Cambridge Univ. Press. 1993.)