Syntax

Description

[THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH)or[THR_VAL,L2_Perf,N0_Perf] = mswcmptp(DEC,METH,PARAM)computes the vectorsTHR_VAL,L2_PerfandN0_Perfobtained after a compression using theMETHmethod and, if required, thePARAMparameter (seemswcmpfor more information onMETHandPARAM).

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 levelj

• 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 (seemswthreshfor more details).

• KEEPAPP(真或假)indicates whether to keep approximation coefficients (true) or not (false)

• IDXSIGis a vector which contains the indices of the initial signals, or the character vector'all'.

The defaults are, respectively,'h', false and'all'.

Examples

% 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);

References

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.)

See Also

ddencmp|mdwtdec|mdwtrec|wdencmp