| Wavelet Toolbox™ | |
| Provide feedback about this page |
Multisignal 1-D wavelet compression scores
Syntax
[THR,L2SCR,NOSCR,IDXSORT] = mswcmpscr(DEC) [THR,L2SCR,NOSCR,IDXSORT] = mswcmpscr(DEC,S_OR_H,KEEPAPP,IDXSIG)
Description
[THR,L2SCR,NOSCR,IDXSORT] = mswcmpscr(DEC) computes four matrices: thresholds THR, compression scores L2SCR and NOSCR, and indices IDXSORT. The decomposition DEC corresponds to a matrix of wavelet coefficients CFS obtained by concatenation of detail and (optionally) approximation coefficients, where
CFS = [cd{DEC.level}, ... , cd{1}] or CFS = [ca, cd{DEC.level}, ... , cd{1}]
The concatenation is made rowwise if DEC.dirDec is equal to 'r' or columnwise if DEC.dirDec is equal to 'c' .
If NbSIG is the number of original signals and NbCFS the number of coefficients for each signal (all or only the detail coefficients), then CFS is an NbSIG-by-NbCFS matrix. Therefore,
THR, L2SCR, NOSCR are NbSIG-by-(NbCFS+1) matrices
IDXSORT is an NbSIG-by-NbCFS matrix
THR(:,2:end) is equal to CFS sorted by row in ascending order with respect to the absolute value.
IDXSORT contains the order of coefficients and THR(:,1)=0.
L2SCR(i,j) is the percentage of preserved energy (L2-norm), corresponding to a threshold equal to CFS(i,j-1) (2 
j NbCFS), and L2SCR(:,1)=100.
N0SCR(i,j) is the percentage of zeros corresponding to a threshold equal to CFS(i,j-1) (2 j NbCFS), and N0SCR(:,1)=0.
Three more optional inputs may be used:
[...] = mswcmpscr(...,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 that contains the indices of the initial signals, or the string '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 performances for soft an hard thresholding. [THR_S,L2SCR_S,N0SCR_S] = mswcmpscr(dec,'s'); [THR_H,L2SCR_H,N0SCR_H] = mswcmpscr(dec,'h');
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
mdwtdec, mdwtrec, ddencmp, wdencmp
| Provide feedback about this page |
| mswcmp | mswcmptp | |
| © 1984-2008- The MathWorks, Inc. - Site Help - Patents - Trademarks - Privacy Policy - Preventing Piracy - RSS |