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Single-level reconstruction of 1-D wavelet decomposition


[NC,NL,cA] = upwlev(C,L,'wname')


upwlev is a one-dimensional wavelet analysis function.

[NC,NL,cA] = upwlev(C,L,'wname') performs the single-level reconstruction of the wavelet decomposition structure [C,L] giving the new one [NC,NL], and extracts the last approximation coefficients vector cA.

[C,L] is a decomposition at level n = length(L)-2, so [NC,NL] is the same decomposition at level n-1 and cA is the approximation coefficients vector at level n.

'wname' is a string containing the wavelet name, C is the original wavelet decomposition vector, and L the corresponding bookkeeping vector (for detailed storage information, see wavedec ).

Instead of giving the wavelet name, you can give the filters.

For [NC,NL,cA] = upwlev(C,L,Lo_R,Hi_R), Lo_R is the reconstruction low-pass filter and Hi_R is the reconstruction high-pass filter.


% The current extension mode is zero-padding (see dwtmode).

% Load original one-dimensional signal.
load sumsin; s = sumsin; 

% Perform decomposition at level 3 of s using db1. 
[c,l] = wavedec(s,3,'db1'); 
subplot(311); plot(s); 
title('Original signal s.'); 
subplot(312); plot(c); 
title('Wavelet decomposition structure, level 3') 
xlabel(['Coefs for approx. at level 3 ' ... 
        'and for det. at levels 3, 2 and 1'])

% One step reconstruction of the wavelet decomposition 
% structure at level 3 [c,l], so the new structure [nc,nl] 
% is the wavelet decomposition structure at level 2. 
[nc,nl] = upwlev(c,l,'db1'); 
subplot(313); plot(nc); 
title('Wavelet decomposition structure, level 2') 
xlabel(['Coefs for approx. at level 2 ' ... 
        'and for det. at levels 2 and 1'])

% Editing some graphical properties,
% the following figure is generated.

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