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.