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,`

performs
the single-level reconstruction of the wavelet decomposition structure * 'wname'*)

`[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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