# upwlev2

Single-level reconstruction of 2-D wavelet decomposition

## Syntax

```[NC,NS,cA] = upwlev2(C,S,wname) [NC,NS,cA] = upwlev2(C,S,Lo_R,Hi_R) ```

## Description

`upwlev2` is a two-dimensional wavelet analysis function.

`[NC,NS,cA] = upwlev2(C,S,wname)` performs the single-level reconstruction of wavelet decomposition structure `[C,S]` giving the new one `[NC,NS]`, and extracts the last approximation coefficients matrix `cA`.

`[C,S]` is a decomposition at level ```n = size(S,1)-2```, so `[NC,NS]` is the same decomposition at level `n`-1 and `cA` is the approximation matrix at level `n`.

`wname` is a character vector or string scalar specifying the wavelet, `C` is the original wavelet decomposition vector, and `S` the corresponding bookkeeping matrix (for detailed storage information, see `wavedec2`).

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

For `[NC,NS,cA] = upwlev2(C,S,Lo_R,Hi_R)`, `Lo_R` is the reconstruction low-pass filter and `Hi_R` is the reconstruction high-pass filter.

## Examples

```% The current extension mode is zero-padding (see `dwtmode`). % Load original image. load woman; % X contains the loaded image. % Perform decomposition at level 2 % of X using db1. [c,s] = wavedec2(X,2,'db1'); sc = size(c) sc = 1 65536 val_s = s val_s = 64 64 64 64 128 128 256 256 % One step reconstruction of wavelet % decomposition structure [c,s]. [nc,ns] = upwlev2(c,s,'db1'); snc = size(nc) snc = 1 65536 val_ns = ns val_ns = 128 128 128 128 256 256 ```

## Version History

Introduced before R2006a