# upcoef2

Direct reconstruction from 2-D wavelet coefficients

## Syntax

```Y = upcoef2(O,X,wname,N,S) Y = upcoef2(O,X,Lo_R,Hi_R,N,S) Y = upcoef2(O,X,wname,N) Y = upcoef2(O,X,Lo_R,Hi_R,N) Y = upcoef2(O,X,wname) Y = upcoef2(O,X,wname,1) Y = upcoef2(O,X,Lo_R,Hi_R) Y = upcoef2(O,X,Lo_R,Hi_R,1) ```

## Description

`upcoef2` is a two-dimensional wavelet analysis function.

`Y = upcoef2(O,X,wname,N,S)` computes the `N`-step reconstructed coefficients of matrix `X` and takes the central part of size `S`. `wname` is a character vector or string scalar specifying the wavelet. See `wfilters` for more information.

If `O = 'a'`, approximation coefficients are reconstructed; otherwise if `O = 'h'` (`'v'` or `'d'`, respectively), horizontal (vertical or diagonal, respectively) detail coefficients are reconstructed. `N` must be a strictly positive integer.

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

For `Y = upcoef2(O,X,Lo_R,Hi_R,N,S)` is the reconstruction low-pass filter and `Hi_R` is the reconstruction high-pass filter.

`Y = upcoef2(O,X,wname,N)` or ```Y = upcoef2(O,X,Lo_R,Hi_R,N)``` returns the computed result without any truncation.

`Y = upcoef2(O,X,wname)` is equivalent to `Y = upcoef2(O,X,wname,1)`.

`Y = upcoef2(O,X,Lo_R,Hi_R)` is equivalent to
`Y = upcoef2(O,X,Lo_R,Hi_R,1)`.

## 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 db4. [c,s] = wavedec2(X,2,'db4'); % Reconstruct approximation and details % at level 1, from coefficients. % This can be done using wrcoef2, or % equivalently using: % % Step 1: Extract coefficients from the % decomposition structure [c,s]. % % Step 2: Reconstruct using upcoef2. siz = s(size(s,1),:); ca1 = appcoef2(c,s,'db4',1); a1 = upcoef2('a',ca1,'db4',1,siz); chd1 = detcoef2('h',c,s,1); hd1 = upcoef2('h',chd1,'db4',1,siz); cvd1 = detcoef2('v',c,s,1); vd1 = upcoef2('v',cvd1,'db4',1,siz); cdd1 = detcoef2('d',c,s,1); dd1 = upcoef2('d',cdd1,'db4',1,siz); ```

## Algorithms

See `upcoef`. 