# wrcoef2

Reconstruct single branch from 2-D wavelet coefficients

## Syntax

```X = wrcoef2('type',C,S,'wname',N)X = wrcoef2('type',C,S,Lo_R,Hi_R,N)X = wrcoef2('type',C,S,'wname')X = wrcoef2('type',C,S,Lo_R,Hi_R)```

## Description

`wrcoef2` is a two-dimensional wavelet analysis function. `wrcoef2` reconstructs the coefficients of an image.

`X = wrcoef2('type',C,S,'wname',N)` computes the matrix of reconstructed coefficients of level `N`, based on the wavelet decomposition structure `[C,S]` (see `wavedec2` for more information).

`'wname'` is a string containing the name of the wavelet (see `wfilters` for more information). If `'type'` ```= 'a'```, approximation coefficients are reconstructed; otherwise if `'type'` `= 'h'` (`'v'` or `'d'`, respectively), horizontal (vertical or diagonal, respectively) detail coefficients are reconstructed.

Level `N` must be an integer such that `0``N``size(S,1)-2` if `'type'` ```= 'a'``` and such that `1`` N `` size(S,1)-2` if `'type'` ```= 'h'```, `'v'`, or `'d'`.

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

For `X = wrcoef2('type',C,S,Lo_R,Hi_R,N)`, `Lo_R` is the reconstruction low-pass filter and `Hi_R` is the reconstruction high-pass filter.

`X = wrcoef2('type',C,S,'wname')` or ```X = wrcoef2('type',C,S,Lo_R,Hi_R)``` reconstruct coefficients of maximum level `N = size(S,1)-2`.

## Examples

```% The current extension mode is zero-padding (see dwtmode). % Load an image. load woman; % X contains the loaded image. % Perform decomposition at level 2 % of X using sym5. [c,s] = wavedec2(X,2,'sym5'); % Reconstruct approximations at % levels 1 and 2, from the wavelet % decomposition structure [c,s]. a1 = wrcoef2('a',c,s,'sym5',1); a2 = wrcoef2('a',c,s,'sym5',2); % Reconstruct details at level 2, % from the wavelet decomposition % structure [c,s]. % 'h' is for horizontal, % 'v' is for vertical, % 'd' is for diagonal. hd2 = wrcoef2('h',c,s,'sym5',2); vd2 = wrcoef2('v',c,s,'sym5',2); dd2 = wrcoef2('d',c,s,'sym5',2); % All these images are of same size sX. sX = size(X) sX = 256 256 sa1 = size(a1) sa1 = 256 256 shd2 = size(hd2) shd2 = 256 256 ```

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### Tips

If `C` and `S` are obtained from an indexed image analysis (respectively a truecolor image analysis) then `X` is an `m`-by-`n` matrix (respectively an `m`-by-`n`-by-3 array).

For more information on image formats, see the reference pages of `image` and `imfinfo` functions.