wrcoef2 (Wavelet Toolbox)

Reconstruct single branch from 2-D wavelet coefficients.

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).

'wname' is a string containing the name of the wavelet. 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) reconstructs coefficients of maximum level N = size(S,1)-2.

Examples

% Load original 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