upcoef2 (Wavelet Toolbox)

Direct reconstruction from 2-D wavelet coefficients.

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,Lo_R,Hi_R)

Description

upcoef2 is a two-dimensional wavelet analysis function.

Y = upcoef2(O,X,'wname',N,S) computes the N steps reconstructed coefficients of matrix X and takes the central part of size S. 'wname' is a string containing the name of the wavelet.

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), Lo_R 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) return 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

% 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);

Algorithm

See upcoef.