Documentation

This is machine translation

Translated by Microsoft
Mouse over text to see original. Click the button below to return to the English verison of the page.

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 containing the name of 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);

More About

collapse all

Algorithms

See upcoef.

See Also

Introduced before R2006a

Was this topic helpful?