upwlev2

Purpose

Single-level reconstruction of 2-D wavelet decomposition

Syntax

• [NC,NS,cA] = upwlev2(C,S,'wname')
  [NC,NS,cA] = upwlev2(C,S,Lo_R,Hi_R)
  

Description

upwlev2 is a two-dimensional wavelet analysis function.

[NC,NS,cA] = upwlev2(C,S,'wname') performs the single-level reconstruction of wavelet decomposition structure [C,S] giving the new one [NC,NS], and extracts the last approximation coefficients matrix cA.

[C,S] is a decomposition at level n = size(S,1)-2, so [NC,NS] is the same decomposition at level n-1 and cA is the approximation matrix at level n.

'wname' is a string containing the wavelet name, C is the original wavelet decomposition vector, and S the corresponding bookkeeping matrix (for detailed storage information, see wavedec2).

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

For [NC,NS,cA] = upwlev2(C,S,Lo_R,Hi_R), Lo_R is the reconstruction low-pass filter and Hi_R is the reconstruction high-pass filter.

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 db1. 
  [c,s] = wavedec2(X,2,'db1');
  sc = size(c)
  
  sc =
      1   65536
  
  val_s = s 
  
  val_s =
      64   64 
      64   64 
      128  128 
      256  256
  
  % One step reconstruction of wavelet 
  % decomposition structure [c,s]. 
  [nc,ns] = upwlev2(c,s,'db1');
  snc = size(nc)
  
  snc =
      1   65536
  
  val_ns = ns
  
  val_ns =
      128   128 
      128   128 
      256   256
  

See Also

idwt2, upcoef2, wavedec2

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