Wavelet Toolbox™

Inverse 2-D lifting wavelet transform

Syntax

• X = ilwt2(AD_In_Place,W)
  X = ilwt2(CA,CH,CV,CD,W)
  X = ilwt2(AD_In_Place,W,LEVEL)
  X = ilwt2(CA,CH,CV,CD,W,LEVEL)
  X = ilwt2(AD_In_Place,W,LEVEL,'typeDEC',typeDEC)
  X = ilwt2(CA,CH,CV,CD,W,LEVEL,'typeDEC',typeDEC)
  

Description

ilwt2 performs a 2-D lifting wavelet reconstruction with respect to a particular lifted wavelet that you specify.

X = ilwt2(AD_In_Place,W) computes the reconstructed matrix X using the approximation and detail coefficients matrix AD_In_Place, obtained by a lifting wavelet decomposition. W is a lifted wavelet name (see liftwave).

X = ilwt2(CA,CH,CV,CD,W) computes the reconstructed matrix X using the approximation coefficients vector CA and detail coefficients vectors CH, CV, and CD obtained by a lifting wavelet decomposition.

X = ilwt2(AD_In_Place,W,LEVEL) or X = ILWT2(CA,CH,CV,CD,W,LEVEL) computes the lifting wavelet reconstruction, at level LEVEL.

X = ilwt2(AD_In_Place,W,LEVEL,'typeDEC',typeDEC) or X = ilwt2(CA,CH,CV,CD,W,LEVEL,'typeDEC',typeDEC) with typeDEC = 'w' or 'wp' computes the wavelet or the wavelet packet decomposition using lifting, at level LEVEL.

Instead of a lifted wavelet name, you may use the associated lifting scheme LS: X = ilwt2(...,LS,...) instead of X = ilwt2(...,W,...).

For more information about lifting schemes, see lsinfo.

Remarks

If AD_In_Place or cA,cH,cV,cD are obtained from an indexed image analysis or a truecolor image analysis, they are m-by-n matrices or m-by-n-by-3 arrays, respectively.

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

Examples

• % Start from the Haar wavelet and get the
  % corresponding lifting scheme.
  lshaar = liftwave('haar');
  
  % Add a primal ELS to the lifting scheme.
  els = {'p',[-0.125 0.125],0};
  lsnew = addlift(lshaar,els);
  
  % Perform LWT at level 1 of a simple image.
  x = reshape(1:16,4,4);
  [cA,cH,cV,cD] = lwt2(x,lsnew);
  
  % Perform integer LWT of the same image.
  lshaarInt = liftwave('haar','int2int');
  lsnewInt = addlift(lshaarInt,els);
  [cAint,cHint,cVint,cDint] = lwt2(x,lsnewInt);
  
  % Invert the two transforms.
  xRec = ilwt2(cA,cH,cV,cD,lsnew);
  err = max(max(abs(x-xRec)))
  
  err =
  
       0
  
  xRecInt = ilwt2(cAint,cHint,cVint,cDint,lsnewInt);
  errInt = max(max(abs(x-xRecInt)))
  
  errInt =
  
       0    
  

See Also
lwt2

Provide feedback about this page

ilwt

ind2depo

© 1984-2008- The MathWorks, Inc.    -   Site Help   -   Patents   -   Trademarks   -   Privacy Policy   -   Preventing Piracy   -   RSS