lwt

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Aseel H 2011-12-31

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https://ww2.mathworks.cn/matlabcentral/answers/25044-lwt

 if I use lwt2()for multi level as: 
X_InPlace = lwt2(X,W,LEVEL,'typeDEC',typeDEC) 
What refers to the 'typeDEC',typeDEC? 
and how separate the subbands as cA,cH,cV,cD for each level?

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Answer 1

Wayne King 2011-12-31

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Hi Aseel, Glad to see you are using the lifting utilities in the Wavelet Toolbox, they're definitely powerful.

'typeDEC' takes the value 'w' or 'wp'. 'w' gives you a wavelet subband filtering, while 'wp' gives you a wavelet packet tree.

If you use X_InPlace, you can separate the coefficients as follows.

          CA = X_InPlace(1:2:end,1:2:end)
          CH = X_InPlace(2:2:end,1:2:end)
          CV = X_InPlace(1:2:end,2:2:end)
          CD = X_InPlace(2:2:end,2:2:end)

For example:

       load woman;
       X_InPlace = lwt2(X,'bior3.5',1,'typeDEC','w');
       CA = X_InPlace(1:2:end,1:2:end);
       CH = X_InPlace(2:2:end,1:2:end);
       CV = X_InPlace(1:2:end,2:2:end);
       CD = X_InPlace(2:2:end,2:2:end);