fwt_pb.sci

小波分解源代码

function wcoef = FWT_PB(x,L,qmf,dqmf)
// FWT_PB -- Forward Wavelet Transform (periodized, biorthogonal)
//  Usage
//    wc = FWT_PB(x,L,qmf,dqmf)
//  Inputs
//    x      1-d signal; length(x) = 2^J
//    L      Coarsest Level of V_0;  L << J
//    qmf    quadrature mirror filter (symmetric)
//    dqmf   quadrature mirror filter (symmetric, dual of qmf)
//  Outputs
//    wc     1-d wavelet transform of x.
//
//  Description
//    1. qmf filter may be obtained from MakeBSFilter   
//    2. usually, length(qmf) < 2^(L+1)
//    3. To reconstruct use IWT_PB
//
//  See Also
//    IWT_PB, MakeBSFilter
//
//  Copyright Aldo I Maalouf

  [n,J] = dyadlength(x) ;
  wcoef = zeros(1,n) ;
  beta = ShapeAsRow(x);  //take samples at finest scale as beta-coeffts
  for j=J-1:-1:L
       alfa = DownDyadHi_PBS(beta,dqmf);
       wcoef(dyad(j)) = alfa;
       beta = DownDyadLo_PBS(beta,qmf) ;  
  end
  wcoef(1:(2^L)) = beta;
  wcoef = ShapeLike(wcoef,x);

endfunction