iwt2_sbs.sci

小波分解源代码

function x = IWT2_SBS(wc,L,qmf,dqmf)
// IWT2_SBS -- Inverse 2d Wavelet Transform
//            (symmetric extention, bi-orthogonal)
//  Usage
//    x = IWT2_SBS(wc,L,qmf,dqmf)
//  Inputs
//      wc    2-d wavelet transform [n by n array, n arbitrary]
//      L     coarse level
//      qmf   low-pass quadrature mirror filter
//      dqmf  high-pas dual quadrature mirror filter
//  Outputs
//      x     2-d signal reconstructed from wc
//  Description
//      If wc is the result of a forward 2d wavelet transform, with
//           wc = FWT2_SBS(x,L,qmf,dqmf)
//      then x = IWT2_SBS(wc,L,qmf,dqmf) reconstructs x exactly if qmf is a nice
//      quadrature mirror filter, e.g. one made by MakeBioFilter
//  Copyright Aldo I Maalouf

[m,J] = dyadlength(wc(:,1));
[n,K] = dyadlength(wc(1,:));
// assume m==n, J==K

x = wc;

dpm = dyadpartition(m);

for jscal=L:J-1,
    bot = 1:dpm(jscal+1);
    top = (dpm(jscal+1)+1):dpm(jscal+2);
    all = [bot top];

    nc = length(all);

    for iy=1:nc,
        x(all,iy) =  UpDyad_SBS(x(bot,iy)', x(top,iy)', qmf, dqmf)';
    end
    for ix=1:nc,
        x(ix,all) = UpDyad_SBS(x(ix,bot), x(ix,top), qmf, dqmf);
    end
end
endfunction