normalizef.m

Sparse Signal Representation using Overlapping Frames (matlab toolbox)

function [F,varargout]=NormalizeF(F,G)
% NormalizeF   Normalize the synthesis vectors in frame F
%
% F=NormalizeF(F);    
% [F,nf]=NormalizeF(F,G);     
%-----------------------------------------------------------------------------------
% arguments:
%   F      the frame, a NxKxP matrix or a Qx1 vector
%          as input argument it is "unnormalized" values
%          as output argument it is "normalized" values
%   G      the mapping matrix, size NxKxP if F is a Qx1 vector, else G=[]
%          or G may be omitted
%   nf     the normalization factors, for each of the K synthesis vectors
%          in the frame the frame vector is updated like: F(:,k)=F(:,k)/nf(k);
%-----------------------------------------------------------------------------------

%----------------------------------------------------------------------
% Copyright (c) 2001.  Karl Skretting.  All rights reserved.
% Hogskolen in Stavanger (Stavanger University), Signal Processing Group
% Mail:  [e-mail]   Homepage:  http://www.ux.his.no/~karlsk/
% 
% HISTORY:  dd.mm.yyyy
% Ver. 1.0  04.10.2001  KS: function made
% Ver. 1.1  25.11.2002  KS: moved from ..\Frames to ..\FrameTools
%----------------------------------------------------------------------

Mfile='NormalizeF';

if (nargin<1)
   error([Mfile,': wrong number of arguments, see help.']);
end
if (nargin<2); G=[]; end;

if length(G)==0
   [N,K,P]=size(F);
   Fb=F;
   Q=0;
else
   [N,K,P]=size(G);
   Q=length(F);
   Fb=BuildFg(F,G);
end
if P>1
   % reshape frame into K vectors of length NP
   Fb=reshape(permute(Fb,[1,3,2]),N*P,K);
end

% normalize each of these
nf=ones(K,1);
for k=1:K;    % now normalize Fb
   temp=Fb(:,k)'*Fb(:,k);
   if (temp > 0); nf(k)=sqrt(temp); end;
   if sum(Fb(:,k))<0; nf(k)=-nf(k); end;
   Fb(:,k)=Fb(:,k)/nf(k);
end
if P>1
   %  rearrange Fb into size NxKxP
   Fb=permute(reshape(Fb,N,P,K),[1,3,2]);
end
% now find F from G and Fb (or only from Fb)
if Q==0
   F=Fb;
else
   for q=1:Q
      I=find(G(:)==q);
      F(q)=Fb(I(1));
   end
end

if nargout==2
   varargout(1)={nf};
end

return