ridge_awt.sci

小波分解源代码

function localmaxima = Ridge_AWT(m,par,ABS)
// Ridge_AWT -- Ridges of an Analytic Wavelet Transform
//  Usage
//    localmaxima = Ridge_AWT(m,par,ABS);
//  Inputs
//    m       	  input matrix
//    par    	  parameter, 2*par is how many neighbours to compare
//    ABS	  flag, compare by absolute value(1) or not(0)
//  Outputs
//    localmaxima  local maxima of every column, binary matrix same size
//		  as m.
//  Description
//    see section 4.4.2 of Mallat's book
//  Algorithm
//    Get the local maxima first, then compare with original value
//  References
// 
//  Copyright Aldo I Maalouf 
 
 [lhs,rhs]=argn();
 if rhs < 3, 
	ABS = 1;
 end;
 
 if rhs < 2,

 end;
 
 if ABS,
	m = abs(m);
 end;

 [nrows,ncols] = size(m);
 localmaxima   = zeros(nrows,ncols);


 t      = 1:nrows;
 tplus  = rshift(t);
 tminus = lshift(t);
Thresh = max(max(abs(m)))/20;

        c1=ones(nrows,ncols);
	c2=ones(nrows,ncols);
	c3=ones(nrows,ncols);
 for i = 1:ncols,
 	x = ShapeAsRow(m(:,i));
	for j = 1:par,
		x = max(x(t), x(tplus), x(tminus));
	end;
	x = ShapeAsRow(x)';
	thresh = max(x)/2;
	
    for j=1:nrows,
	if m(j,i)<x(j,1),
	    c1(j,i)=0;	
	end
	
	if  m(j,i)<=thresh,
	    c2(j,i)=0;  	 
	end
	
	if m(j,i)<=Thresh,
	    c3(j,i)=0;    
	end
    end
       localmaxima(:,i) = c1(:,i).*c2(:,i).*c3(:,i);
	//localmaxima(:,i) = (~(m(:,i)<x)).*(m(:,i)>thresh).*(m(:,i)>Thresh);
 end;
 endfunction