hvanalysis.m

一些个 人收集的小波变换的程序

% 
% wavelet analysis of a image region
% h0: 	analysis lowpass	h1: analysis highpass
% Ain: 	input image [M x N]
%      	[sr, sc] and [er, ec]  specify the rect region of Ain
%      	to be decomposed. 
% diret:horizontal =1 vertical = -1;	
% A: output images, only the region is changed
%
%  function [A]=hvanalysis(h0, h1, Ain, sr, sc, er, ec, diret)
%



function [A]=hvanalysis(Ain,sr,sc,er,ec,diret)
h0=[0.037828, -0.023849, -0.110624, 0.377402, 0.852699, 0.377402, -0.110624, -0.023849, 0.037828]  ;
h1=[0.064539, -0.040689,-0.418092, 0.788486, -0.418092, -0.040689, 0.064539];

RRM=(sr+er-1)/2;
CCM=(sc+ec-1)/2;

if ( diret >0),

% 	disp('	horizontal analysis .....');
	for rn=sr:er,
		lowpart=filterdown(h0, Ain(rn,sc:ec),0);
		highpart=filterdown(h1, Ain(rn, sc:ec),1);
		Ain(rn, sc:CCM)=lowpart;
		Ain(rn, (CCM+1):ec)=highpart;
	end
else

% 	disp('	vertical analysis .....');
	for cn=sc:ec,
		lowpart=filterdown(h0, Ain(sr:er, cn),0);
		highpart=filterdown(h1, Ain(sr:er, cn),1);
		Ain(sr:RRM, cn)=lowpart;
		Ain((RRM+1):er, cn)=highpart;
	end
end

A=Ain;



%-------------filterdown-------------

function y=filterdown(B, x, flag)

	yt=mfilter(B, x);
	N=length(yt);
	y=yt((1+flag):2:N);
return;


% ------------mfilter function

function [y]=mfilter(B, x)

len=length(x);
y=zeros(1, len);

[RN CN]=size(x);
if CN==1,
	x=x';
end

flen=length(B);

xe=[ fliplr(x(2:len)), x, fliplr( x(1:(len-1)))];

dd=(flen-1)/2;
yt=filter(B,1, xe);
y=yt( (len+dd):(len+len-1+dd));
if CN==1,
	y=y';
end

return;