wt07fig06.m

一些关于小波的去噪算法

% CAPTION :
fprintf('\n');
disp('Figure 7.6')
disp('The modulus squared of the Fourier transform of a cubic') 
disp('spline wavelet is dilated by 2^j, for 0 < j < 6.')

close all;
N = 4096;
M = 80;
omega = ((1:N)/N -.5) * 2 * M;
omega(N/2) = omega(N/2+1)/100;
hatpsi =sqrt(Sigma8(omega./2+pi)./(Sigma8(omega./2).*Sigma8(omega)));
hatpsi = hatpsi .* exp(-i.*omega./2) ./ (omega).^4;

[def,psi] = NormedIFFT(hatpsi,2*M);
supp = find(abs(hatpsi) > max(abs(hatpsi)) ./1000);
defmax = max(def(find(abs(hatpsi) == max(abs(hatpsi)))));
def = def .*pi./defmax;

clf;
plot(def(supp),abs(hatpsi(supp)).^2);
hold on
plot(def(supp)./2,abs(hatpsi(supp)).^2);
hold on
plot(def(supp)./4,abs(hatpsi(supp)).^2);
hold on
plot(def(supp)./8,abs(hatpsi(supp)).^2);
hold on
plot(def(supp)./16,abs(hatpsi(supp)).^2);

axis([-pi pi 0 1.1]);

% Written by Maureen Clerc and Jerome Kalifa, 1997
% [e-mail], [e-mail]


    
    
    
 
 
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