ch3=softt(h3,thr1 clear

clc

I=imread( lena512.bmp )

imshow(I)

I=double(I)

II=I+30*randn(size(I))

figure

imshow(II,[])

[a1,h1,v1,d1]=dwt2(II, sym8 )

[a2,h2,v2,d2]=dwt2(a1, sym8 )

[a3,h3,v3,d3]=dwt2(a2, sym8 )



sigma=median(abs(d1(:)))/0.6745

x=3*sigma

thr1=x*2^(-1) thr2=x*2^(-0.5) thr3=x 小波图像去噪- ch3=softt(h3,thr1 clear

clc

I=imread( lena512.bmp )

imshow(I)

I=double(I)

II=I+30*randn(size(I))　

figure

imshow(II,[])

[a1,h1,v1,d1]=dwt2(II, sym8 )

[a2,h2,v2,d2]=dwt2(a1, sym8 )

[a3,h3,v3,d3]=dwt2(a2, sym8 )



sigma=median(abs(d1(:)))/0.6745　

x=3*sigma

thr1=x*2^(-1) thr2=x*2^(-0.5) thr3=x