nonlinearenhancement.m

学习二进小波变换用于图像增强

% IEEE Image Processing, vol.9, No.6, 2000. 

%--------- 滤波器对图像作增强提高视觉质量－－－－－－－

clear all;
C=double(imread('t1.bmp'));%cameraman.tifSAR01.bmpBARB.BMP;5-51fft6649-060-1.tifmed01.jpg
h=[1,1,1;1,1,1;1,1,1]./9;
B=C(:,:,1);
%B=imfilter(B,h,'replicate');
S=size(B);H=S(1,1);W=S(1,2);

%%%%%%%%%%%%%%%%% CDF9/7
t=0.75;%0.730174;
h0 = (8*t*t*t-6*t*t+3*t)/(1+2*t)*(1/32);
h1 = (-16*t*t*t+20*t*t-12*t+3)/(1+2*t)*(1/32);
h2 = (2*t-3)/(1+2*t)*(1/8.);
h3 = (16*t*t*t-20*t*t+28*t+5)/(1+2*t)*(1/32.);
h4 = (-8*t*t*t+6*t*t+5*t+20)/(1+2*t)*(1/16.);
hL=[h0,h1,h2,h3,h4,h3,h2,h1,h0];

g0=-t/16;
g1=(1-2*t)/16;
g2=(t+4)/16;
g3=(3+2*t)/8;
hH=[-g0,g1,-g2,g3,-g2,g1,-g0];
%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%  对淹没在噪声中的SAR图像首先用Wiener滤波法自适应去噪
%Idenoise= medfilt2(B(:,:,1),[3 3]);%中值滤波
%Idenoise = wiener2(B(:,:,1),[5 5]);%自适应滤波
%Idenoise=double(Idenoise);
Idenoise=B;%imresize(B,[512,510]);

% 用多分辨分解法提取高频边缘BI

hL=[1/16,1/4,3/8,1/4,1/16];
for i=1:length(hL)
    for j=1:length(hL)
        hL2D(i,j)=hL(i)*hL(j);
    end
end
L0=imfilter(Idenoise,hL2D,'replicate');%低频近似图像L0
L0=double(L0);
L0max=max(max(L0));
c=0.3;s=2;
T1 = 0;
T2 = (1-c)*L0max;
k1=0.6; k2=s;

BI = Idenoise-L0;% 第一层高频边缘BI

 % 对BI作非线性插值后得到newBI
newBI=BI;

for i=1:H
    for j=1:W
        if abs(BI(i,j))<=T1
            newBI(i,j)=k1*BI(i,j);
        else if (abs(BI(i,j))>T1)&(abs(BI(i,j))<=T2)
                newBI(i,j)=sign(BI(i,j))*(k2*abs(BI(i,j))+T1*(k1-k2));
            end
        end
    end
end
%newBI=s*newBI;

% 对newBI作高通滤波得到增强后的高频边缘BI
hH=[-1/16,1/4,-3/8,1/4,-1/16];%[-1,2,-1]/2;
for i=1:length(hH)
    for j=1:length(hH)
        hH2D(i,j)=hH(i)*hH(j);
    end
end

BI=imfilter(newBI,hH2D,'replicate');%修正后的边缘
%BI=newBI-double(imfilter(newBI,hL2D,'replicate'));

BI=double(BI);
Irecover=newBI+L0;

for i=1:H
    for j=1:W
        if Irecover(i,j)<0
            Irecover(i,j)=0;
        else if Irecover(i,j)>255
                Irecover(i,j)=255;
            end
        end
    end
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
EP1D=[-0.15,0.25,0.7,0.25,-0.15];
%EP1D=[-0.05,0.15,-0.25,0.3,0.9,0.3,-0.25,0.15,-0.05]./1.2
for i=1:length(EP1D)
    for j=1:length(EP1D)
        EP2D(i,j)=EP1D(i)*EP1D(j);
    end
end
Irepro = imfilter(Irecover,EP2D,'replicate');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%figure,imshow((100*BI)./255,[]);%imfilter(B,hH2D,'replicate')

figure,imshow(uint8(B),[]);
title('原图');
%subplot(122);
figure,imshow(uint8(Irecover),[]);
title(['高频非线性增强后的图像']);

figure,imshow(uint8(Irepro),[]);
title(['非线性增强后再补偿的图像']);