% 中值濾波—讀取圖象文件

i_source=imread('d:\lena.bmp');

[height,width]=size (i_source);

I=imnoise(i_source,'salt & pepper',0.01);
I=im2double(I);
imwrite(I,'noise.bmp');
bmpTemp=I;
I1=I;
Temp=zeros(3);
%figure,imshow(I);


% 橫向一維中值濾波, 周圍3個點取中值
for i=2:height-1
for j=2:width-1
Temp(1)=bmpTemp(i,j-1);
Temp(2)=bmpTemp(i,j);
Temp(3)=bmpTemp(i,j+1);

Count=Temp(1);
for k=1:3
if Temp(k)>Count
Temp(1)=Temp(k);
Temp(k)=Count;
Count=Temp(1);
end
end
I1(i,j)=Temp(2);
end
end
%figure,imshow(I1);


% 縱向一維中值濾波, 周圍3個點取中值
I2=I1; 
for i=2:height-1
for j=2:width-1
Temp(1)=I1(i-1,j);
Temp(2)=I1(i,j);
Temp(3)=I1(i+1,j);

Count=Temp(1);
for k=1:3
if Temp(k)>Count
Temp(1)=Temp(k);
Temp(k)=Count;
Count=Temp(1);
end
end
I2(i,j)=Temp(2);
end
end

% 顯示處理結果
subplot(1,3,1)
imshow(i_source);
title('原圖象');
subplot(1,3,2)
imshow(I)
title('噪聲圖像')
subplot(1,3,3)
imshow(I2)
title('中值濾波平滑')