%圖像加噪
I = imread('LENA256.bmp');
J1 = imnoise(I,'salt & pepper',0.02);
subplot(2,2,1);imshow(J1);title('salt & pepper noise');
J2 = imnoise(I,'gaussian',0.02);
subplot(2,2,2);imshow(J2);title('gaussian noise');
J3 = imnoise(I,'poisson');
subplot(2,2,3);imshow(J3);title('poisson noise');
J4 = imnoise(I,'speckle');
subplot(2,2,4);imshow(J4);title('speckle noise');