Adding Noise to an Original Image

 Lenna = imread('Lenna2.jpg');

 SPNoiseLenna = imnoise(Lenna,'salt & pepper',0.07);

 GNoiseLenna = imnoise(Lenna,'gaussian',0.01,0.005);

 PNoiseLenna = imnoise(Lenna,'poisson');

 SNoiseLenna = imnoise(Lenna,'speckle',0.06);

 subplot(2,2,1); imshow(SPNoiseLenna);  title('Salt & Pepper Noise');

 subplot(2,2,2); imshow(GNoiseLenna);   title('Gaussian Noise');

 subplot(2,2,3); imshow(PNoiseLenna);   title('Poisson Noise');

 subplot(2,2,4); imshow(SNoiseLenna);   title('Speckle Noise');