I_rgb = imread('lena.jpg'); %subplot(2, 2, 1), imshow(I_rgb), title('lena-rgb') I_gray = rgb2gray(I_rgb); %subplot(2, 2, 2), imshow(I_gray), title('lena-gray') I = imresize(I_gray, 0.25); %subplot(2, 2, 3), imshow(I), title('lena-qtr') fid = fopen('./lena.txt','wt');