I=imread(‘lena.png’);
[rows, cols, channels] = size(I);
I_gray=rgb2gray(I);
I_gray_max=max(I_gray(:));
I_gray_min=min(I_gray(:));
I_filt=imgaussfilt(I_gray);
figure(1)
imshow(I_filt)
figure(2)
imshow(I_gray)
figure(3)
I_filt_sigma=imgaussfilt(I_gray,3);
imshow(I_filt_sigma)