pkg load image

clear
clc

I = imread('Lena256color.jpg');
I2 = I;

for i = 1 : 256
  for j = 1 : 256
    for k = 1 : 3
      myRand = rand/2-0.25;
      I2(i,j,k) = I(i,j,k) + myRand * double(I(i,j,k));
    endfor
  endfor
endfor
clear i, j, k
Idiff = uint8(abs(double(I2) - double(I)));

numSame = 0;
for i = 1 : 256
  for j = 1 : 256
    if (Idiff(i,j,1)==0 && Idiff(i,j,2)==0 && Idiff(i,j,3)==0)
      numSame = numSame + 1;
    endif
  endfor
endfor

H = (1/25) * ones(5);

I2AVGfiltRed = imfilter(I2(:,:,1), H);
I2AVGfiltGreen = imfilter(I2(:,:,2), H);
I2AVGfiltBlue = imfilter(I2(:,:,3), H);

I3 = uint8(zeros(256,256,3));
I3(:,:,1) = I2AVGfiltRed;
I3(:,:,2) = I2AVGfiltGreen;
I3(:,:,3) = I2AVGfiltBlue;

I2MEDfiltRed = ordfilt2(I2(:,:,1), 13, ones(5));
I2MEDfiltGreen = ordfilt2(I2(:,:,2), 13, ones(5));
I2MEDfiltBlue = ordfilt2(I2(:,:,3), 13, ones(5));

I4 = uint8(zeros(256,256,3));
I4(:,:,1) = I2MEDfiltRed;
I4(:,:,2) = I2MEDfiltGreen;
I4(:,:,3) = I2MEDfiltBlue;

psnrAVG = psnr(I3, I2, 255);
psnrMED = psnr(I4, I2, 255);

subplot(2,3,1), imshow(I,[0 255]), title('Original')
subplot(2,3,2), imshow(I2,[0 255]), title('Randomized')
subplot(2,3,3), imshow(Idiff,[]), title('Difference image')
subplot(2,3,4), imshow(I3,[0 255]), title('AVG filtered')
subplot(2,3,5), imshow(I4,[0 255]), title('MED filtered')