Mask1D = [-29/256 0 88/256 138/256 88/256 0 -29/256]; 
Mask2D = Mask1D'*Mask1D; 

lena = imread('lena.pgm');

lena2=conv2(lena,Mask2D);

figure(1);
imshow(lena);

figure(2);
imshow(uint8(lena2));

lena3=conv2(lena,Mask1D);
lena4=conv2(lena,Mask1D');

figure(3);
imshow(uint8(lena3));
figure(4);
imshow(uint8(lena4));