laplacian.m

a=imread('Fig3.40(a).jpg');
a=double(a);
b=[-1 -1 -1;-1 8 -1;-1 -1 -1];
y=spatialfilt(a,b);
imshow(a,[]);
title('original');
figure
imshow(y,[]);
title('filtered image');
figure
x=a+y;
imshow(x,[]);
title('sharpened image');