function [out] = lap(Img)
F = rgb2gray(Img);
[m,n]=size(F);
G=zeros(m,n);
%H=zeros(m,n);
w=[0,-1,0;-1,4,-1;0,-1,0];
for x=1:m
for y=1:n
if (x==1||y==1||x==m||y==n)
G(x,y)=F(x,y);
else
G(x,y)=w(1,1)*F(x-1,y-1)+w(1,2)*F(x-1,y)+w(1,3)*F(x-1,y+1)...
+w(2,1)*F(x,y-1)+w(2,2)*F(x,y)+w(2,3)*F(x,y+1)...
+w(3,1)*F(x+1,y+1)+w(3,2)*F(x+1,y)+w(3,3)*F(x+1,y+1);
end
end
end
out=uint8(G);