function myline(f,percent)
figure(1)
imshow(f);
ff=double(f);
w = [2 -1 -1; -1 2 -1; -1 -1 2];
g=imfilter(ff, w);
figure(2), imshow(g, [ ]);
 gtop=g(1:126, 1:126);
 gtop=pixeldup(gtop, 4);
figure(3); imshow(gtop, [ ]);
gbot=g(end-125:end, end-125:end);
gbot=pixeldup(gbot, 4);
figure(4); imshow(gbot, [ ]);
g=abs(g);
figure(5), imshow(g, [ ]);
T=max(g(:));
g = g>=percent*T;
figure(6), imshow(g)