Two Dimensional Gravity Optical Illusion

I've seen this illusion around the net and it seems to me that the red lines in this image must be effected by the gravitational pull of the circles. Normally 2 dimensional pictures don't have that strong a gravitational field but this image must use special high mass color in the center of these circles, how else could we explain the way the straight lines are pulled off center.



I just checked and the lines are actually straight. I guess the gravity of the special color must be effecting the way we see these lines, almost as if an optical illusion is causing us to view straight lines as wavy lines.

What am I saying the title of this site is Optical Illusions Etc..., so of course this is another optical illusion that causes us to view straight lines as curved lines.

Check out this site to see this illusion with and without the circles, just move your mouse over the orange bar at the bottom.