Below pictures are of white papers. As I turned the camera on auto and didn’t correct, the papers turn out mid-gray. The only obvious place I can think of would be precisely in the center. The point is easy to see: unobstructed, the background is plain, the point is dark and the background light. The point is always in relation to frame (and background). Which is logic. A position has to be measured from a constant. The further away from the frame, the less obvious the relation becomes.
The way my eyes scan the surface