I used to think look past just means ignore until I heard this sentence used by an American talking about a picture saying,
"If you look past the picture, you can see a horse."
I gave it an online search and the related pages show hidden 3D pictures. I can tell then the picture he was talking about was one of these. The thing I'm not clear about is how you do it. How do you look past a picture exactly? Is it making the picture closer to your eyes or vice versa? Is it looking at the picture from sides? or something else?!