Keep trying. Here is a good explanation of the phenomenon: https://en.wikipedia.org/wiki/Autostereogram
. Near the bottom, this article has a super picture of chessboard that just jumps out in 3D when you look at it properly. Basically you trick your eyes into viewing an image stereoscopically. If you have ever succcessfully tried to see a pair of stereoscopic images in 3D without a viewer, the technique is similar.