Focusing at a point behind the image is exactly what we've always done for every other magic eye poster because it only requires relaxing your eyes (staring off into the distance) for the image to pop into focus. Cross eyed viewing is damn near impossible on any screen at less than an arm's length away without significant eye strain or external devices (like the stereoscopic viewers that photogrammetrists would use to view these kinds of images without inducing a migraine) and since the dot is on top holding a finger up as a guide ends up obstructing the entire view unless your arms are growing out of your forehead. The wall eyed view has none of these issues.

I appreciate the post and your effort. But, the images themselves are frustrating and have killed my initial reaction, which was to share them further. Because I'm nearly the only person I know that wouldn't loose interest in the explanation for "correct viewing" half way through. If they were wall eyed stereoscopic images, I could just say "Magic Eye", they'd remember Mallrats, see the schooner, and go "Ooh neat."