These are easier for me than normal Magic Eye pictures, because I can just use the "floating hotdog"* method of putting it right up to my face, letting my eyes get used to being focused there and then slowly moving away from it until it pops out of the page/screen.
*(to do the "floating hotdog" trick, put your index fingers end to end then put them right up in your eye line. Now slightly move your fingers apart until the floating hotdog appears)