The size of this image is making it a little weird. This one was clearly designed to be a full-sized poster, and unless you’re viewing the image on a very large display, it kinda pushes the amount of convergence that your eyes have to do into the slightly-too-small range.
That means you’re likely adjusting your eyes to a point that doubles the correct convergence distance, and you’re getting a garbled image.
Even when you do get it to appear correctly, the too-small size will make the illusion of depth somewhat less effective than it would be if you were looking at it, in the intended scale.
EDIT: The source for this knowledge = every book about stereograms that I could ever find. Which was weirdly only a couple that actually discussed how they work, rather than just having a bunch of them printed. But I was legit OBSESSED with stereograms, back in the 90s. I read about them the way a kid who suddenly grows past 6’4" suddenly starts reading about basketball.
The size of this image is making it a little weird. This one was clearly designed to be a full-sized poster, and unless you’re viewing the image on a very large display, it kinda pushes the amount of convergence that your eyes have to do into the slightly-too-small range.
That means you’re likely adjusting your eyes to a point that doubles the correct convergence distance, and you’re getting a garbled image.
Even when you do get it to appear correctly, the too-small size will make the illusion of depth somewhat less effective than it would be if you were looking at it, in the intended scale.
EDIT: The source for this knowledge = every book about stereograms that I could ever find. Which was weirdly only a couple that actually discussed how they work, rather than just having a bunch of them printed. But I was legit OBSESSED with stereograms, back in the 90s. I read about them the way a kid who suddenly grows past 6’4" suddenly starts reading about basketball.