You are correct, there is nothing to see. It’s all a con along the lines of the Emperor’s New Clothes. Just be like me and pity the poor people who have to pretend there is something to see.
I wish more of these were cross eye viewed instead of un-cross eye viewed. Crossing my eyes is simple and it’s easy to see the picture in focus, but un-crossing them is difficult, and they refuse to focus on the image afterwards, and once I’m done looking at them I see everything else blurry.
Is it really easier for most people to see the un-crossed ones?
You’re joking right, don’t ask?
But, you’re not the first person to say this, I had one particularly bizarre , um, conversation, with an acquaintance who held exactly your stated position.
It’s all in the mind’s eye, admitted, but that the stereogram effect is real, measurable, and to those who can see them universal (tch! I’m oxymoronicising all over the place nowadays) is not in doubt.
I can’t make them work for me. Ever. Reason is that my eyes are slightly naturally squinted, I look out of one or the other, never both at the same time. I never could see in 3-d, I have to use parallax to judge distances. So my eyes can’t see those images as 3-d, no matter how hard I try =p
Upshot is, if I lost an eye I wouldn’t be as disadvantaged as most people 
>> I never could see in 3-d, I have to use parallax to judge distances
This is a contradiction. Parallax is what gives us a sense of depth perception and precisely why those things work.
Another factor which may come into play is how dominant one eye is over the other. When I was playing with the referenced graphic to place the arrows I noticed my right eye dominates over the left. I am thinking people with weak eye dominance would have it easier than people who have one eye very strongly dominant over the other.
>> It’s a sailboat
>> It’s a schooner
Actually, it’s a stinkpot. 
This may be it. My left eye has such a bad astigmatism that it may as well not even be there. My right eye is so dominant that if I cover my left eye, my field of view does not really change.
I knew there was a physiological aspect to all of this.
I’ve also never managed to see one of these things, but in my case it’s my left eye that is dominant. I think that, on following the instructions, I managed to get a ghost of a teapot shape, but I may be imagining things. It disappeared as soon as I tried to look at it…
Can anyone that can see these things answer me a few questions:
-
How big is the teapot (sailboat, schooner, whatever) as compared to the background?
-
What colour is it? That’s what’s always puzzled me with these coloured stereograms - what colour does the 3D image appear?
(By the way, I think these are technically called autostereograms, not just stereograms.)
r_k, the colour is always the same as the background, in that particular picture the tea pot is right in the centr of the picture and is relatively small taking up only a third of the length of the picture.
I think seeing them on computer screens is more difficult than seeing them on paper.
r_k, you might find it easier to find the background first. The background is divided in two planes divided by a horizontal line which I have marked in the annotated picture http://sailor.teemingmillions.com/images/teapotsirds_winfree_big1d.gif . Look in the original picture in that area and see if you can make out the background. Then move very slowly around. if you move too fast the whole thing falls apart and you have to start over again/
Now that I have a closer look at it, the horizontal dividing line is quite visible in the original. Go down the left edge about 56% down and you will see a straight horizontal line. Move right about 1/3 into the picture and try to make out the image there. Once you see the background try the rest
r_k, to try to help even more, I’ve traced (very badly) where (one half of the stereo images of) the teapot should appear on the picture, floating above the horizon that sailor indicated.
Though I don’t recommend using this as anything other than reference - sailor’s diagram is way more useful.
These things are cool. Want to really exercise your eyes? Find the image, and then tilt your head slightly to one side. (or tilt the picture)
Since they only work on the parallel plane to your eyes, as soon as you tilt the plane the image fades out. If you turn the picture completely upside down, you can see it again.
Wow… thanks largely to sailor’s efforts, I’ve finally managed to see one of these! They’re cool, aren’t they. Only about 10 years behind the fad, but hey, I made it at last.
It’s still a little fuzzy, maybe because my eyes are not equally matched, but it’s definitely there
Wrong. Most humans (and forward eye-facing animals) judge distances by a complex system in the brain in which it judges the angle at which your eyes are converging on said object, and therefore can work out distance through triangulation.
Parallax is a system used by animals with their eyes on the side of their head (mostly birds and prey animals), because they obviously can’t get both eyes to converge on one thing. Parallax is, as defined by the dictionary, “an apparent change in the direction of an object, caused by a change in observational position that provides a new line of sight”. This is possible, as you can see from the definition, with only one eye.
Try judging how far away something is while you’re closing one eye. Hard isn’t it? Not for me… unless I can’t move my head.
It is only recently that I have finally been able to view these doggone 3-D pictures! It sure feels like I’m going cross-eyed! But, perhaps, as has been said…once the eyes lock in on the image they uncross.
I just wonder how come, once I see the image and look away, I still don’t readily see the 3-D image? It must be different than viewing a drawing of an optical illusion and how it tricks the mind…which I can readily flip-flop between the two images.
So, why do these 3-D drawings work, and how do they create them to work out right? Bug-eyed… - Jinx 
I have found it difficult to view the “cross-eyed” images, but really easy to view the “unfocused” images. If I have dificulties at all with the unfocused type, it is usually because I’m focusing too far into the distance. For example, that was causing me some difficulty with the circle-in-a-box example drawn on-screen on the first page.
Yet, in spite of how easy I can see most of these images, it never fails to give me a slight adrenaline rush when it comes into focus. Plus, I find it to be just as intellectually “cool” as it is emotionally “cool”.
Sorry but I am pretty sure you are the one who has the wrong definition of “parallax” and most people would agree that "the brain in which it judges the angle at which your eyes are converging on said object, and therefore can work out distance through triangulation"is the definition of parallax and not “Parallax is a system used by animals with their eyes on the side of their head (mostly birds and prey animals), because they obviously can’t get both eyes to converge on one thing”.
One object, two points of view. Especially used is astronomy.
You and I agree on how it works but you got the word wrong.
Am I the only one who was seeing these things before they were invented?
Allow me to explain. As a kid, I thought it was “really cool” that I could make myself see double (by uncrossing my eyes: I find it nearly impossible to cross my eyes, without focusing on the tip of my nose). I very quickly noticed that with repeating patterns, I could make the images re-match again. This further lead to fun tricks like putting a chain-link fence at the edge of the world: The pattern matches up again, and the fence looks like it’s an infinite distance away, or further.
As soon as I realized that SIRDS are the same thing, I’ve been able to see them easily.
I did that too, Chronos. What’s funny is that now I sometimes do it without noticing that I have done it, and I’m disoriented for a second or two.
I also used the diverging method to view the occasional old stereo slide that was printed in a magazine.
When I was a kid Chronos, my parents had a car that had alight color interior fake leather “ceiling” with a bunch of regularly spaced dark holes about the size of a paper hole punch. Lying on my back in the back seat (before seat belts) staring at the ceiling on a long trip, I suddenly saw the holes sort of floating in mid-air. At the time I didn’t really understand the phenomenon of course, but it sure was cool.