Let's talk - and see on a simple example - how stereograms (3D pictures) work. It will help us to create our own 3D photos and experiment with them.
What see your eyes
When you make a 3D picture (stereogram) you use one important feature of human eyes - every eye sees a different picture. The difference depends on the distance of every object on the picture from the head of the observer. We won't do a long explanation - let's make a short experiment instead. Take anything to your hand - for example a pen.
Well, you have a pen in your hand. Point it up. Give it before your eyes to a distance to see it well. Now take a look at any object behind the pen - for example at a computer monitor or at a cup of tea on the desk. The pen should be in the distance about 6 inches from this object.
Close your left eye and shift the pen to place it in a position which you can easily remember. For example before an edge of the monitor. And now open your left eye and close the right one. Do you see the difference? If you did the experiment carefully, you could see the pen shifted to the right (but it hasn't moved really). No success? Try it again.
From our experiment we can see the left eye sees things, which are in front (for example in front of the edge of the monitor), a little bit more to the right than the right eye. And the things at the back a little bit more to the left (you can try to position the pen behind the edge of the monitor). How to use it for creating a 3D picture? If you have one photo from the point of view of the left eye and one photo for the right eye then the only thing you have to do for 3D is - to deliver every photo to it's eye. How? You can merge the photos in a special way and then to watch them through a special glasses (because without the glasses every eye sees the same).
The most affordable glasses you can use for watching stereograms (3D pictures) are glasses with red-blue (red-cyan) slides. The glasses you can get here - with our subscription packets. How the glasses work?
If you give the glasses before your eyes (red slide before the left eye, blue slide before the right one) then you can see this: left eye sees the red world and the right eye the blue world. But it isn't all. There is one more important thing. If something is red (for example a red cup on the white desk) then the left eye almost can't see it (it sees the red cup on the red desk), right eye sees it as dark. Similarly the right eye doesn't see the blue (blue-green) things. If the background isn't white then the situation changes - but the basic princip is the same - different eyes see different things.
And that's all the trick. If you take your photos for the left and right eye and use only their red or blue (bluegreen) part and then mix it then you get the stereogram (3D photo). When you use the glasses every eye sees only the part of 3D picture which has to see. But how to do this?
To do a stereogram from the left and right photos you should use an appropriate software (computer program). You can buy - and download here the software 3DJournal, which we've created to help you to make your own 3D pictures or 3D movies. There is also a limited FREE version available here. More about the software you can read in this article
We've created the program with functions which can help you to make 3D pictures from photos taken by usual cameras - and 3D movies as well.
One more thing
The 3D pictures which are visible with red-blue glasses are called Anaglyphs. There are some othe technologies to make and watch stereograms - for example with polarisation or LCD shutters. But only anaglyph is so cheap and easy to make at home.