Without further ado, here's a single image random dot stereogram (SIRDS)
for viewing. This one simply has the letters "3D" in it, floating over the
The SIRDS is a single image which cleverly contains two images merged
together, with hidden cues that the brain can use to see a 3D image
within the apparently random black and white dots that make up the image.
As entertaining as the black and white random dot stereogram images are, adding a little
color can make stereograms even more interesting. In the next example,
the random black and white dots are replaced with random colored dots.
Even more exciting, by rotating 3D objects and creating a stereogram for each
position, animated GIFs can be made to generate 3D movies, as in the following
two animated images (fan on the left, a pendulum on the right).
Finally, stereograms which use images for the background,
rather than random dots, are even more interesting to view as this
next example shows (it's a 3D skull on a background of bones).
Dual Image Random Dot Stereogram
The first stereograms used two separate images - one for each eye.
The two image random dot stereograms are easy to create and by
looking at how one is made you get a very good sense of what must
be done to an image to allow the brain to perceive 3D content.
Single image random dot stereograms carry the concept further by
merging both images into a single image. There's more information
on this technique elsewhere in this site.
To create a double image random dot stereogram, start with the
following two identical images which are simply filled
with random dots.
Then copy a small area of one of the pictures, such as the marked
square in the following example.
Then paste the copied portion of the image back onto the original
image and move it slightly in either direction:
This gives you two images which started out identical, but are now
slightly different. When placed side by side, despite the apparent
randomness of the content of both images, the brain can detect the
difference and will translate it as a 3D effect as shown in the following example:
In the next section, Concepts, the
technique for creating a single image stereogram is introduced.