Stereoscopy

Concept
Our two eyes sees objects from a slightly different angle. This around 2 inch difference in point of view helps one eye see the sides of an object better than the other eye. This difference is called parallax. We know how far an object is from us due to this parallax.

How stereoscopy works
The effect of stereoscopy is created by taking 2 images which is shot with a mild horizontal offset (only) and forcefully displaying the left image to the left eye (only) and right image to the right eye (only).


A Quick Experiment
Requirement:
1. A digital still camera
2. A system with photoshop
3. 3D anaglyph glasses (Blue Red glasses)

Procedure:
Take a photo of any thing, preferably that covers object that is far and near.
Slightly shift you camera to your right about 6inches but looking at the same places.
Strictly no up and down and no rotation. Try to be as accurate as possible. Best way is to place your camera on a table take one pic, shift it to the right slightly take another one.
First photo is your left image and second your right image.

Bring these two picture to Photoshop.
Make a psd file with both images as 2 layers.

First check the images whether it will work:
Reduce the opacity of the layer that is on top and see whether the images are matching horizontally. There will be vertical offset though.

If it is looking good reset the opacity back to 100%.


Now the challenge is to force your left eye see the image that is taken from left and the right eye see the image that is taken from right.

There are many methods, for home experiment we can only think of anaglyph glasses (spectacles with red color glass for one eye blue for the other).

What these glasses do?
Basically, the red side of the glass cannot see red channel of your image and the blue side cannot see the blue channel.

So in photoshop we have to select the left image and remove red channel.
Select the right image and keep only the red channel (remove blue and green channel). Then modify the mode of the top layer into multiply. Which will produce the anaglyph 3D image and there you go.
See this image with your 3D glasses. If image is not appearing in 3D, reverse the glasses and check.