To create 3D images. You will need two images of the same thing, taken from the same spot and time, but one using your left eye and the other with your right eye.
Photoshop: open both images move the right eye images over the left image.
Select the top layer (right eye image), now go to image (at the top of the screen) // adjustments//levels. Now go to channels and change RGB to Red, after that change the output levels from 255 to 0 and press ok.(top layer changes to blue)
Now select the background/ bottom layer (left eye image), go back to levels, change the channel to green and change the output to 0 again (layer changes to purple, see on side bar on the right), now change the channel to blue and the output to 0 (changes layer to red).
Now reselect the top layer and change the setting normal to screen (locate on the right hand side next to the small diagram of the layers).
Put on your 3D glasses and see the 3D image you have just created. Note: you may need to move the top layer to make the image 3D, this is if the two images are to out from each other.
There is another way of doing this. Do the same this, but instead of two images, made from using different eyes. Just use one image, but duplicate it to create another layer. Background copy will be top layer. and to make it 3D move the top layer down and aross to the right abit.

this is a 3D image made using the same image