Now in the modern digital days there are many options to creating these 3D images and several of them are very expensive stereo cameras (2 lenses) used for augmented reality and 3D mapping. We will not be discussing these here, we are going to explore shooting 3D images with a digital camera, or even with a phone and creating the red/blue effect within photoshop!
The first step to creating a 3D image is to find the proper subject matter. Nobody wants to see a 3D image of a billboard or a poster on a wall, what fun is that? You need to find something with stuff sticking out here and there to make the image interesting. Lots of foreground and background variation, but keep in mind the foreground objects will have the most 3D effect and could be distracting, so try to keep those items around the framing of your image.
Next you will need to take 2 pictures, like the old fashioned cameras did. But since you are probably using a single lens on your camera or phone (multiple lens phone cameras will not work for this), you will need to move the camera slightly to create your second exposure. Very important: since our eyes are arranged horizontally, we also need to make our camera move horizontally or this will not work. Landscape orientated photos work best. 55mm is the average distance between a human’s eyes, so we will need to move the camera 55mm or just over 2 inches. So shoot one image, move the camera then shoot another. It is helpful if you have something to set the camera on, as you want the position of the lens to move just that little bit and not all over the place to keep the 3D effect as accurate as possible. Try keeping the focal plane the same for both shots (try not to rotate the camera when moving it).
So, you got your pictures shot and now you have 2 images. If you could put them side by side, on screen, and close one eye and then switch open eyes really fast this would work great, but nobody I know can do that, so we need to put these images together into one to create the effect. So open both images in photoshop, then drag the background layer from one image on top of the other (while holding shift of course) so you will have an image with both shots in separate layers (you can close the image you dragged from we do not need it anymore). Double click on the background layer, you should now have 2 layers, Layer 0 on the bottom and Layer 1 on the top. One of these will be the left eye shot and one will be the right. If you know which one it which, you only have one more step to create a 3D image. Next step is to click on the top layer (Layer1) and double click on the layer itself and turn off the red channel: