Stereo photography creates a single three-dimensional image using two ordinary 2D images. Although there’s several ways to achieve this effect, most require 3D glasses and/or a special display device. This article focuses on a technique which requires nothing more than an ordinary digital camera and photo editing software. It works by combining two separate photos into a single animated image (often using the standard GIF format), as shown below. While this clearly isn’t recommended for all your photos, it’s certainly a fun trick to experiment with when you want to create a different look.
Overview: 3D Vision & Dual Cameras
Our eyes perceive depth (in part) because they see objects from slightly different perspectives. When viewed through either eye, foreground objects change position much more than objects in the background. Hold your finger out in front of you, focus on the background, and notice how this finger shifts from side to side when viewed through either eye (called “parallax”). Now, move this finger closer and notice how it appears to shift even more than before.
A standard stereo photograph simply mimics our eyes: it’s comprised of two photographs which were taken at different positions. The greater the separation, the greater the 3D effect — and the greater foreground objects appear to shift relative to the background.
However, a camera lens’s angle of view is often different from our own eyes, so the separation distance may have to change accordingly. Other than that though, with most 3D techniques the real difference is in how the images are combined. However, this article discusses the one exception: animated “wobble” images.
How Animated 3D “Wobble” Images Work
Instead of trying to mimic what each eye sees with a separate photograph, a wobble image works by mimicking what both eyes see when you focus on an object and move your head from side to side. Our brain then interprets how objects move relative to one another — and automatically translates this into a sense of depth.
The key difference with wobble images is that both the foreground and background move substantially, while the middle/subject often remains stationary. In the example above, note how the central and right-most wooden posts remain in roughly the same position. This causes the image to appear as if it is rotating slightly when it wobbles.
Source: Cambridge in colour