The merging of two images from a pair of eyes into a single spatial image, a function normally carried out by the brain, can now be simulated using digital technology. A digital camera is attached to a specialized 3D tripod head and used to capture a pair of single images of a stationary subject from carefully controlled viewpoints. Having recorded the first "left-eye" image, the camera is slid to the right by an appropriate distance to record the second "right-eye" image. It is also possible to use a traditional film camera in the same way although the pairs of images must be scanned into a computer before they can be mixed.
Image-mixing software is then used to merge the two images into a single 3D image using red and blue filters. The focus point is then set and the resulting image is viewed through red and blue 3D glasses. The red and blue filters in the lenses of the glasses effectively undo the mixing accomplished by the software to reveal a different image to each eye. The focal point adjustment controls whether the spatial image recedes or appears to pop out of the image frame. The 3D experience is surprisingly realistic.