The first thing to do is to provide some information which will answer the questions I have been sent.
The most popular format for 3D pictures, without using special glasses or viewers, is the one that uses the cross eyed technique. This sounds a bit odd but bear in mind that the Magic Eye 3D images that were once so popular relied on people going slightly boss-eyed; so it's not unusual for the viewer to develop a knack of doing either. There came a point where the cross eyed method became more preferable, perhaps because it was easier to learn. Way back when, books like Magic 3D by Tom Johnstone discussed how to create the images and may have been the first to use the phrase 'photographic freeviewing' to describe viewing 3D photos without special glasses. The principles involved were partially used in other books such as Boris Vallejo's 3D Magic mixed Magic Eye images with 3D renderings of Vallejo's fantasy artwork. Both books introduced the cross eyed method on some of the images as an alternative to Magic Eye boss-eyed technique.
In some ways the crossed eyed method harks back the Victorian stereoscope viewers. On these the double image of a scene used what is now known as the 'parallel' method. The image for the left eye was on the the left and the image for the right eye was on the right. The cross eyed method has the image for the right eye on the left and the image for the left eye on the right. That is about the only difference.
The images used to be created by one method; there were two cameras, not more than six centimetres apart (to approximate the view of a pair of human eyes), and each take a photograph of the same scene at the same moment. When the photographs are placed or printed side by side they can be viewed by either the parallel or cross-eyed method as 3D images.
Computer technology eventually had a say in the matter and various methods were thought of to take a single photograph and alter it, pixel by pixel if need be, to create a second photograph which, when placed next to the original, would create the required 3D effect when viewed cross eyed or through a stereoscopic viewer.
Hopefully, that is enough dull tech stuff to satisfy the curious.
The results of the software I have been testing is that only the double images created for the cross eyed method are of any worth; even then I still have to correct each image for anomalies. The other 3D images it can produce, such as anaglyph (which require the red/blue lenses on 3D viewing glasses) are abysmal.
Below is a 3D image, for the cross eyed method, of Veronica Lake. I do not know the name of the owner of the copyright of the original to give them credit. This image and the one in the previous blog entry were chosen by others as photos to test the software. Once again, the instructions are to click on the image to load a larger version; then look at the two images cross eyed until a new image appears between them - that image will appear tobe 3D.