Stereoscopic 3D (also known as True 3D), is a technique that uses two dimensional images and adds depth to them, making the images look 3D. It can be achieved by having two cameras set up very close to each other (like the distance between your eyes), filming the same action. These cameras are filming an sequence for each of your eyes and when played back along side each other, the illusion of depth is then achieved.
Stereoscopic 3D is growing rapidly, being use in major films, such as Avatar, and is even now being presented in video games. Films that use 3D have been reported to generate as much as three times as much money compared to the 2D version of the film. The technique has been around for a long time, however it hasn't been widely used due to the fact that there hasn't been high enough quality equipment as it is very expensive.
Many companies, such as Sony, have now released Stereoscopic 3D televisions and also they have released an update for the Playstation 3 that will mean Playstation games can also be played in 3D. However, the down side to these devices is that to view the content in 3D, you have to wear LCD Shutter Glasses to make the image 3D. This is because the majority of programs or games that you can watch or play won't have been recorded using two off-set cameras, so the glass will output the visuals to your eyes how they were meant to be viewed.
The glasses work by synchronising with the Stereoscopic 3D display to separate the images that appear as a conjoined mess without the glass, and only show the right images to the right eye and the left images to the left eye. The glasses have liquid crystal in them which either allow the light to pass through them for the viewer to see or block the light so the viewer cannot see it.
Television have a refresh rate that is measure in hz (hertz). If a television has 100hz, this would mean that it refresh 100 times per second. This mean that the footage for the left and right eyes will be displayed every other frame on the television, one after another. So images for the left eye may be displayed at 01, 03, 05, and the images for the right eye would be displayed at 02, 04, 06. If you were to watch the screen without the glasses, it would look like a big blurry mess. The LCD Shutter Glasses will sort out which images each eye is supposed to see, meaning the left eye would see the images at 01, 03, 05 and the right eye would see the images at 02, 04, 06.
Anaglyph 3D
Anaglyph 3D works in a very similar way to Stereoscopic 3D. As with Stereoscopic 3D, they are created by having two images that are captured from slightly different angles, normally achieved by setting two cameras next to each other and having the lenses about 3 inches apart, which is like the natural space between your eyes. The left eye will be rendered to red (blue and green channels set to zero) and the right eye will be rendered to cyan (red channel set to zero). When we look at the image through anaglyph glasses the images will be separated, as the left eye will only receive the red signals and the right eye will only receive the cyan signals.
When we look at the 3D image, our brains see the red filtered areas as white and the blue filtered areas are seen as black. The brain then blends the images together and sees the differences as being differences in distance rather than colour. The colours red and cyan are used because they are at opposite ends of the visible light spectrum, this is why the black and white areas area different.
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