Step 1: How 3D TV Technology Works; The principles behind 3-D HDTVs explained

By , Senior Reviewer

We all know that a television, any television, displays 2 dimensional images so how does a 3D TV create the illusion of 3 dimensions? Read on to find out.

Creating the illusion of 3 dimensions relies entirely on the fact that we have two eyes separated by a particular distance. If each eye is shown the same image shot from slightly different angles then when your brain combines the image it will appear three dimensional. This is the principle that all 3D effects use, from your old red viewmaster to Avatar shown at IMAX. The viewmaster showed a completely separate image image to each eye, 3D movies and television rely on two different methods.

In the first the two images needed to create the effect are combined into one image. Each image can be altered by a color filter or a polarized filter. With the color filter the viewer will wear 3D glasses with two different colored lenses, the glasses then block out one of the two combined images so each eye sees a different angle of the same shot producing a 3D effect. Orginially this method, called Anaglyph, required 3D to be created without a color picture but modern advances have allowed 3D to be done in color with this method although color quality still suffers. Polarization uses the same princliple but rather than altering the color of an image it alters the waves of light the viewer sees. The glasses the viewer wears have differently polarized lenses which only show one image to each eye, picture quality is better with this method and it is what is used in most 3D movie theaters.

The second method involves powered 3D glasses that have LCD screens for lenses. The glasses are synced to the display via infrared or another method and the two different angles of each frame are shown sequentially to the viewer. The lenses alternately open and shut so each eye sees a complete version of each angle rather than parts of a combined version. This actually works similarly to the old viewmaster mentioned above but rather than showing each eye a different image at the same time, the images are seen in rapid sequence. This is a very effective method of creating the 3D effect but it halves the frame rate of the content. Video normally runs at 30 frames per second (29.97 to be exact) so with this method of 3D each eye is only seeing 15 frames per second, this lessens the apparent smoothness of the content.

Another method of 3D, without glasses, has been around for a few years but it is just now starting to come to market. This method uses filters or lenses in front of the screen to direct the separate images to each eye. Early versions of this technology required the viewer to maintain a very specific distance and position in relation to screen, even relatively minor deviations would break the 3D effect. Today combining the filters and/or lenses with a camera and face recognition software creates the ability to just the screen in real time to project to the split images to the current location of the viewer's eyes. Nintendo is using the version of this technology that requires your head to remain in a fixed area on their 3DS handheld and Microsoft has even created a screen that uses face recognition that can project 3D to 4 people in real time.

Even though 3D viewing has been around for more than century in one form or another is really is still in it's infancy. Expect more 3D breakthroughs in the years to come as it's popularity is on the rise again.

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