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By : Emelia Morseton
Submitted 2011-03-11 16:22:05 The amount of 3D TVs sold has continued to rise over the last year and shows no sign of slowing down. The purpose of this article is to describe the process by which 3D pictures are filmed and how your TV displays them. A knowlede of how 3D technology works can help when buying a TV. Without this knowledge it is not easy to determine if a particular TV has a weakness. This article does not include 3D TV without glasses. The technology for 3D TV without glasses is still in its infancy and there are several limitations,[link widoczny dla zalogowanych], such as limited viewing angle and small screen sizes, which make it an inferior product at this time.
The thing to look at first is what is the difference between a traditional 2D TV picture and a 3D picture? A 3D picture has depth of field of view as the third dimension, whereas a 2D picture only has two dimensions - basically up and across your TV screen. With 2D pictures the brain forms its own impression of depth based on what it expects in real life. The brain knows for example that things that are smaller than expected are in the background and vice-versa for things in the foreground. In real life the depth information is generated by the different viewpoints of our eyes. Each eye sees objects from a slightly different angle. The brain combines the images from each eye which enables it to generate a 3D perception of actuality.
A 3D TV picture must therefore contain two images,[link widoczny dla zalogowanych], one for our right eye and the other for our left eye. This brings about two problems. How to generate two images and how to display them so that our brain sees a 3D picture? The answer to the first question is that a 3D program contains two picture signals that are filmed by a camera that has two lenses, roughly the same distance apart as our eyes. A 3D TV therefore receives the pictures in two streams of video but that still leaves the problem of how to display them. There is only one screen on the TV of course.
The solution involves a bit of trickery. The brain is fooled into thinking that it can see two separate images,[link widoczny dla zalogowanych], one for the left eye and the other for the right eye. A 3D TV displays the pictures for each eye alternately. In order for the system to work, the eyes must only see the appropriate image and not the image that the other eye should see.
At this stage the 3D glasses come in. The glasses use something known as active shutter technology, which makes use of a LCD built into each lens of the glasses. When the left picture is displayed, the LCD in the right lens turns black, in other words opaque, so that the right eye cannot see it. Then the right picture is displayed and the right LCD becomes clear while the left lens turns black. The glasses are synchronized to the TV so that the lenses open and shut at the correct times.
By alternating the pictures at high speed, the brain is therefore tricked into thinking it is looking at a 3D image on the TV.