In shopping centers and appliance stores, among the various models of televisions there are 3DTVs, which are now also available at low prices and less than 500 Euros. Who is thinking of buying one, can read in detail what TV3D means and what different types exist.
To make a three-dimensional video, it is taken with a special double-shot technique, which simulates the double vision of the right eye and left eye.
The 3D cinema technique, based on a double shot, projects the two images on the screen either simultaneously or alternately.
3D televisions differ from each other based on the types of screen and glasses to view three-dimensional images.
1) Active Shutter or alternate image .
A 3D TV of this type displays frames in sequence, one for the left lens and one for the right eye, in rapid succession.
The glasses are synchronized at the same frequency as the TV so, while the frame passes through the left eye, the right one remains obscured and the images are projected alternately.
This succession occurs so quickly, about 60 times per second, that it is barely noticeable.
I say "almost" because some people notice a slight blink and often complain of sore text after prolonged use.
It can be said that this type of 3D TV is an " active shutter ", because the glasses have LCD screens and require battery power or charging via USB cable.
Glasses for watching 3D movies weigh more and cost more than other types of glasses.
These types of screens, however, are the best that can be found (and the most common) because each frame is completely blocked by the other eye, bringing less overlap between the images.
Greater brightness is also achieved because a frame is displayed only once at the same time, while passive screens show both left and right images.
2) Passive 3D (polarized)
A passive 3D screen displays the two shots together, but each frame is managed through a different polarizing filter that "aligns" the light waves in one direction.
When these light waves hit the 3D glasses, they encounter another set of polarizing filters, so that the light that is destined for the right eye goes to the right while that for the left eye to the left.
The quality of passive 3D is not so good because it does not allow to give depth and suffers from cloudy images.
As the half of the total brightness given by the TV stops, the image gets darker than what happens with the display active.
On the other hand, passive 3D televisions are much cheaper while glasses don't need batteries, they are light and cost nothing, ideal for children.
3) Lenticular (Without glasses) is the technology behind the new generation of TV3Ds that do not need glasses and can function as screens for any video source, including video games.
The technology refers a bit to the hologram optical illusions, where while looking at an image in a certain way you see it in three dimensions.
The light is directed at specific angles such that, if you close one eye and go around the TV, you should see the right and left image.
To see in 3D with this type of screen, it is necessary to stand in front of it almost perfectly, at the right distance.
Although the idea of being able to watch 3D TV without glasses is nice, the fact that there are specific viewing angles makes this technology difficult to be fully enjoyed and not practicable in cinemas.
I don't think such TVs are for sale.
4) 3D emulation and 2D to 3D conversion
Most 3D-TVs offer the additional possibility of converting normal videos and films shot in 2D to 3D.
Using a series of algorithms, the TV tries to analyze the image and distinguish the foreground objects from the background and then create the illusion of 3D images with the foreground objects pushed forward, creating a sense of "closeness".
The result is bad because the computer is not able to obtain optimal results and the image loses quality.
It is therefore worth activating 3D viewing only if a 3D movie like Avatar or others is actually broadcast.
In general, I don't know if it's worth a 3D TV or not.
The technology is good, but the limitations come from the scarcity of content, films, video games and TV channels that are transmitted in three-dimensional mode.
If you own a 3D TV, a subscription to Sky or the purchase of Blu-Ray DVDs with 3D movies to watch in the player (also to be purchased) is almost a must.
In essence, the expense can be large and perhaps not accessible to everyone, especially these days.
In another article: Differences between LCD, LED and Plasma TV to understand which TV to buy
