24-01-2011, 04:09 PM
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Authors: 1) Gaurish Mhatre 2) Akshada Burambadkar 3) Gaurav Kadam 4) Aniket Avhad
Vivekananda Education Society`s Polytechnic
Abstract
Three-dimensional TV is the one of greatest revolution in the history of television. It is the excitement among the people to know about how 3D TV works and requirements of it. This paper presents about the technologies of 3D and the implementations of it in 3D TV. Also some of details and prices of 3D TV are given
1. Content
1.1 Introduction
Many manufacturers are starting to make or at least announce televisions that will bring your viewing experience into the 3rd dimension. Some of you may remember going down to the local 7-11 to pick up those paper glasses with the red and blue cellophane lenses to watch The Creature from the Black Lagoon in 3D on your old CRT set. The idea behind those paper 3D glasses is actually much older (the first 3D film was actually made in 1922) but the basic concept continues today.3D TV works because we have 2 eyes and space between them. Our eyes see objects at a slightly different angle and our brain uses this information to reliably calculate distance or depth, especially with objects within 20 feet. 3D media uses this natural depth perception by sending a different image to each eye, our brains do the rest.
For example, if you look at a key on your keyboard with only your left eye open, and then your right eye, you will see pretty much the same image, except that each eye gives you a slightly shifted perspective of the same object. This is referred to as parallax and is crucial in our ability to perceive depth. The human brain is wired such that when it simultaneously receives images from the left and right eye each possessing a slightly shifted perspective, it is able to combine these images such that we are able to perceive the depth or distance of an object.
To take this a step further, try moving a small object close to your face and look at it with only one open eye at a time. You will notice that there is a larger shift in the position of the object for your left and right eye image when it is closer to you. If on the other hand, you place the object a few feet away from you and try the same experiment, you’ll notice that there is a very tiny shift in the position of the object in your left and right eye image. This gives you a hint at how our brain perceives depth from these visual cues.
Now that we understand why we perceive in 3D, it follows that for any display technology to be able to trick your eyes into believing that you are viewing a 3D image, it will need to provide a slightly different image for viewing to each eye via some technological trickery. Read on to learn about the different technologies being used in 3D tvs today and in the near future.
1.2 Technologies in 3D
1.2.1 Anaglyphic Glasses
Projected 3D images work on a principle of sending a slightly different image to each of your eyes. With the old red and blue glasses the different images were projected in red and blue and the glasses filtered out one or the other to create the 3D effect. The 3D effect is fairly crude and the picture has to be monochrome since the entire effect is created by filtering colors.
2.2.2 Polarized Method
Another method of producing a 3D image is using polarized lenses in the 3D glasses. Two different polarized images are shown and each lens blocks out one of the images providing a full color 3D effect that is superior to the red and blue glasses. This is the method used in IMAX and other theaters showing 3D movies. Polarization works by using filters that only let waves of light through that are not aligned with filter. Each projected image is aligned with one of the lenses and the opposite lens lets that image through. This allows 3D display of a full color picture. The polarized 3D glasses look like any average pair of sunglasses you'd find on a store rack.
1.2.3 Active 3D
A third method of creating a 3D image involves using shutter glasses. This method, often called "frame sequential display", has the user wearing powered glasses with an LCD screen that opens and closes like a camera lens. The 2 different images are shown in an alternating fashion while the glasses are synced via outboard hardware to open and close each lens separately providing one image to each eye. This effectively halves the frame rate of media being shown so a 60Hz LCD TV being used with shutter glasses will appear at 30Hz and 120Hz at 60Hz. With fast moving images this 3D technology can suffering from flickering, also the tint of the glasses effectively lowers the screen brightness by up to 50%.
1.3.1. Dual Camera: The picture information is captured using camera having two lenses. One lense is for capturing image for right eye and second one for left eye. This images are captured at alternate rate i.e switched alternately at rate of 120 Hz for smooth picture (avoid flickering).
1.3.2 3D processosr :This combines the images captured for left and right eye.
1.3.3. Encoder: For modulation of the signals to be transmitted
1.3.4. Broadcast : Signals are broadcasted using antennas
1.3.5. Antennas receive this signals and processed in the TV for viewing
1.4 More about 3D TV
Everything you watch on your regular TV you can also watch on a 3D TV. This might come as a pleasant surprise if you thought you could only watch the limited amount of 3D material that's been released so far. When you watch regular 2D video on a 3D TV, you won't have to wear 3D glasses and you won't see 3D effects. But you will see a superb picture because 3D screens are more technologically advanced, and produce the best-looking 2D pictures currently available.
More and more 3D Blu-ray movies will come out this year. We're also expecting to see 3D channels from networks like ESPN and Discovery. Ask your cable or satellite provider for details.
Also, most 3D TVs can upconvert 2D video to 3D. Of course, this won't look as good as true 3D — that is, movies and TV shows originally shot in 3D — but it will let you enjoy your TV's 3D capabilities more often
All 3D TVs will display current 2D content with no problem and no glasses required, and we don't expect their picture quality in 2D to be any worse than on an equivalent 2D HDTV. The Blu-ray 3D specification calls for all such discs to also include a 2D version of the movie, allowing current 2D players to play them with no problem.
1.5 "3D-ready" and a "3D-capable" TV
A 3D-ready TV includes the necessary infrared (IR) emitter that sends control signals to compatible 3D glasses. The emitter is actually built into the TV bezel, so you can't see it. A 3D-capable TV doesn't have the emitter built-in — if you want to watch 3D video on these TVs, you'll need to buy an emitter box separately.
1.6 Need of Glasses
It is all because of how 3D TV works. A 3D TV alternates between "left eye" and "right eye" versions of an image very, very quickly. The glasses receive a signal from your 3D TV, ensuring that the correct eye sees the correct image at all times. If you don't have the special "active shutter" 3D glasses, the image will look blurry.
1.7 Stereo Blindness
Between 5 percent and 10 percent of Americans suffer from stereo blindness, according to the College of Optometrists in Vision Development. They often have good depth perception--which relies on more than just stereopsis--but cannot perceive the depth dimension of 3D video presentations. Some stereo-blind viewers can watch 3D material with no problem as long as they wear glasses; it simply appears as 2D to them. Others may experience headaches, eye fatigue or other problems
1.8 Power Consumption of 3D TV
Panasonic’s TC-P50VT25 50-inch plasma used 160.91 watts in 2D mode and 260.53 watts in 3D mode, an increase of 38.24%.
Panasonic’s TC-P65VT25 65-inch plasma used 176.84 watts in 2D mode and 354.71 watts in 3D mode, an increase of 50.15%.
Samsung’s UN55C8000 55-inch LED used 118.73 watts in 2D mode and 152.89 watts in 3D mode, an increase of 22.34%.
The abnormal one was Sony’s XBR-HX909 LED TV, which used less power than any of the other TVs in any mode, only clocked in at 106.66 watts in 2D mode and 104.65 watts in 3D mode, a decrease of 1.92%.
1.9 Future 3D TV Technology
Autostereoscopy is any method of displaying stereoscopic images without the use of special headgear or glasses on the part of the viewer. It includes two broad classes of displays: those that use head-tracking to ensure that each of the viewer's two eyes sees a different image on the screen, and those that display multiple views so that the display does not need to know where the viewers' eyes are
Glasses are widely considered to be the weak page link in the 3D chain. Consumers would much rather be able to view 3D without having to don any accessories. This is especially true of people who already wear corrective lenses and have to wear glasses over their glasses to view 3D TV.
This provides a 3D effect without the use of glasses but is currently only used on small monitors due to the strictly defined view distance limitations involved. If the viewer moves out of the sweet spot the 3D effect will fall apart or even invert. These screens and the media that utilizes them are still very rare. Larger versions of this technology are probably on the way but it suffers from two issues, price and the very limited view angle and distance.
2. Conclusion:
Thus we have seen various technologies used for 3D imaging and viewing.
We also explained technology of 3D TV and discussed various aspects and features of 3D TV.
The cost factor and the power consumption factors will help you to buy what 3D TV you should go for if you are buying a new one.
3. Reference:
Websites:
1)http://en.wikipediawiki/3D_television
2) http://review3dtvhow-does-3d- TV-work/
3) http://3-d-tv.info/
Books:
3d Television (3dtv) Technology, Systems, and Deployment: Daniel Minoli
