HDTVs have become something of a common sight,all you need to do is pop into a large electronic mall and you''re sure to see some of these beauties on display larger panel are gaining popularity thanks to falling prices, as manufactures adopt better technologies and reap the benifits of larger scale production.The prices of larger panels have fallen to ridiculous levels.For example,some 42-inch HDTVs are now costing less then their 32-inch siblings did some time ago.

1. Evolution of the Senses
HDTVs have become something of a common sight,all you need to do is pop into a large
electronic mall and you''re sure to see some of these beauties on display larger panel are
gaining popularity thanks to falling prices, as manufactures adopt better technologies and reap
the benifits of larger scale production.The prices of larger panels have fallen to ridiculous
levels.For example,some 42-inch HDTVs are now costing less then their 32-inch siblings did
some time ago.
The larger a screen gets,the more immersive your experience gets,and this is why people still
flocks to cinema theatres to watch movies – the super huge display.However,with 47 and 52-
inch display becoming available for well under a lakh,the place for cinema like immersion
may well be your living room. Add a third dimension to the mix , and things can only get
better. Imagine watching compatible movies on a 3D screen-the action will seem to jump out at
you.At the momnet,3D display are a very new,and remember that while it's infinitely cool to
own one at the moment,there will also be invetiable hiccups associated with any new
technology. Many manufacturers have already jumped on to the 3D bandwagon,and this
includes big players like Panasonic,Sony,LG,Samsung and Mitsubishi.Also 3D is not a
technology that will be exclusive to LCD panels.Plasmas and even the newer LED backlit
displays will also get 3D love.Initilly we should see displays starting from 40-inch in size, and
this should go all the way up to the larger 70-inch plasma panels.
How Does it Works ?
All 3D displays work on the principle of Steroscopy.Remember that this is essentially a 3D
image on a 2D diaplay.This means to say that objects in a 3D scene(that is being viewed) will
not change with respect to a viewer's perspective.In other words this is not like a 3D hologram,
(expect for intenstional holographic dispalys),where a person with a difference perspective
would see something differnet -this technology is still several years away from commercial
use.Steroscopy can very simply be defined as creating the illusion of 3D in a 2D image.The
Principle is called Stereopsis.It was first explained by the english scientist,Sir Charles
Wheatstone as,”the mind perceives an object of three-dimension by means of the two
dissimilar pictures projected by it on the two retina”.This is possible by tricking your mind and
your and your eyes,by showing each eye a marginally different image,thereby perceiving
depth.This was illustrated by creating an illusion of a 3D image from 2D images that differed
slightly in their point of view.The Difference in the point-of-view is called horizontal disparity.
There are differnet technologies used to achive a 3D effect.Brodly speaking these can be
divided into two categories.The first category consists of those technologies where some sort of
3D glasses,are required to worn.The other category consists of a developing technology that
does without these galsses,and such displays are called auto-steroscopic displays.

2. 3D Displays with glasses - windows to the 3D world
3D glasses are of two types based on the type of lens used -active and passive lens ,passive lens
are obviously cheaper ,an example of a passive lens would be the simple glasses made of
cardboard and feature two of different colours- one for each eye such glasses with lens of
difernet colours are called anaglyph lens,the term owing its origins to the greek term anaglyphs
that refers to an object that protudes only slightly from a background.
Type of Glasses used for 3D views:
1)Anaglyp(Passive) Glasses.
They are cheap and only consists of one Red and one Blue lens.Here the image to be viewed
consists of two sets one with bulish ting and other with redish ting thus when seen through
theses glasses each lens blocks out its colour tricking the eyes behind blue lens to see red and
vice versa.Thus forcing our eyes to percive the image at a point different from focal point
giving an illusion of depth.
2)Polarised(Passive) Glasses.
They create an illusion of 3D by using two images that are superimposed on one screen
using different polarising filters.These glasses polarised filters are designed to filter light at
certain angles,allowing only a certain pattern of light visible to the eye.This technique is used
in theaters.
3)Active Glasses.
These are actually an acitve electronic component in a display setup.Here each lens is
actually a LCD screen,and this LCD display turn on and off at very high speed.They are
connected to compitable 3D ready displays using syncing cables or using infrared technology.
But there working principle is simmilar to the passive glasses.Each screen displays a slightly
of-set image.But what seperates it from passive glasses is that the images are not shown at the
same time.When right eye is seeing an image the left eyes vision is blacked out this all happens
to fast so as to fool our brain.
This technology demands TV with higher refresh rate than normal 60Hertz.They need 120-
200Hertz refersh rate.
New Technolgies on the Edge: Auto-Stereoscopic Displays-the way it's meant to be
There are two main technologies for auto-steroscopic displays:
A) Parallax Barrier.
Here a thin layer of material with a series of slits cut into it are coated on the
screen.These slits are cut with great precision allowing each eye to see a different set of
pixels,there by creating a sense of depth.But the proble is user positioning is limited.It is
required to have a well defined spot to else the 3D effect is lost.

3. B) Lenticular Lens.
There are tiny lenses fused to the rear side of a special film that is kept over the
screen.Two sets of the same image are then displayed,then these lenses direct the light to eyes
in such a way that they see only one image.The lenses are cylindderical in shape thus directing
the light from alternate segments to a same spot (one for right eye and one for left eye).Your
brain then interprets this as an 3D image just like in real world.
With the above mentioned technology there are a lot of glitches associated.The cost of these
3D- technology is very high.Displays require higher resolution of upto 2160p or above.the
viewers have to be in a defined viewing spot for maximum 3D effect (sweet view sopt)and the
mother of all bandwidth requirements is estamited to be upto 200GB/Sec.
The Future:Holographic Displays
The concept has been around for a while.Anyone who has asssociated with the Star-Wars series
of movies and games will be familiar with the concept.Holography,in the realm of 3D
displays,is based on the concept of “motion parallax” where the percetive of the viewer can be
be variable and the image changes and moves continuously in keeping with the viewers'
percetive.It is possible to view the object on screen from differnet directions,and each time new
facets are visible,while some disappear-similarly to what happens in real life, when you walk
around a sloid body.The picture is not restricted to the screen itself-objects can appear to be
both behind and in front of the screen.This is completely natural,and there is on motion
tracking technology applied,like in lenticular lenses.
Such Displays are made up of pixles,but these are referred to as voxles-or simply volumetric
pixles,since instead of being represented by two co-ordinates on screen they are reffered to by
three coordinates i.e., a grid in 3 dimensional sapce.The concept of a voxel originated with
holographic 3D display.A voxel is,however,a lot more relative than a pixel,because it's location
is a relative to the other voxel in a scene,since we're talking about a complex volumetric image
that differ in composition as viewing orientation changes.
Holographic displays exist,but they are very application specific.The most obvious uses are
medical and engineering applications,certain research also benifits from being able to view
objects in 3D space when it comes to home entertainment holography is still a reasonable
distace away -after all movies would nedd to be shot so as to have multiple orientation points –
bandwidth requirements would be astronomical,as would be the cost.Holographic image also
persist for a while,making them unsutiable for any sort of rapid moving scene – definetly not
what you're looking for,for any sort of video watching.The technology ecosystem for such
diapalys is also not proven,at least outside of a research lab-multimedia is a living,breating
medium and holographic dispalys are still too raw a technology to seem feasible.There have
been breakthroughs in recent years – enough to lighten up prediction gurus' eyes to the point
where they believe we could see a 3D holographic diaplay become feasible in the next twenty
years. Just wait and watch.