Our modern High Definition TV has its roots in television technologies dating back over 70 years. Prior to the Marconi EMI
system of 1936 the first experimental systems had as few as 12 transmitted lines. When the marketed versions of television reached the masses they
were advertised as High Definition Pictures. By todays standards it would't even be comparable to standard over air television. Most of United
States receives a standard digital HD signal over the air in either a 1080i or 720p resolutions
. As with any new
technologies many problems had to be tackled, most recently of which has been the problem of standards among governing bodies.
The terms and technologies used to describe HDTV can be somewhat obscure and overwhelming, so I will give a brief over view of the more important
elements. 1080p, 1080i, 720p, 480p are the current resolution
standards in HD, but what do they mean? The easy way to begin is
to understand that the number that is given represents the vertical pixel
value in an assumed 16:9 ratio and the
letter at the end denotes the picture format as either interlaced or progressive. If the image has a vertical pixel
of 1080 then the horizontal pixel
value is 1920, the grand total of 2.07 million visible pixels
the result. When it comes to the image format it should be said that progressive scanning is the superior method for moving images. An image that is
sent in an interlaced format uses two fields to show one frame; for each piece of data that is sent only half of the total image is received and
capable of being displayed. The inherent flaw results in an image that is compromised by awkward lines and pixalation when compared to the same resolution
in a progressive format. One thing must be said in the defense of interlaced formating though: it saves bandwidth
without too much loss in quality.
The time line of High Definition begins with the first wide spread marketed television format. This format was developed by Alan Dower Blumlein who
was working in a group under Sir Isaac Shoenberg. This format was an analogue monochrome image called the Marconi EMI system and it was the first
implemented system with interlacing. The system used two complimentary 377 line images broad casted 50 times per second (50 Hz) creating a view able
image at 25 frames per second. The system utilized 405 lines though only 377 were used for picture, allowing for the remaining lines to be used for
sound. This system was made popular by the news given out during World War II and would see use until January 3rd, 1985 by the BBC. Though it was
the first to coin the phrase High Definition it was by no means true to the term.
The first broadcasted television format that offered more than 480 vertical lines of resolution
was called MUSE or Multiple
Sub-nyquist Sampling Encoding system. It was the culmination of research done by the Japanese company NHK, which translates to STRL or Science &
Technical Research Laboratories. It was a technical achievement of the day that allowed for 1035 lines of viewable image. It used a cool trick based
on the concept that the human eye responds less to lower frequencies. With this idea they broad casted the lower video frequencies w/ less power so
that the higher video frequencies could have more of the available broad casting power. This trick allowed for the received frequencies to be
amplified equally. The system used two fields at 60 Hz (60 times per second), the total lines broad casted were 1125, though only 1035 for picture in
a 1.66:1 frame ratio. This system went on line in 1979 as an Analog High Definition and still broadcasts today in Japan as BS-digital channel 103's
parody channel. It will cease to be broadcast sometime this year.
Our modern HDTV was first released in the United States in the late 1990's (first in 1997 but varied dates depending on regional availability).
Current HDTV broadcasts are defined by the ITU-R (International Telecommunication Union's Radio communication Sector) as either 1080 active
interlaced or progressive lines or 720 progressive lines at a 16:9 aspect ratio
. In the United States however only 1080i
or 720p formats are currently being broadcast with plans by some service providers to offer 1080p in the near future. The group responsible for a
unified HD format in the United States is the Digital HDTV Grand Alliance which is comprised of 7 large tech companies: AT&T, General Instrument, MIT,
Philips, Sarnoff, Thomson, and Zenith. To watch HDTV a person needs to have a HD television service coupled w/ a receiver/decoder box w/ an HD
capable television or an HD television that has a built in HD receiver that is connected to an antenna. Currently only 33 million house holds in the
United States have HD televisions and even fewer have an HDTV service.
Only 33 million people own an HD capable television set in the United States, a minority of the population to be certain. With each passing day
though more and more people are wanting to make the upgrade to High Definition, but what are the features and settings that one wants in a new HD
television? With the latest generation of gaming consoles and HD DVD's/ Blue Ray Discs offering resolutions
as high as 1080p,
it makes little sense to purchase a new television that doesn't support that resolution
. The main forms of television today
on the horizon is SED. Each has its own advantages and disadvantages. The technologies wont be covered each in its entirety but rather with emphasis
on preferences based on what is to be used by an average consumer living in Denver, CO. For a higher elevation DLP
most versatility in options and capacity. Living at or above a mile in altitude means that any method of display that uses a non-mechanical means
will be at the mercy of whatever reaction is used. Plasma
are at a distinct disadvantage. Plasma
televisions use different sized pixels
depending on the screen size, the larger the screen size
the longer it takes for the image to be changed. Only the most recent advances in plasma
technologies concerning ultra-small
screens have allow companies to raise the actual resolution
screen can display. When purchasing
television set always consider the potential for image burn, as Plasmas
are notorious for
having an image captured forever on their screens when left on one channel or paused movie/video game for too long. LCD's
largest shortcomings are its refresh rate
and contrast ratio
. These two specifications go
hand in hand as one is the displays ability to show absolutely no light or full light in any given pixel
compared to its
nearest neighbor pixel
and the other specification is the rate at which a display does the above process. LCD's
must wait for a pixel
crystal to respond before it can change its color, waiting on a chemical and
electrical reaction to be completed before it can be done again. With a CRT
its a matter of the photons being shot and expelled
before it can be refreshed, little to no delay. A CRT
is not a good choice as they are incredibly heavy for its visible screen
size. A DLP
is a far better choice as they generally offer the best contrast ratios
and refresh rates
. The key behind these televisions is one or three tiny chips that rely on ultra tiny movable mirrors to display its
image. They take up more space than an LCD
but less than a comparable CRT
and at a fraction of the weight. The market is always changing with new technological breakthroughs, some of which are only achieved through
improving past technologies.
SED or Surface-conduction Electron-emitter Display is a futuristic approach to the classic electron gun found in a CRT
It is the culmination of decades of research and development to replace one large electron gun used in conventional CRT
with thousands of tiny electron emitters. This technique allows for far less power consumption when compared to equivalent sized Plasma
displays while still maintaining the higher contrast, brightness, and refresh rates
. The problem wont be in the technologies unfortunately, as recent developments in the joint venture bringing it
to production has just lost its manufacturing contributer. Another technology culmination has been achieved between the led and glue manufacturers to
bring OLED or Organic Light Emitting Diode
based screens. Modern adhesives allow for ultra tiny circuits that are
strong, bendable, and thin enough to be coupled with SMD or surface mounted device. These displays have made their way into cell phones and MP3
players with large panel displays expected to hit the market in the next nine to eighteen months. The genius behind OLED displays are three ultra
) mounted on a chipset. The possibilities are endless, only the market will
dictate how well these versitile displays do.
The subtleties of HD begin with how they started, visual quality. Images can only be captured in a resolution
that is as high as
two things: equipment and reality. What is used to capture the image is obviously the changeable factor. A typical 35mm photograph or even a high resolution
digital photograph is at a displayable resolution
equal to HD! Problems occur when it comes to
capturing the image in motion. Older movies that are captured on film are capable of being displayed on modern HD televisions in HD quality. The
problems originate from the films original frame rate as compared to todays, natural degrading of the original film, and of course the people who own
the rights to the film. The next time an older movie (ten to twenty years or more) is on some network programing take the time to watch some of it.
All original films were shot in a wide screen aspect ratio
even though all distributed home cassettes only show a 4:3 aspect ratio
. Some tell tale signs are the typical “modified to fit this screen” image shown at the beginning of films,
vertically elongated characters when in fact the natural image has been compressed to fit the 4:3 screen format, and clipped body parts in a shot
that seem like they should be shown in the frame. The current trend toward higher resolution
video is entirely driven by the
consumer. Films have been shot in a resolution
which is higher than the standard equipment on which its played for years! As
the average economic standard for HD technologies increases there will be ever increasing capabilities. The Japanese company NHK has been working on
a HD resolution
of 7680x4320 pixels
, or roughly four times that of the current high of 1920x1080.
This may or may not take foot in the future as its a resolution
so high it requires four current 1080p capable televisions
running in unison. Another reason it might not take off is that no camera can actually record an image at that high of a resolution
, NHK can only achieve the resolutions
claimed by using a heavily modified arrangement of four 64mm
shifting to go from 3840x2048 to 7680x4320. This huge jump in resolution
isn't the only larger resolution
possible. There are many theoretical resolutions
that are higher than 1920X1080 and not as immense as 7680x4320, but those resolutions
theoretical and haven't been pursued by industry developers when concerning the captured and displayable image. Chi Mei Optoelectronics has
developed a screen that can display a resolution
of 2560x1440. They, like NHK, are still limited by the image resolution
that is captured and then displayed.
Television technologies have come a long way from pictures with only 12 lines to what we see today. As with any technology the future is unclear, but
it is without a doubt a genie that cannot be put back in its bottle. The human species hasn't even begun to use television to its full capacity, and
yet most of use couldn't imagine life without it. Take care when deciding to wade into High Definition's technological swimming pool as there are
many things to consider and even some sharks to avoid. The many obstacles are well worth the advantages of High Definition Television, which can be
made apparent every time you have the chance to use an HD media on an HDTV. High Definition Televisions offers vastly superior clarity, textures and
enjoyment when its utilized to its fullest potential. Why not take a look?
: The smallest expressible number of vertical height to horizontal height for a graphic display. Standard
image TV is a 4:3 aspect ratio, meaning for every 4 horizontal units there is 3 vertical units. HD formated images are usually in a 16:9 ratio,
meaning for 16 horizontal units there are 9 vertical units. The standard unit of measure is a pixel.
: Charge-coupled device or more commonly known as Color Capture Device. An array of light sensitive capacitors that
are used to capture an optical image to be displayed on a digital media.
: A graphic display uses pixels to show colors, a contrast ratio is the displays ability to show its
brightest color relative to its darkest color per pixel. The higher the contrast ratio the better the displays ability to show extreme bright colors
next to extreme dark colors.
: CRT or Cathode Ray Tube is a means of displaying an image by firing an electron gun inside a vacuum. As the
electrons pass through the tube they reach the displayable surface that is coated in phosphorus and react. The electrons cause the phosphorus surface
to change colors in the form of a picture.
: An electrical component that limits the direction of flow for an electrical current. For our purposes its
essential to the function of an LED or OLED in flashing.
: DLP or Digital Light Processing is a method displaying an image in front or rear projection televisions. The chip
technology was developed by Texas Instrument's in the late 1980's and is widely used capture or display devices. The method uses ultra tiny
mirrors for each displayable pixel in the image, when the light/color for that pixel changes the mirror repositions itself which allows one of three
primary colors or white, black, or varied shades of grey.
: referring to the number of times an event occurs in any given increment of time. Our use of the term refers
to wavelength or the number of times a wave crests' each time per second; when measured in units per second its unit is called Hertz or Hz.
: LCD or Liquid Crystal Display is a graphic display that uses suspended liquid crystal molecules that are sandwiched
between two electrodes and two polarized filters. When a current is applied to the electrodes the crystal molecules change orientation and therefore
allow more or less light to be passed through them.
: The smallest point in a graphic image. The term is a contraction of “picture element” and in our context
is referring to a point on a display device.
: When we use the term plasma we are referring to a method of graphical display. The technical term “plasma”
refers to a gas in an ionic (excited on a molecular level) state. With a graphic display the “plasma” refers to the noble gases, usually neon and
xenon, that are sandwiched between two plates of glass and excited to a plasma state by electrical current. This process is utilized to make varied
colors of the displayable image.
: Not to be confused with frame rate, refresh rate refers to number of times a display turns the light source
on and off per second to show the image. A display might show a frame rate of 30 but in those 30 frames it turns the light source on and off three
times, this means the display has a refresh rate of 90 Hz.
: There are many definitions for this term, but for our purposes we use it to refer to image clarity as a result
of the number of pixels inside a given area of a graphic display. The more pixels in a certain area the higher the resolution or picture