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Author: Subject: [COPY] A People's Guide to High Definition
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icon1.gif posted on 2-4-07 at 01:00 PM   «:|:»  Link to post Reply With Quote
A People's Guide to High Definition



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 value of 1080 then the horizontal pixel value is 1920, the grand total of 2.07 million visible pixels is 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.

Standard HD Resoltions

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 include DLP, LCD, CRT, Plasma, and 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 offers the 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 and LCD 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 a Plasma screen can display. When purchasing a Plasma 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 two 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 or Plasma 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 display. It is the culmination of decades of research and development to replace one large electron gun used in conventional CRT displays 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 of a conventional CRT. 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 tiny diodes (per pixel) 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 ccd's and pixel 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 are only 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.

UTHD resoltuions

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?



Definition Appendix:

Aspect Ratio: 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.

CCD: 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.

Contrast Ratio: 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: 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.

Diode: 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: 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.

Frequency: 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: 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.

Pixel: 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.

Plasma: 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.

Refresh Rate: 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.

Resolution: 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 quality.
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[*] posted on 2-5-07 at 11:05 PM   «:|:»  Link to post Reply With Quote


Great article.....So big it is hard to digest in one sitting I am sure.

I also think I heared somewhere about there being limits to future HD technologys based on transfer limits of current ports used on TV's. So in order for some of the higher HD resolutions to be adapted a new connection and data transfer system needs to be improved. Based on my opinion I am sure HDMI will be the basis for this new technology, of course there are processing problems that can come up with HDMI, but in a massive HD tv what is another 60 bux on a beefy CPU to handle the data input.......

Great post, excited to see what others have to say :-D


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[*] posted on 2-5-07 at 11:43 PM   «:|:»  Link to post Reply With Quote


Awesome article. I know a ton more about HDTV now than I did twenty minutes ago. OLEDs have always kind of interested me; I'm kind of excited to see what sort of awesome TVs we get in the next ten years.

Regarding the theoretical resolutions they're working on in Japan - how does that play into computer graphics? I know modern graphics cards are pretty powerful, but I have my doubts that any of ATI's cards in the forseeable future could run a 7680x4320 display at any framerate at all. Do you think we'll see computers at that resolution before TVs? Certainly that would avoid the problem of having to capture video at absurd resolutions, though I can't imagine the size of the graphics card that could keep Unreal Tournament running at 50fps with that kind of detail. That'd be more like a graphics beowulf cluster. Ha ha ha. Ha. Ha ha. Ha.
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[*] posted on 2-6-07 at 08:39 AM   «:|:»  Link to post Reply With Quote


As for the computers being able to run the higher resolutions first..... Im not so sure. Its very possible but like you said they have to generate an image with that many viewable pixels per frame which is just insane. NHK has like 17 minutes of Ultra HD quality footage for using on their displays and I think I remember that the file for the footage is over a terrabyte or some shit like that. I will check on that.

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[*] posted on 4-10-07 at 03:40 PM   «:|:»  Link to post Reply With Quote


Found this article today:
http://www.audioholics.com/education/display-formats-technology/1080p-and-the-acuity-of-human-vision

It talks about high definition and the limits of human eyes. It is intresting but a ruff read because the human eye does not really work in pixles but rather angles which take distance from detail in effect.....It is an aspect I had never considered. What happens when displays are as high res as we can see? What about when we have maxed the FPS? Where do we go? Obviously the technology will not just stop moving....One thought that comes to mind is a digital link to the brain which could allow for us to witness images in higher quality than our eyes are capable of viewing. BRING ON THE FUTURE!


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[*] posted on 4-21-07 at 06:06 PM   «:|:»  Link to post Reply With Quote


You, my friend... have to much free time.

The more it snows,
The more it goes.
The more it goes,
On snowing
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[*] posted on 10-20-09 at 12:33 AM   «:|:»  Link to post Reply With Quote


Hi ,awesome post! Good thing ive'd drop by this thread. Nice guide for newbies like me. Hope to see more posts soon. Thanks again!

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