Full HDTV Facts and Information
Article by John Smithson
Full HDTV (full high definition television) has become a topic of interest to more people since the final crossover to DTV (digital television) on June 12, 2009. What has changed, at least in theory, is that everyone now has access to HDTV signals. However, if one wishes to view the signal in HD it will require an HDTV display regardless of signal source (antenna, cable, or satellite).
The main advantage and interest in regards to HDTV is the high resolution. If you chose to go with an HD converter box, your television still has an analogue picture on a CRT screen. The resolution of an NTSC-analogue television is called 480i; the “i” meaning “interlaced”. This means that since there are only 240 horizontal lines available in the CRT tube and the TV camera has 480 lines, every other line is scanned at the same time for 1/60th of a second. Then the other lines are scanned. So, to portray a more vertical resolution, the TV signal is interlaced. With an aspect ratio of 4:3, the analogue TV resolution is 640 x 480i.
HDTV and full HDTV are different from analogue TV due to the resolution of each. The standard HDTV has a resolution of 720i or 720p while a full HDTV has a resolution of 1080i or 1080p. The “p” instead of the “i” stands for progressive scanning. This means that the vertical scans are done simultaneously. Using a 16:9 aspect ratio, the standard HDTV is has 1520 x 720 pixels and the full HDTV has 1920 x 1080 pixels.
The full HDTC is the product that is most favourable, but on TVS with a smaller screen than 42 inches, the difference in the resolution between the standard and full HDTVs isn’t noticeable. Therefore, any TV that has a smaller screen than 42 inches is only available in standard HDTV. So, if you want to have full JDTV, you will need to purchase a TV that is 42 inches or larger.
Three choices of screen technologies are available for full HDTV. These are rear projection HDTV, full HD plasma TV and full HD LCD TV. Rear projection HDTVs are still available but this technology appears on the decline with many manufactures dropping out of the market. Therefore, one is left with full HD plasma TV and full HD LCD TV to choose between. Since a resolution of 1080p is assumed, other factors affecting image quality to consider are response time and refresh rate, contrast ratio and color reproduction.
Features of a full HDTV plasma screen include a wide range in color, great brightness, and very large screens. The display screens can be made up to 58 inches. Also, since the display panel is only 2.5 inches thick, the TVs are only around 4 to 6 inches thick. Claims of contrast ratios in plasma televisions are as high as 50K and even 100K, but the highest contrast available is 30K. The response time is a very quick.001 milliseconds and the refresh frequencies are 600 Hz. Reasons to choose a plasma screen over an LCD display would be better color reproduction, a wider viewing angle, and fast response time. Response time can make a difference with fast moving images in such cases as watching sports and action.
One disadvantage is the power requirements in a plasma TV. The requirements can be as high as 500 watts. In addition, plasma TVs are traditionally heavier than LCD displays. However, the plasma can be mounted on a wall and the LCD display can’t.
Full HDTV LCDs have the same resolution, 1080p, as plasma HDTV. Initially, slow response times in LCD sets could result in ghosting on fast-moving images. However, refresh rates have decreased to about 2 ms with a 240Hz refresh rate. The contrast ratios have also been improved to 30K. Full HDTV LCD’s are less expensive for the high-end systems necessary for full HDTV.
A note of caution, except for resolution, when comparing specifications many reviewers question their accuracy and their meaningfulness to your viewing experience. My advice is judge for your self. In conclusion, barring financial and/or physical restraints or simple preference for smaller TV size, full HDTV is the obvious choice. If striving for a home theatre experience, make sure your full HDTV is compatible with the entire system you are planning.
