Full HDTV Information
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.
Full HDTV, 1080p, would seem the product of choice; however, for a TV smaller than 42 inches the difference between standard and full HDTV cannot be seen. Consequently, these smaller TV’s are available only in standard HDTV, either 720i or 720p. To enjoy full HDTV a 42 inch or larger screen is necessary.
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.
Full HDTV plasma displays are bright, have a wide color range, and can be produced in fairly large sizes, up to 58 inches is commercially available. Because the display panel is only about 6 cm (2.5 inches) thick, the overall thickness is about 4 to 6 inches. Contrast ratios are as high as 50K to 100K are claimed but, in reality, the highest available in stores is 30K with response times at 0.001 milliseconds and refresh frequencies of 600 Hz. Fast response times make plasma TV’s ideal for fast motion video (films or sports viewing). Plasma screens also are said to have better color reproduction than LCDs and to have a wider viewing angle.
However, the power requirements for a plasma TV can be as high as 500 watts. Also, plasma televisions are heavier than LCDs; however, plasma screens can be mounted on the wall.
Full HDTV LCDs have the same resolution as plasma HDTV screens. The effect of a slower response time in LCD TVs could possibly be ghosting on fast moving images. However the refresh rates have decreased to around 2 milliseconds with 240 Hz. The contrast ratios have also been enhanced to 30K. The biggest advantage of the HDTV LCD televisions is price since they are less expensive than plasmas.
With the exception of resolution, the other features, advantages and disadvantages of each of these types of TVs depends on what’s most important to you. In closing, if you have the extra money to spend, full HDTV is the optimum choice in TVs. When endeavouring in an entire home theatre, you should be sure that your full HDTV is compatible with the rest of the system.
