Since the federal regulation of mandatory DTV (digital television) signal, the subject of full HDTV (full high definition television) has become a more popular topic of discussion and has become more of an interest to the public. With the digital changeover, now everyone has access to HDTV signal. However, an HDTV display is still necessary in order to view high definition no matter what type of signal you have (cable, antenna, or satellite).
For HDTV, resolution is the key word, defining how detailed an image can be displayed without blurring. Those who opted for the HD converter box are still viewing a picture on an analogue CRT screen .NTSC-analogue TV resolution is defined as 480i. The 'i' means interlaced. This results from the TV camera having 480 horizontal lines of resolution while the CRT tube has only 240 lines available. So every other line of the 480 is simultaneously scanned for 1/60th of a second then the remaining lines are scanned. Hence, the TV signal is "interlaced" giving the appearance of more vertical resolution. With an aspect ratio of 4:3 (width x height), the analogue television resolution can be described as 640 x 480i.
So how do HDTV and full HDTV differ from analogue TV? Certainly the most obvious feature is the resolution. Standard HDTV has a resolution of 720i or 720p and full HDTV has 1080i or 1080p. The 'p' signifies progressive scanning versus interlaced, i.e. all the vertical scans are done at the same time. With a 16:9 aspect ratio in HDTV this results in 1520 x 720 pixels for standard HDTV and 1920x1080 pixels for full HDTV.
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.
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.
Of course full HDTV plasma is not perfect. The power requirements can be as high as 500 watts for some large screen versions and because the screen is made of glass, glare can be a problem. Plasma displays are heavier compared to their LCD counterparts but can be wall mounted.
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.
For HDTV, resolution is the key word, defining how detailed an image can be displayed without blurring. Those who opted for the HD converter box are still viewing a picture on an analogue CRT screen .NTSC-analogue TV resolution is defined as 480i. The 'i' means interlaced. This results from the TV camera having 480 horizontal lines of resolution while the CRT tube has only 240 lines available. So every other line of the 480 is simultaneously scanned for 1/60th of a second then the remaining lines are scanned. Hence, the TV signal is "interlaced" giving the appearance of more vertical resolution. With an aspect ratio of 4:3 (width x height), the analogue television resolution can be described as 640 x 480i.
So how do HDTV and full HDTV differ from analogue TV? Certainly the most obvious feature is the resolution. Standard HDTV has a resolution of 720i or 720p and full HDTV has 1080i or 1080p. The 'p' signifies progressive scanning versus interlaced, i.e. all the vertical scans are done at the same time. With a 16:9 aspect ratio in HDTV this results in 1520 x 720 pixels for standard HDTV and 1920x1080 pixels for full HDTV.
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.
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.
Of course full HDTV plasma is not perfect. The power requirements can be as high as 500 watts for some large screen versions and because the screen is made of glass, glare can be a problem. Plasma displays are heavier compared to their LCD counterparts but can be wall mounted.
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.
About the Author:
James Junior writes interesting articles about Full HD TV televison including information about HDTV online
0 comments:
Post a Comment