HDTV Aspect Ratio
Aspect ratio is the fractional relation of the width of a video image compared to its height. The HDTV format is the current standard of quality television. 16:9 is the native aspect ratio of most HDTV programming. It is 78 percent wider and taller than 4:3 ratios. When 16:9 ratio was proposed by high definition electronic production, nobody in that working group was ready to create 16:9 videos. The popular choices in 1980 were 4:3 standard TV ratio. 1.66:1 is the European flat ratio, 1.85:1 is the American flat ratio, 2.20:1 is the ratio of 70 mm films and 2.35:1 is the CinemaScope ratio for anamorphic widescreen films. It is then cut out as rectangles with equal areas and shaped them to match each of the popular aspect ratios. The geometric mean of the extreme aspect ratios 4:3 (1.33:1) which is co incidentally nearer to 16:9 (1.78:1).
16:9 was initially selected as a compromise format. The subsequent popularity of HDTV broadcast has solidified 16:9 as perhaps the most important video aspect ratio for the future. Most 4:3 and 2.39:1 video is now recorded using a “shoot and protect” technique that keeps the main action within a 16:9 (1.78:1) inner rectangle to facilitate HD broadcast.. Conversely, it is quite common to use a technique known as center cutting to approach the challenge of presenting material shot to both HD and legacy 4:3 audience simultaneously without having to compromise image size for either audience. Content creators frame critical content or graphics to fit within the 1.33 raster space. Audiences generally do not see such centrally framed information as distracting.
However, audiences of 16:9 ratio scenes can find odd moving elements that are centrally framed. 4:3 content was converted to a 16:9 standard is generally referred to as pillar boxed and many high definition television networks have adopted decoratively branded logos to fill the null area.
HDTV s has a few ways of displaying differing aspect ratios. Each mode will either stretch, zoom or crop the image variously and each mode can be used with dissimilar results. high definition signal are send in 16:9 aspect ratios. 16:9 is also known as widescreen or letter box like the screen in cinema halls. You can buy high definition televisions with either a standard 4:3 or widescreen aspect ratio. But, it is a matter of preference, whether you like the square or rectangular screen. Most programming can be formatted to fit whatever aspect ratio you prefer.
Almost every HDTV has aspect ratio control, but most sets available today limit the number of choices you have, depending upon the incoming resolutions. In most cases, you’ll have full aspect-ratio control with 480i and 480p sources generally standard TV and progressive-scan DVD, respectively but often you get fewer options or none at all for HDTV resolutions 720p, 1080i, or 1080p. Some HDTV’s especially older models restrict the number of available aspect-ratio choices with 480p sources as well.
