Imagin you've just bought a new iPhone or iPad, but all the actors on your favorite shows look unnaturally bloated and fat. Or there are black bars at the top and bottom of the screen-and on the left and right. Or everything on your favorite DVDs looks tall and skinny. All of these problems are examples of one of the most important-and least understood-issues in the home-theater world: aspect ratio. We'll take you step by step through the common aspect-ratio problems-and their solutions-on both standard and wide-screen screen.
An image's Aspect Ratio, or AR, represents a comparison of its width to height. Notation for Aspect Ratio is normally in the form of X: Y, where X represents screen width and Y represents height. For example, a standard analog TV has an AR of 4:3 which means that for every 4 units of width it's 3 units high. This could be 4mm wide and 3mm high, 16in wide and 12in high or 24m wide and 18m high. The exact dimensions aren't important, so long as the ratio between them is correct. In order to make it easier to compare different ARs it's common to see the width compared to a set value of 1. Using this convention 4:3 becomes 1.33:1, which may also be referred to as 1.33, with the 1 implied. Although this is somewhat less precise, with only 2 digits of precision (decimal places), the error is very small. And it makes it easy to tell that 16:9 (1.78) is wider than 4:3 (1.33).
The 4:3 ratio (generally named as "Four-Three", "Four-by-Three", "Four-to-Three", or "Academy Ratio") for standard television has been in use since television's origins and many computer monitors use the same aspect ratio. 4:3 is the aspect ratio defined by the Academy of Motion Picture Arts and Sciences as a standard after the advent of optical sound-on-film. By having TV match this aspect ratio, films previously photographed on film could be satisfactorily viewed on TV in the early days of the medium (i.e. the 1940s and the 1950s). When cinema attendance dropped, Hollywood created widescreen aspect ratios(such as the 1.85:1 ratio mentioned earlier)in order to differentiate the film industry from TV.
16:9 (generally pronounced as "Sixteen-by-Nine"; alternates include "Sixteen-Nine" and "Sixteen-to-Nine") is the international standard format of HDTV, non-HD digital television and analog widescreen television (EDTV) PAL-plus. Japan's Hi-Vision originally started with a 5:3 ratio but converted when the international standards group introduced a wider ratio of 5⅓ to 3 (=16:9). Many digital video cameras have the capability to record in 16:9, and 16:9 is the only widescreen aspect ratio natively supported by the DVD. DVD producers can also choose to show even wider ratios such as 1.85:1 and 2.39:1 within the 16:9 DVD frame by hard matting or adding black bars within the image itself. Some films which were made in a 1.85:1 aspect ratio, such as the U.S.-Italian co-production Man of La Mancha, fit quite comfortably onto a 1.78:1 HDTV screen and have been issued anamorphic ally enhanced on DVD without the black bars.
Related reading: Convert Video Aspect Ratio from 4:3 to 16:9 for Widescreen Display
1.3 = 4:3: Some(not all) computer monitors (VGA, XGA, etc.), SDTV
1.414 = √2:1: International paper sizes (ISO 216)
1.5 = 3:2: 35 mm film
1.6 = 16:10, widely accepted computer displays
1.618: Golden ratio, close to 16:10 = 8:5: Widescreen computer monitors (WXGA, etc.)
1.6 = 5:3: Super 16 mm, a standard frame ratio among many European countries
Carolyn Young worked in the Marketing Promotion Department of Digiarty Software. Besides occasional writing, she offered brilliant market ideas.