4:3 standard
4:3 (1.33:1) (generally read as "Four-Three", "Four-by-Three", or "Four-to-Three") for standard television has been in use since the invention of moving picture cameras and many computer monitors used to employ the same aspect ratio. 4:3 was the aspect ratio used for 35 mm films in the silent era. It is also very close to the 1.375:1 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, movies originally photographed on 35 mm 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. However since the start of the 21st century broadcasters worldwide are phasing out the 4:3 standard entirely, as technology started to favour the 16:9/16:10 aspect ratio of all modern HD TV sets, broadcast cameras and computer monitors (though recent computer displays such as the Chromebook Pixel at 3:2 are reverting to more squared ratios).
16:9 standard
Main article: 16:9
16:9 (1.77:1) (generally named as "Sixteen-Nine", "Sixteen-by-Nine" and "Sixteen-to-Nine") is the international standard format of HDTV, non-HD digital television and analog widescreen television PALplus. Japan's Hi-Vision originally started with a 5:3 (= 15:9) 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 standard. DVD producers can also choose to show even wider ratios such as 1.85:1 and 2.39:1[1] within the 16:9 DVD frame by hard matting or adding black bars within the image itself.
