Aspect ratio describes the dimensions of video screens & video picture elements. All popular video formats are rectilinear, & so can be described by a ratio between width & height. The screen aspect ratio of a traditional tv screen is four:3, or about one.33:1. High definition televisions use a facet ratio of 16:9, or about one.78:1. The aspect ratio of a full 35 mm film frame with soundtrack (also known as the Academy ratio) is one.375:1.
Ratios where height is taller than width are unusual in general everyday use, but are used in computer systems where some applications are better suited for a vertical layout. The most common tall aspect ratio of three:4 is known as portrait mode & is created by physically rotating the display tool 90 degrees from the normal position. Other tall aspect ratios such as 9:16 are technically feasible but seldom used. (For a detailed discussion of this topic, see page orientation.)
Pixels on computer monitors are usually square, but pixels used in digital video often have non-square aspect ratios, such as those used in the PAL & NTSC variants of the CCIR 601 digital video standard, & the corresponding anamorphic widescreen formats. Therefore, a 720 by 480 pixel NTSC DV picture displayes with the four:3 aspect ratio (the traditional tv standard) if the pixels are narrow, & displays at the 16:9 aspect ratio (the anamorphic widescreen format) if the pixels are fat.
Ratios where height is taller than width are unusual in general everyday use, but are used in computer systems where some applications are better suited for a vertical layout. The most common tall aspect ratio of three:4 is known as portrait mode & is created by physically rotating the display tool 90 degrees from the normal position. Other tall aspect ratios such as 9:16 are technically feasible but seldom used. (For a detailed discussion of this topic, see page orientation.)
Pixels on computer monitors are usually square, but pixels used in digital video often have non-square aspect ratios, such as those used in the PAL & NTSC variants of the CCIR 601 digital video standard, & the corresponding anamorphic widescreen formats. Therefore, a 720 by 480 pixel NTSC DV picture displayes with the four:3 aspect ratio (the traditional tv standard) if the pixels are narrow, & displays at the 16:9 aspect ratio (the anamorphic widescreen format) if the pixels are fat.
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