In: Root » Computers and technology » Software
The relationship between the width and height of a monitor screen is termed its aspect ratio. Today the shape of the screen of nearly every monitor is standardized, as is that of the underlying CRT that makes the image. The screen is 1.33 times wider than it is high, resulting in the same 4:3 aspect ratio used in television and motion pictures before the wide screen phenomenon took over. Modern engineers now prefer to put the vertical number first to produce aspect ratios that are less than one. Expressed in this way, video has a 3:4 aspect ratio, a value of 0.75. The choice of aspect ratio is arbitrary and a matter of aesthetics. According to classical Greek aesthetics, the Golden Ratio with a value of about 0.618 is the most beautiful. This beauty is mathematical as well as aesthetic, the solution to the neat little equation x+1 = 1/x. The exact value of the Golden Ratio is irrational, (SQRT(5)-1)/2. Expressed as a ratio of horizontal to vertical, the Golden Ratio is roughly 1.618, the solution to x-1 = 1/x.) Various display systems feature their own aspect ratios. The modern tendency is toward wider aspect ratios. For example, High Definition Television (HDTV) stretches its aspect ration from the 3:4 of normal video and television to 9:15. The normal negatives you make with your 35mm camera have a 4:6 aspect ratio. The reason video is so nearly square carries over from the early days of television when cathode ray tubes had circular faces. The squarer the image, the more of the circular screen was put to use. The image on your monitor screen need not have the same aspect ratio of the tube, however. The electronics of monitors separate the circuitry that generates the horizontal and vertical scanning signals and results in their independent control. As a result, the relationship between the two can be adjusted, and that adjustment results in an alteration of the aspect ratio of the actual displayed image. For example, by increasing the amplification of the horizontal signal, the width of the image is stretched, raising the aspect ratio. Normally, you should expect that the relative gains of the horizontal and vertical signals will be adjusted so that your display shows the correct aspect ratio on its screen. A problem develops when a display tries to accommodate signals based on different standards. This mismatch is particularly troublesome with VGA displays because the VGA standard allows images made with three distinct line counts-350, 400, and 480. All else being equal, an image made from 350 lines is less than three-quarters the height of a 480-line image. A graphic generated in an EGA-compatible mode shown on a VGA display would therefore look quite squashed. A circle drawn on the screen would look like an ellipse; a orange would more resemble a watermelon.
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