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Next: 5.5 Miscellaneous issues Up: 5 Differences Between Computer Previous: 5.3 Colour

5.4 Resolution and aspect ratio

The resolution of a given system is the dimensions in pixels of the displayed image, and the aspect ratio is the ratio of width to height. The resolution is a major factor in image quality, and aspect ratio must be preserved when transferring images to prevent them from becoming distorted.

Most video and graphics systems share the same aspect ratio, 4:3. This removes some of the complexity when transferring images, and even when aspect ratios differ the technique of letterboxing may be used to add black borders when neccessary to preserve the aspect ratio of the original image.

PAL has a 625 line frame, however, 8% of this is used for synchronisation14, and this gives an effective resolution of 768 x 576. NTSC has a 525 line frame, but again 8% is used for synchronisation, giving an effective resolution of 640 x 480. Typical computer graphics frame resolutions are 640 x 480, 800 x 600, 1024 x 768, 1152 x 864, 1280 x 1024 and 1600 x 1200.

Kevin Pulo