SD (Standard Definition)

Video image with a resolution defined in standards popularized in the 1950s and widely used for television around the world. For 60-Hz NTSC systems, the video image is composed of 525 interlaced horizontal lines, of which 485 represent the actual image. For 50-Hz PAL systems, the video image is composed of 625 interlaced horizontal lines, of which 576 represent the actual image. Both of these standards use a 4:3 aspect ratio.