What is interlacing ?
Typical PC VGA display uses progressive scanning (also called “non-interlaced”). In this mode the screen is refreshed from up left corner to right bottom corner so that every scanline is scanned in every screen refresh. The picture below shows how progressive scannign works: Progressive scanning Progressive scanning is very good in computer display because it gives a stable display when the refresh rate is high enough. The drawback of the progressive scanning is the high video bandwidth needed for screen updated (not usually problem in computer display systems nowadays). In the sutuations, where the bandwidth is limited, interlaced scanning can give almost as good picture with less bandwidth. For example normal TV uses interlaced scanning. The picture below shows how the interlaced scannign works: Interlaced scanning In interlaced scanning mode, every screen refresh draws only half of the scanlines (every other scanline).
Typical PC VGA display uses progressive scanning (also called “non-interlaced”). In this mode the screen is refreshed from up left corner to right bottom corner so that every scanline is scanned in every screen refresh. The picture below shows how progressive scannign works: Progressive scanning is very good in computer display because it gives a stable display when the refresh rate is high enough. The drawback of the progressive scanning is the high video bandwidth needed for screen updated (not usually problem in computer display systems nowadays). In the sutuations, where the bandwidth is limited, interlaced scanning can give almost as good picture with less bandwidth. For example normal TV uses interlaced scanning. The picture below shows how the interlaced scannign works: In interlaced scanning mode, every screen refresh draws only half of the scanlines (every other scanline). For exmaple in PAL TV in this way screen can be updated (only half of the scanlines) 50 times a second us
