What is interlacing
TV video signal is interlaced
A TV video signal is interlaced, meaning each full screen of information is actually made up of two separate fields—the odd field and the even field. First, the odd lines are painted on the screen. Then, before the odd lines fade, the even lines are painted in between the odd lines. This all happens faster than the human eye can perceive.
Computer signal is noninterlaced
In contrast, the computer signal is noninterlaced—the horizontal lines are painted progressively, left to right, top to bottom, in a single pass. So the flickering problem you get in interlaced TV does not exist in computer video.
Line doublers and quadruplers were developed to convert interlaced TV signals to noninterlaced computer signals. However, when compared to line doublers or quadruplers, both video scalers offer several clear advantages: