Editing Video (section)

===Interlaced vs. progressive===
Video can be [[interlaced]] or [[Progressive scan|progressive]]. In progressive scan systems, each refresh period updates all scan lines in each frame in sequence. When displaying a natively progressive broadcast or recorded signal, the result is the optimum spatial resolution of both the stationary and moving parts of the image. Interlacing was invented as a way to reduce flicker in early [[mechanical television|mechanical]] and [[cathode-ray tube|CRT]] video displays without increasing the number of complete [[frames per second]]. Interlacing retains detail while requiring lower [[Bandwidth (signal processing)|bandwidth]] compared to progressive scanning.<ref name=":0">{{Cite book |last=Bovik |first=Alan C. |url=https://www.worldcat.org/oclc/190789775 |title=Handbook of image and video processing |date=2005 |publisher=Elsevier Academic Press |isbn=978-0-08-053361-2 |edition=2nd |location=Amsterdam |pages=14–21 |oclc=190789775 |access-date=August 25, 2022 |archive-date=August 25, 2022 |archive-url=https://web.archive.org/web/20220825123924/https://www.worldcat.org/title/190789775 |url-status=live }}</ref><ref name=":1">{{Cite book |last=Wright |first=Steve |url=https://www.worldcat.org/oclc/499054489 |title=Digital compositing for film and video |date=2002 |publisher=Focal Press |isbn=978-0-08-050436-0 |location=Boston |oclc=499054489 |access-date=August 25, 2022 |archive-date=August 25, 2022 |archive-url=https://web.archive.org/web/20220825123924/https://www.worldcat.org/title/499054489 |url-status=live }}</ref>

In interlaced video, the horizontal [[scan line]]s of each complete frame are treated as if numbered consecutively and captured as two ''fields'': an ''odd field'' (upper field) consisting of the odd-numbered lines and an ''even field'' (lower field) consisting of the even-numbered lines. Analog display devices reproduce each frame, effectively doubling the frame rate as far as perceptible overall flicker is concerned. When the image capture device acquires the fields one at a time, rather than dividing up a complete frame after it is captured, the frame rate for motion is effectively doubled as well, resulting in smoother, more lifelike reproduction of rapidly moving parts of the image when viewed on an interlaced CRT display.<ref name=":0" /><ref name=":1" />

NTSC, PAL, and SECAM are interlaced formats.  Abbreviated video resolution specifications often include an ''i'' to indicate interlacing. For example, PAL video format is often described as ''576i50'', where ''576'' indicates the total number of horizontal scan lines, ''i'' indicates interlacing, and ''50'' indicates 50 fields (half-frames) per second.<ref name=":1" /><ref name=":2">{{Cite book |last=Brown |first=Blain |title=Cinematography: Theory and Practice: Image Making for Cinematographers and Directors |publisher=[[Taylor & Francis]] |year=2013 |isbn=9781136047381 |pages=159–166}}</ref>

When displaying a natively interlaced signal on a progressive scan device, the overall spatial resolution is degraded by simple [[line doubling]]—artifacts, such as flickering or "comb" effects in moving parts of the image, appear unless special signal processing eliminates them.<ref name=":0" /><ref name=":3">{{Cite book |last=Parker |first=Michael |url=https://www.worldcat.org/oclc/815408915 |title=Digital Video Processing for Engineers : a Foundation for Embedded Systems Design |date=2013 |others=Suhel Dhanani |isbn=978-0-12-415761-3 |location=Amsterdam |oclc=815408915 |access-date=August 25, 2022 |archive-date=August 25, 2022 |archive-url=https://web.archive.org/web/20220825123924/https://www.worldcat.org/title/815408915 |url-status=live }}</ref> A procedure known as [[deinterlacing]] can optimize the display of an interlaced video signal from an analog, DVD, or satellite source on a progressive scan device such as an [[LCD television]], digital [[video projector]], or plasma panel. Deinterlacing cannot, however, produce [[video quality]] that is equivalent to true progressive scan source material.<ref name=":1" /><ref name=":2" /><ref name=":3" />