In
videoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.-History:...
, a
field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame. When the fields are displayed on a video monitor they are "
interlacedIn the domain of mechanical television, the concept of interlacing was demonstrated by Léon Theremin. He had been developing a mirror drum-based television, starting with 16 lines resolution in 1925, then 32 lines and eventually 64 using interlacing in 1926, and as part of his thesis on May 7, 1926...
" so that the content of one field will be used on all of the odd-numbered lines on the screen and the other field will be displayed on the even lines. Converting fields to a still frame image requires a process called deinterlacing, in which the missing lines are duplicated or
interpolatedIn the mathematical subfield of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....
to recreate the information that would have been contained in the discarded field.
In
videoVideo is the technology of electronically capturing, recording, processing, storing, transmitting, and reconstructing a sequence of still images representing scenes in motion.-History:...
, a
field is one of the many still images which are displayed sequentially to create the impression of motion on the screen. Two fields comprise one video frame. When the fields are displayed on a video monitor they are "
interlacedIn the domain of mechanical television, the concept of interlacing was demonstrated by Léon Theremin. He had been developing a mirror drum-based television, starting with 16 lines resolution in 1925, then 32 lines and eventually 64 using interlacing in 1926, and as part of his thesis on May 7, 1926...
" so that the content of one field will be used on all of the odd-numbered lines on the screen and the other field will be displayed on the even lines. Converting fields to a still frame image requires a process called deinterlacing, in which the missing lines are duplicated or
interpolatedIn the mathematical subfield of numerical analysis, interpolation is a method of constructing new data points within the range of a discrete set of known data points....
to recreate the information that would have been contained in the discarded field. Since each field contains only half of the information of a full frame, however, deinterlaced images do not have the resolution of a full frame.
In order to increase the resolution of video images, therefore, new schemes have been created that capture full-frame images for each frame. Video composed of such frames is called
progressive scanProgressive or noninterlaced scanning is a method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence...
video.
Video shot with a standard
video cameraA video camera is a camera used for electronic motion picture acquisition, initially developed by the television industry but now common in other applications as well. The earliest video cameras were those of John Logie Baird, based on the electromechanical Nipkow disk and used by the BBC in...
format such as S-VHS or Mini-DV is often interlaced when created, whereas video shot with a
film-based cameraFilm encompasses individual motion pictures, the field of film as an art form, and the motion picture industry. Films are produced by recording images from the world with cameras, or by creating images using animation techniques or visual effects....
is almost always progressive. Free-to-air analog TV was mostly broadcast as interlaced material because the trade-off of spatial resolution for frame-rate reduced flickering on
Cathode ray tubeThe cathode ray tube is a vacuum tube containing an electron gun and a fluorescent screen, with internal or external means to accelerate and deflect the electron beam, used to create images in the form of light emitted from the fluorescent screen...
(CRT) televisions. High-definition digital television (see: HDTV) today can be broadcast terrestrially or distributed through cable system in either interlaced (1080i) or progressive scan formats (720p or 1080p). There are now some prosumer
HDVHDV is a format for recording and playback of high-definition video on a DV cassette tape. The format was originally developed by JVC and was supported by Sony, Canon and Sharp. The four companies formed the in September 2003...
camcorders that can shoot in progressive scan (720p) formats.
In video editing, it is crucial to know which of the two (odd or even) fields is "
dominantIn video engineering, field dominance refers to the choice of which field of an interlaced video videosignal is chosen as the point at which video edits occur. There are only two choices for field dominance in normal interlaced video: odd or even. Interlacing divides the frame into two fields,...
." Selecting edit points on the wrong field can result in a "flash" at each edit point and playing the video fields in reverse order creates a flickering image.
External links