Field (video)

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In video, 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 "interlaced" 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 interpolated 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.

Video electronic medium for the recording, copying and broadcasting of moving visual images

Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode ray tube (CRT) systems which were later replaced by flat panel displays of several types.

In filmmaking, video production, animation, and related fields, a frame is one of the many still images which compose the complete moving picture. The term is derived from the fact that, from the beginning of modern filmmaking toward the end of the 20th century, and in many places still up to the present, the single images have been recorded on a strip of photographic film that quickly increased in length, historically; each image on such a strip looks rather like a framed picture when examined individually.

Interlaced video technique for doubling the perceived frame rate of a video display without consuming extra bandwidth

Interlaced video is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth. The interlaced signal contains two fields of a video frame captured at two different times. This enhances motion perception to the viewer, and reduces flicker by taking advantage of the phi phenomenon.

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 scan video.

Progressive scanning is a format of displaying, storing, or transmitting moving images in which all the lines of each frame are drawn in sequence. This is in contrast to interlaced video used in traditional analog television systems where only the odd lines, then the even lines of each frame are drawn alternately, so that only half the number of actual image frames are used to produce video. The system was originally known as "sequential scanning" when it was used in the Baird 240 line television transmissions from Alexandra Palace, United Kingdom in 1936. It was also used in Baird's experimental transmissions using 30 lines in the 1920s. Progressive scanning is universally used in computer screens in the 2000s.

Video shot with a standard video camera format such as S-VHS or Mini-DV is often interlaced when created, whereas video shot with a film-based camera 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 tube (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). Most prosumer camcorders can record in progressive scan formats.

Video camera camera used for electronic motion picture acquisition

A video camera is a camera used for electronic motion picture acquisition, initially developed for the television industry but now common in other applications as well.

In video editing, it is crucial to know which of the two (odd or even) fields is "dominant." 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.

In video engineering, field dominance refers to the choice of which field of an interlaced video signal is chosen as the point at which video edits or switches occur.

See also

Federal Standard 1037C, titled Telecommunications: Glossary of Telecommunication Terms, is a United States Federal Standard issued by the General Services Administration pursuant to the Federal Property and Administrative Services Act of 1949, as amended.

In video engineering, color framing refers to the color frame sequence of fields in a composite video signal through which the video frame timing and chrominance subcarrier signal timing—in particular, that of the color burst -- cycle through all possible phase relationships.

Related Research Articles

Digital video is an electronic representation of moving visual images (video) in the form of encoded digital data. This is in contrast to analog video, which represents moving visual images with analog signals. Digital video comprises a series of digital images displayed in rapid succession.

Telecine

Telecine is the process of transferring motion picture film into video and is performed in a color suite. The term is also used to refer to the equipment used in the post-production process. Telecine enables a motion picture, captured originally on film stock, to be viewed with standard video equipment, such as television sets, video cassette recorders (VCR), DVD, Blu-ray Disc or computers. Initially, this allowed television broadcasters to produce programmes using film, usually 16mm stock, but transmit them in the same format, and quality, as other forms of television production. Furthermore, telecine allows film producers, television producers and film distributors working in the film industry to release their products on video and allows producers to use video production equipment to complete their filmmaking projects. Within the film industry, it is also referred to as a TK, because TC is already used to designate timecode.

A line doubler is a device used to deinterlace video signals prior to display.

Enhanced-definition television, or extended-definition television (EDTV) is an American Consumer Electronics Association (CEA) marketing shorthand term for certain digital television (DTV) formats and devices. Specifically, this term defines formats that deliver a picture superior to that of standard-definition television (SDTV) but not as detailed as high-definition television (HDTV).

Display resolution how many pixels a monitor can display

The display resolution or display modes of a digital television, computer monitor or display device is the number of distinct pixels in each dimension that can be displayed. It can be an ambiguous term especially as the displayed resolution is controlled by different factors in cathode ray tube (CRT) displays, flat-panel displays and projection displays using fixed picture-element (pixel) arrays.

Deinterlacing is the process of converting interlaced video, such as common analog television signals or 1080i format HDTV signals, into a non-interlaced form.

HDV

HDV is a format for recording of high-definition video on DV cassette tape. The format was originally developed by JVC and supported by Sony, Canon, and Sharp. The four companies formed the HDV consortium in September 2003.

720p

720p is a progressive HDTV signal format with 720 horizontal lines and an aspect ratio (AR) of 16:9, normally known as widescreen HDTV (1.78:1). All major HDTV broadcasting standards include a 720p format, which has a resolution of 1280×720; however, there are other formats, including HDV Playback and AVCHD for camcorders, that use 720p images with the standard HDTV resolution. The frame rate is standards-dependent, and for conventional broadcasting appears in 50 progressive frames per second in former PAL/SECAM countries, and 59.94 frames per second in former NTSC countries.

1080i is an abbreviation referring to a combination of frame resolution and scan type, used in high-definition television (HDTV) and high-definition video. The number "1080" refers to the number of horizontal lines on the screen. The "i" is an abbreviation for "interlaced"; this indicates that only the odd lines, then the even lines of each frame are drawn alternately, so that only half the number of actual image frames are used to produce video. A related display resolution is 1080p, which also has 1080 lines of resolution; the "p" refers to progressive scan, which indicates that the lines of resolution for each frame are "drawn" in on the screen sequence.

Flicker fixer

A flicker fixer or scan doubler is a piece of computer hardware that de-interlaces an output video signal. The flicker fixer accomplishes this by adjusting the timing of the natively interlaced video signal to suit the needs of a progressive display Ex: CRT computer monitor. Flicker fixers in essence create a progressive frame of video from two interlaced fields of video.

Film-out is the process in the computer graphics, video production and filmmaking disciplines of transferring images or animation from videotape or digital files to a traditional film print. "Film-out" is a broad term that encompasses the conversion of frame rates, color correction, as well as the actual printing, also called scanning or recording.

High-definition video is video of higher resolution and quality than standard-definition. While there is no standardized meaning for high-definition, generally any video image with considerably more than 480 vertical lines or 576 vertical lines (Europe) is considered high-definition. 480 scan lines is generally the minimum even though the majority of systems greatly exceed that. Images of standard resolution captured at rates faster than normal, by a high-speed camera may be considered high-definition in some contexts. Some television series shot on high-definition video are made to look as if they have been shot on film, a technique which is often known as filmizing.

1080p set of HDTV high-definition video

1080p is a set of HDTV high-definition video modes characterized by 1,920 pixels displayed across the screen horizontally and 1,080 pixels down the screen vertically; the p stands for progressive scan, i.e. non-interlaced. The term usually assumes a widescreen aspect ratio of 16:9, implying a resolution of 2.1 megapixels. It is often marketed as full HD, to contrast 1080p with 720p resolution screens.

Progressive segmented Frame is a scheme designed to acquire, store, modify, and distribute progressive scan video using interlaced equipment.

Flicker-free is a term given to video displays, primarily cathode ray tubes, operating at a high refresh rate to reduce or eliminate the perception of screen flicker. For televisions, this involves operating at a 100 Hz or 120 Hz hertz field rate to eliminate flicker, compared to standard televisions that operate at 50 Hz or 60 Hz (NTSC), most simply done by displaying each field twice, rather than once. For computer displays, this is usually a refresh rate of 70–90 Hz, sometimes 100 Hz or higher. This should not be confused with motion interpolation, though they may be combined – see implementation, below.

Raster scan

A raster scan, or raster scanning, is the rectangular pattern of image capture and reconstruction in television. By analogy, the term is used for raster graphics, the pattern of image storage and transmission used in most computer bitmap image systems. The word raster comes from the Latin word rastrum, which is derived from radere ; see also rastrum, an instrument for drawing musical staff lines. The pattern left by the lines of a rake, when drawn straight, resembles the parallel lines of a raster: this line-by-line scanning is what creates a raster. It is a systematic process of covering the area progressively, one line at a time. Although often a great deal faster, it is similar in the most-general sense to how one's gaze travels when one reads lines of text.