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The Indian-head test pattern is a test card that gained widespread adoption during the black-and-white television broadcasting era as an aid in the calibration of television equipment. It features a drawing of a Native American wearing a headdress surrounded by numerous graphic elements designed to test different aspects of broadcast display. The card was created by RCA to be the standard image for their TK-1 monoscope, a simple video camera capable of producing only the image embedded within it. The pattern was introduced in 1939 and over the following two decades became a fixture of television broadcast across North America in 525-line resolution and (often in modified form) abroad in 525- and 625-line resolution until it was obsoleted by the rise of color television in the 1960s.
The Indian-head test pattern was created by RCA at their factory in Harrison, New Jersey. Each element of the card was designed to measure a specific technical aspect of television broadcast so that an experienced engineer could, at a glance, identify problems. The card contains elements used to measure aspect ratio, [lower-alpha 1] perspective, framing, linearity, frequency response, differential gain, contrast, and brightness. The grid and circles were used for perspective, framing and linearity. The tapered lines (marked with 20, 25, 30, and 35) were used for resolution and frequency response. The thin lines marked from 575 to 325 on one side and 300 to 50 on the other side referred to lines of resolution. The gray bands emerging from the center off to the lower right and upper left were for differential gain, contrast, and white level.
The pattern began with the Indian-head portrait created in August 1938 by an artist named Brooks using pencil, charcoal, ink and zinc oxide. [1] For about a year, the portrait (which contains several identifiable shades of gray from Zone VIII texture in the white feathers to Zone II texture in the black hair) was the entire test pattern, but in 1939 the portrait was incorporated into the current pattern of calibrated lines and shapes.
Television stations would produce the image of the Indian-head test pattern in two ways. First, they would use a monoscope in which the pattern was permanently embedded, which was capable of producing the image with a high degree of consistency due to the device's simplicity. The monoscope tube is constructed similarly to a small cathode ray tube (CRT), but instead of displaying an image, it scans a built-in image, producing a video signal. The tube has a perfectly proportioned copy of the test pattern master art (or a modified variant with the station ID replacing the Indian-head portrait, such as those used by KRLD-TV, [2] WBAP-TV [3] and WKY-TV [4] ) inside, permanently deposited as a carbon image on an aluminum target plate or slide. The target plate is sequentially scanned with a focused beam of electrons, which were originally called cathode rays . When the electron beam strikes the carbon image areas, the carbon resists current flow, and the resulting lower electron current flow is adjusted to appear as video black. When the electron beam strikes the metallic-aluminum image areas, there is less resistance with higher current flow, and the resulting higher electron current flow is adjusted to appear as video white. This image was used to calibrate monitors in the station. Second, stations would use a cardboard-mounted lithograph of the test pattern (typically attached to a rolling easel in each TV studio); videographing the lithograph would create a second image that could be compared against the monoscope-created control image.
The test pattern was useful for the calibration of home television sets as well as television studio equipment, so the image was routinely broadcast outside hours of programming. [5] (It was often accompanied by an audio test tone for the purposes of calibrating aural system frequency response measurements. [6] )
From the late 1950s the test pattern gradually began to be seen less frequently, after fewer sign-offs, on fewer stations, and for shorter periods in the morning, since new and improved TV broadcast equipment required less adjusting. In later years the test pattern was transmitted for as little as a minute after sign-off while the transmitter engineer logged required Federal Communications Commission-US/Board of Broadcast Governors transmitter readings before cutting power.[ citation needed ]
The Indian-head test pattern became obsolete in the 1960s with the debut of color television; from that point onward, an alternate test card of SMPTE color bars (and its immediate predecessors), or colorized versions of the NBC/CBS-derived "bullseye" patterns became the test card of choice. Since the 1990s, most television stations in the United States have broadcast continuously without regular sign-offs, instead running infomercials, networked overnight news shows, syndicated reruns, cartoons, or old movies; thus, the broadcast of test patterns has become mostly obsolete (though they are still used in post-production and broadcast facilities to check color and signal paths).
Nevertheless, the Indian-head test pattern persists as a symbol of early television. Many U.S. television stations chose the image of the Indian-head card to be their final image broadcast when their analog signals signed off for the final time between February 17 and June 12, 2009, as part of the digital television transition in the United States. [7] [8] [ unreliable source? ] [9] [ unreliable source? ]
A variant of the card appeared on the Canadian sketch comedy show Second City Television in the late-1970s, [10] and another variant appeared on theatrical release posters for "Weird Al" Yankovic's 1989 film UHF . Some Pioneer GGV1069 LaserDisc reference discs released for the NTSC market included a variant of the card, but modified with a gray-colored grid and a drawing of a Japanese lion-dog replacing the Indian-head portrait. [11] [12] It was sold as a night-light from 1997 to 2005 by the Archie McPhee company, [13] reminiscent of the times when a fairly common late-night experience was to fall asleep while watching the late movie, only to awaken to the characteristic sine wave tone accompanying the Indian-head test pattern on a black-and-white TV screen. The test card also featured in the opening sequence of the early 1960s science fiction anthology The Outer Limits . [14]
Nearly all of the hard-to-open, steel-shielded monoscope tubes were junked with their Indian-head test pattern target plates still inside, but many of the board-mounted lithographs survive.
The master art for both the portrait and the pattern design was discovered in a dumpster by a wrecking crew worker as the old RCA factory in Harrison, New Jersey was being demolished in 1970. The worker kept the art for over 30 years before selling it to a collector. [1]
The Indian head was also used by the Canadian Broadcasting Corporation (CBC) [15] in Canada in conjunction with its own monochrome test pattern, [16] following the Canadian national anthem sign-off in the evening, and during its final years in the late-1970s and early-1980s it was shown before sign-on in the morning, after the showing of the SMPTE color bars. [17]
It was also used by Rhodesia Television (RTV) during British colonial times (varying between Northern and Southern Rhodesia) following the playing of "God Save the Queen" at closedown.
This test pattern was later used by the Venezuelan TV channel Venevisión, in conjunction with the RMA Resolution Chart 1946, until the late-1970s before signing on with the Venezuelan national anthem. Telesistema Mexicano (now Televisa) stations also used this test pattern until the late-1960s immediately after playing the Mexican national anthem at sign-off.
In the Dominican Republic, the Indian-head pattern was used by its public broadcaster Corporación Estatal de Radio y Televisión (CERTV) in the late-1960s and 1970s (in conjunction with the EIA 1956 resolution chart test card) after playing the National Anthem of the Dominican Republic at sign-off.
In Sweden, the Indian-head test pattern was used in test transmissions from the KTH Royal Institute of Technology [19] in Stockholm alongside the RMA Resolution Chart 1946, Telefunken T05 test card, as well as other experimental test cards from Televerket and Chalmers University of Technology from 1948 until November 1958 when it was replaced by the Sveriges Radio TV (now Sveriges Television) test card. [20] [21]
In Australia, the Indian-head test pattern was used by TNT-9 in Northern Tasmania in conjunction with the Marconi Resolution Chart No. 1 from its launch in 1962 until it adopted colour television in the mid-1970s. This version eschewed the Indian head drawing with the TNT-9 station ID on top, similar to the aforementioned KRLD-TV, WBAP-TV and WKY-TV variants. [22]
Saudi Broadcasting Authority in Saudi Arabia also formerly used a modified version of the Indian-head test pattern, with the Emblem of Saudi Arabia replacing the Indian head drawing, [23] [24] [ unreliable source? ] from 1954 until 1982 when it was replaced with a heavily modified Philips PM5544 test card.
The Indian head was also used in Brazil by Rede Tupi, both as a test pattern and as part of a television ident, from its launch in 1950 until it became the first Brazilian television network to adopt colour television in 1971–72.
The Indian head pattern was also used by Kuwait Television in Kuwait from its launch of television services in 1961 until it adopted colour television in the mid-1970s.
In Italy, the pattern was adapted and modified by RAI for its monochrome test cards, used from 1961 to 1977. [25] [26] [27]
Analog television is the original television technology that uses analog signals to transmit video and audio. In an analog television broadcast, the brightness, colors and sound are represented by amplitude, phase and frequency of an analog signal.
NTSC is the first American standard for analog television, published in 1941. In 1961, it was assigned the designation System M. It is also known as EIA standard 170.
Phase Alternating Line (PAL) is a colour encoding system for analog television. It was one of three major analogue colour television standards, the others being NTSC and SECAM. In most countries it was broadcast at 625 lines, 50 fields per second, and associated with CCIR analogue broadcast television systems B, D, G, H, I or K. The articles on analog broadcast television systems further describe frame rates, image resolution, and audio modulation.
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 consecutively. This enhances motion perception to the viewer, and reduces flicker by taking advantage of the characteristics of the human visual system.
Color television or colour television is a television transmission technology that includes color information for the picture, so the video image can be displayed in color on the television set. It improves on the monochrome or black-and-white television technology, which displays the image in shades of gray (grayscale). Television broadcasting stations and networks in most parts of the world upgraded from black-and-white to color transmission between the 1960s and the 1980s. The invention of color television standards was an important part of the history and technology of television.
A test card, also known as a test pattern or start-up/closedown test, is a television test signal, typically broadcast at times when the transmitter is active but no program is being broadcast.
SMPTE color bars are a television test pattern used where the NTSC video standard is utilized, including countries in North America. The Society of Motion Picture and Television Engineers (SMPTE) refers to the pattern as Engineering Guideline (EG) 1-1990. Its components are a known standard, and created by test pattern generators. Comparing it as received to the known standard gives video engineers an indication of how an NTSC video signal has been altered by recording or transmission and what adjustments must be made to bring it back to specification. It is also used for setting a television monitor or receiver to reproduce NTSC chrominance and luminance information correctly.
Broadcasttelevision systems are the encoding or formatting systems for the transmission and reception of terrestrial television signals.
A professional video camera is a high-end device for creating electronic moving images. Originally developed for use in television studios or with outside broadcast trucks, they are now also used for music videos, direct-to-video movies, corporate and educational videos, wedding videos, among other uses. Since the 2000s, most professional video cameras are digital.
U-matic or 3⁄4-inch Type E Helical Scan or SMPTE E is an analogue recording videocassette format first shown by Sony in prototype in October 1969, and introduced to the market in September 1971. It was among the first video formats to contain the videotape inside a cassette, as opposed to the various reel-to-reel or open-reel formats of the time. The videotape is 3⁄4 in (19 mm) wide, so the format is often known as "three-quarter-inch" or simply "three-quarter", compared to open reel videotape formats in use, such as 1 in (25 mm) type C videotape and 2 in (51 mm) quadruplex videotape.
A monoscope was a special form of video camera tube which displayed a single still video image. The image was built into the tube, hence the name. The tube resembled a small cathode ray tube (CRT). Monoscopes were used beginning in the 1950s to generate TV test patterns and station logos. This type of test card generation system was technologically obsolete by the 1980s.
The Philips circle pattern refers to a family of related electronically generated complex television station colour test cards. The content and layout of the original colour circle pattern was designed by Danish engineer Finn Hendil (1939–2011) in the Philips TV & Test Equipment laboratory in Amager near Copenhagen under supervision of chief engineer Erik Helmer Nielsen in 1966–67, largely building on their previous work with the monochrome PM5540 pattern. The first piece of equipment, the PM5544 colour pattern generator, which generates the pattern, was made by Finn Hendil and his group in 1968–69. The same team would also develop the Spanish TVE colour test card in 1973.
The Kell factor, named after RCA engineer Raymond D. Kell, is a parameter used to limit the bandwidth of a sampled image signal to avoid the appearance of beat frequency patterns when displaying the image in a discrete display device, usually taken to be 0.7. The number was first measured in 1934 by Raymond D. Kell and his associates as 0.64 but has suffered several revisions given that it is based on image perception, hence subjective, and is not independent of the type of display. It was later revised to 0.85 but can go higher than 0.9, when fixed pixel scanning and fixed pixel displays are used, or as low as 0.7 for electron gun scanning.
The Apollo program used several television cameras in its space missions in the late 1960s and 1970s; some of these Apollo TV cameras were also used on the later Skylab and Apollo–Soyuz Test Project missions. These cameras varied in design, with image quality improving significantly with each successive model. Two companies made these various camera systems: RCA and Westinghouse. Originally, these slow-scan television (SSTV) cameras, running at 10 frames per second (fps), produced only black-and-white pictures and first flew on the Apollo 7 mission in October 1968. A color camera – using a field-sequential color system – flew on the Apollo 10 mission in May 1969, and every mission after that. The color camera ran at the North American standard 30 fps. The cameras all used image pickup tubes that were initially fragile, as one was irreparably damaged during the live broadcast of the Apollo 12 mission's first moonwalk. Starting with the Apollo 15 mission, a more robust, damage-resistant camera was used on the lunar surface. All of these cameras required signal processing back on Earth to make the frame rate and color encoding compatible with analog broadcast television standards.
MUSE, commercially known as Hi-Vision was a Japanese analog high-definition television system, with design efforts going back to 1979.
High-definition television (HDTV) describes a television or video system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since at least 1933; in more recent times, it refers to the generation following standard-definition television (SDTV). It is the standard video format used in most broadcasts: terrestrial broadcast television, cable television, satellite television.
625-line is a late 1940s European analog standard-definition television resolution standard. It consists of a 625-line raster, with 576 lines carrying the visible image at 25 interlaced frames per second. It was eventually adopted by countries using 50 Hz utility frequency as regular TV broadcasts resumed after World War II. With the introduction of color television in the 1960s, it became associated with the PAL and SECAM analog color systems.
Beam deflection tubes, sometimes known as sheet beam tubes, are vacuum tubes with an electron gun, a beam intensity control grid, a screen grid, sometimes a suppressor grid, and two electrostatic deflection electrodes on opposite sides of the electron beam that can direct the rectangular beam to either of two anodes in the same plane.
525-line is an American standard-definition television resolution used since July 1, 1941, mainly in the context of analog TV broadcast systems. It consists of a 525-line raster, with 480 lines carrying the visible image at 30 interlaced frames per second. It was eventually adopted by countries using 60 Hz utility frequency as TV broadcasts resumed after World War II. With the introduction of color television in the 1950s, it became associated with the NTSC analog color standard.
The TVE colour test card was an electronic analogue TV test card adopted by Televisión Española with the introduction of PAL colour broadcasts in 1975. It is notable for its unique design, created by the Danish engineer Finn Hendil (1939–2011) in 1973, under the supervision of Erik Helmer Nielsen at the Philips TV & Test Equipment laboratory in Amager, south of Copenhagen, the same team that developed the popular Philips PM5544 test pattern. It replaced a previous black and white version developed by Eduardo Gavilán.
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