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Color television
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Color television refers to the technology and practices associated with television's transmission of moving images in color.
successful transmission of color images was hindered in television's mechanical era by the sluggish response of selenium photoelectric cells at the transmitting end; to get around this, early color systems typically used three separate scanning, transmission, and reproduction systems that were superimposed into one image at the receiver.
Among the earliest published proposals for television was one by Maurice Le Blanc in 1880 for a color system, including the first mentions in television literature of line and frame scanning, although he gave no practical details.
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Encyclopedia
Color television refers to the technology and practices associated with television's transmission of moving images in color.
Mechanical color
The successful transmission of color images was hindered in television's mechanical era by the sluggish response of selenium photoelectric cells at the transmitting end; to get around this, early color systems typically used three separate scanning, transmission, and reproduction systems that were superimposed into one image at the receiver.
Among the earliest published proposals for television was one by Maurice Le Blanc in 1880 for a color system, including the first mentions in television literature of line and frame scanning, although he gave no practical details. Polish inventor Jan Szczepanik patented a color television system in 1897, using a selenium photoelectric cell at the transmitter and an electromagnet controlling an oscillating mirror and a moving prism at the receiver. But his system contained no means of analyzing the spectrum of colors at the transmitting end, and could not have worked as he described it. An experimental color television was demonstrated in London in 1928 based on Hovannes Adamian's tricolor principle.
John Logie Baird demonstrated the world's first color transmission on July 3, 1928, using scanning discs at the transmitting and receiving ends with three spirals of apertures, each spiral with filters of a different primary color; and three light sources at the receiving end, with a commutator to alternate their illumination. Baird also made the world's first color broadcast on February 4 1938, sending a mechanically scanned 120-line image from Baird's Crystal Palace studios to a projection screen at London's Dominion Theatre.
In 1939, Hungarian engineer Peter Carl Goldmark invented a Field-sequential color system while at CBS. The system, first demonstrated on August 29, 1940, and shown to the press on September 3rd used a rapidly rotating color wheel that alternated transmission in red, green and blue. The system transmitted on 343 lines, about 100 less than a black and white set, and thus was incompatible with most television sets currently on the market. . Although CBS did broadcast in color with the Goldmark system in 1951, the "compatible color" technology developed for RCA and NBC (by a team led by Richard Kell, George H. Brown and others) was compatible with existing black and white TVs. Goldmark and others have pointed out that the CBS color wheel system did provide better picture quality than RCA's system, but the compatibility problem proved its downfall. As a result, the RCA/NBC color system became the industry standard chosen by the FCC in 1953. Cameras using the color wheel system continued to be used for scientific research for several more decades, including at least one of the 1970s NASA moon landings.
Electronic color
In 1938 the shadow mask color television was patented by Werner Flechsig in Germany, and was demonstrated at the International radio exhibition Berlin in 1939. Most CRT color televisions used today are based on this technology. On August 16, 1944, Baird gave the first demonstration of a fully electronic color television display. His 600-line color system used triple interlacing, using six scans to build each picture.
Color standards
There are three main standards in use around the world, PAL (Phase Alternating Line), NTSC (National Television System Committee) and SECAM (Séquentiel Couleur à Mémoire—Sequential Color with Memory).
The system used in North America is NTSC. Western Europe, Australia, and Eastern South America use PAL. Eastern Europe used SECAM, but switched to PAL after the change of the political regimes there. France still uses SECAM. Generally, a device (such as a television) can only read or display video encoded to a standard which the device is designed to support; otherwise, the source must be converted (such as when European programs are broadcast in North America or vice versa). Because a tint control is unnecessary in PAL, NTSC has jokingly been said to stand for Never Twice the Same Color.
This table illustrates the differences:
| NTSC M | PAL B,G,H | PAL I | PAL N | PAL M | SECAM B,G,H | SECAM D,K,K',L |
|---|
| Lines/Fields | 525/60 | 625/50 | 625/50 | 625/50 | 525/60 | 625/50 | 625/50 | | Horizontal Frequency | 15.734 kHz | 15.625 kHz | 15.625 kHz | 15.625 kHz | 15.750 kHz | 15.625 kHz | 15.625 kHz | | Vertical Frequency | 60 Hz | 50 Hz | 50 Hz | 50 Hz | 60 Hz | 50 Hz | 50 Hz | | Color Subcarrier Frequency | 3.579545 MHz | 4.43361875 MHz | 4.43361875 MHz | 3.582056 MHz | 3.575611 MHz | | | | Video Bandwidth | 4.2 MHz | 5.0 MHz | 5.5 MHz | 4.2 MHz | 4.2 MHz | 5.0 MHz | 6.0 MHz | | Sound Carrier | 4.5 MHz | 5.5 MHz | 5.9996 MHz | 4.5 MHz | 4.5 MHz | 5.5 MHz | 6.5 MHz |
History and adoption
North America
United States
Color television in the United States had a protracted history due to conflicting technical systems vying for approval by the Federal Communications Commission for commercial use. Mechanically scanned color television was demonstrated by Bell Laboratories in June 1929 using three complete systems of photoelectric cells, amplifiers, glow-tubes, and color filters, with a series of mirrors to superimpose the red, green, and blue images into one full color image.
In the electronically scanned era, the first color television demonstration was on February 5, 1940, when RCA privately showed to members of the FCC at the RCA plant in Camden, New Jersey, a television receiver producing color images by optically combining the images from two picture tubes onto a single rear-projection screen. CBS began experimental color field tests using film as early as August 28, 1940, and live cameras by November 12. The CBS field-sequential color system was partly mechanical, with a disc made of red, blue, and green filters spinning inside the television camera at 1,200 rpm, and a similar disc spinning in synchronization in front of the cathode ray tube inside the receiver set. RCA's later "dot sequential" color system had no moving parts, using a series of dichroic mirrors to separate and direct red, green, and blue light from the subject through three separate lenses into three scanning tubes, and electronic switching that allowed the tubes to send their signals in rotation, dot by dot. These signals were sorted by a second switching device in the receiver set and sent to red, green, and blue picture tubes, and combined by a second set of dichroic mirrors into a full color image.
NBC (owned by RCA) made its first field test of color television on February 20, 1941. CBS began daily color field tests on June 1, 1941. These color systems were not compatible with existing black and white television sets, and as no color television sets were available to the public at this time, viewership of the color field tests was limited to RCA and CBS engineers and the invited press. The War Production Board halted the manufacture of television and radio equipment for civilian use from April 22, 1942 to August 20, 1945, limiting any opportunity to introduce color television to the general public.
The post-war development of color television was dominated by three systems competing for approval by the FCC as the U.S. color broadcasting standard: CBS's field-sequential color system, which was incompatible with existing black and white sets without an adapter; RCA's dot sequential system, which in 1949 became compatible with existing black and white sets; and CTI's system (also incompatible with existing black and white sets), which used three camera lenses, behind which were color filters that produced red, green, and blue images side by side on a single scanning tube, and a receiver set that used lenses in front of the picture tube (which had sectors treated with different phosphorescent compounds to glow in red, green, or blue) to project these three side by side images into one combined picture on the viewing screen.
During its campaign for FCC approval, CBS gave the first demonstrations of color television to the American general public, showing an hour of color programs daily Mondays through Saturdays, beginning January 12, 1950, and running for the remainder of the month, over WOIC in Washington, D.C., where they could be viewed on eight 16-inch color receivers in a public building. Due to high public demand, the broadcasts were resumed February 13–21, with several evening programs added. CBS initiated a limited schedule of color broadcasts from its New York station WCBS-TV Mondays to Saturdays beginning November 14, 1950, making ten color receivers available for the viewing public. All were broadcast using the single color camera that CBS owned. The New York broadcasts were extended by coaxial cable to Philadelphia's WCAU-TV beginning December 13.
After a series of hearings beginning in September 1949, the FCC found the RCA and CTI systems fraught with technical problems, inaccurate color reproduction, and expensive equipment, and so formally approved the CBS system as the U.S. color broadcasting standard on October 11 1950. An unsuccessful lawsuit by RCA delayed the world's first network commercial broadcast in color until June 25 1951, when a musical variety special titled simply Premiere was shown over a network of five east coast CBS affiliates. Viewership was again extremely limited: the program could not be seen on black and white sets, and Variety estimated that only thirty prototype color receivers were available in the New York area. Regular color broadcasts began that same week with the daytime series The World Is Yours and Modern Homemakers.
While the CBS color broadcasting schedule gradually expanded to twelve hours per week (but never into prime time), and the color network expanded to eleven affiliates as far west as Chicago, its commercial success was doomed by the lack of color receivers necessary to watch the programs, the refusal of television manufacturers to create adapter mechanisms for their existing black and white sets, and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. CBS had bought a television manufacturer in April, and in September 1951, production began on the only CBS-Columbia color television model. But it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS discontinued its color television system on October 20, 1951, ostensibly by request of the National Production Authority for the duration of the Korean conflict, and bought back all the CBS color sets it could to prevent lawsuits by disappointed customers.
Starting before CBS color even got on the air, the U.S. television industry, represented by the National Television System Committee, worked in 1950–1953 to develop a color system that was compatible with existing black and white sets and would pass FCC quality standards, with RCA developing the hardware elements. RCA first made publicly announced field tests of the dot sequential color system over its New York station WNBT in July 1951. When CBS testified before Congress in March 1953 that it had no further plans for its own color system, the National Production Authority dropped its ban on the manufacture of color television receivers, and the path was open for the NTSC to submit its petition for FCC approval in July 1953, which was granted on December 17. The first publicly announced network broadcast of a program using the NTSC "compatible color" system was an episode of NBC's Kukla, Fran and Ollie on August 30, 1953, although it was viewable in color only at the network's headquarters.
NBC made the first coast-to-coast color broadcast when it telecast the Tournament of Roses Parade on January 1 1954, with public demonstrations given across the United States on prototype color receivers by manufacturers RCA, General Electric, Philco, Raytheon, Hallicrafters, Hoffman, Pacific Mercury and others. A color model from Westinghouse ($1,295, or $ in today's dollars) became available in the New York area on February 28 and is generally agreed to be the first production receiver using NTSC color offered to the public; a less expensive color model from RCA reached dealers in April. Television's first prime time network color series was The Marriage, a situation comedy broadcast live by NBC in the summer of 1954. NBC's anthology series Ford Theatre became the first color filmed series that October.
Early color telecasts could be preserved only on the black and white kinescope process introduced in 1947. It wasn't until September 1956 that NBC began using color film to time-delay and preserve some of its live color telecasts. Ampex introduced a color videotape recorder in 1958.
Several syndicated shows had episodes filmed in color during the 1950s, including The Cisco Kid, The Lone Ranger, and Adventures of Superman. These were carried by some stations equipped for color telecasts well before NBC began its regular weekly color dramas in 1959, beginning with the Western series Bonanza.
NBC was at the forefront of color programming because its parent company RCA manufactured the most successful line of color sets in the 1950s, and by 1959 RCA was the only remaining major manufacturer of color sets. CBS and ABC, which were not affiliated with set manufacturers, and were not eager to promote their competitor's product, dragged their feet into color. CBS ceased all regular color programming between 1960 and 1965, while ABC delayed its first color series until 1962. The DuMont network, although it did have a television-manufacturing parent company, was in financial decline by 1954 and was dissolved two years later. Thus the relatively small amount of network color programming, combined with the high cost of color television sets, meant that as late as 1964 only 3.1 percent of television households in the U.S. had a color set. NBC provided the catalyst for rapid color expansion by announcing that its prime time schedule for fall 1965 would be almost entirely in color. All three broadcast networks were airing full color prime time schedules by the 1966–67 broadcast season, and ABC aired its last new black and white daytime programming in December 1967. But the number of color television sets sold in the U.S. did not exceed black and white sales until 1972, which was also the first year that more than fifty percent of television households in the U.S. had a color set. This was also the year that "in color" notices before color television programs ended, due to the rise in color television set sales.
Cuba
Cuba in 1958 became the second country in the world to introduce color television broadcasting, with Havana's Channel 12 using the NTSC standard and RCA equipment. But the color transmissions ended when broadcasting stations were seized in the Cuban Revolution in 1959, and did not return until 1975, using equipment acquired from Japan's NEC Corporation, and SECAM equipment from the Soviet Union, adapted for the NTSC standard.
Mexico
In Mexico, Guillermo González Camarena invented an early color television transmission system. He received patents for color television systems in 1942 (U.S. Patent 2,296,019), 1960 and 1962. The 1942 patent (filed in Mexico on August 19, 1940) was for a synchronized color filter wheel adapter for monochrome television, similar to the field sequential color receiver demonstrated by Baird in England in July 1939 and by CBS in the United States in August 1940.
On August 31, 1946 González Camarena sent his first color transmission from his lab in the offices of The Mexican League of Radio Experiments at Lucerna St. #1, in Mexico City. The video signal was transmitted at a frequency of 115 MHz. and the audio in the 40 metre band. He obtained authorization to make the first publicly announced color broadcast in Mexico, on February 8, 1963, of the program Paraíso Infantil on Mexico City's XHGC-TV.
Canada
Color television became available in Canada soon after regular color broadcasting began in the neighboring United States. Canadian stations began their own color broadcasts on September 1, 1966, both in English and in French.
Europe
European color television was developed somewhat later and was hindered by a continuing division on technical standards. Having decided to adopt a higher-definition 625-line system for monochrome transmissions, with a lower frame rate but with a higher overall bandwidth, Europeans could not directly adopt the U.S. color standard. This was widely perceived as inadequate anyway because of its hue error problems, which became particularly acute with the introduction of videotape recorders in the late 1950s. There was also less urgency, since there were fewer commercial motivations, European television broadcasters being predominantly state-owned at the time.
As a consequence, although work on various color encoding systems started already in the 1950s, with the first SECAM patent being registered in 1956, many years had passed when the first broadcasts actually started in 1967. Unsatisfied with the performance of NTSC and of initial SECAM implementations, the Germans unveiled PAL (phase alternating line) in 1963, technically similar to NTSC but borrowing some ideas from SECAM. The French continued with SECAM, notably involving Russians in the development.
The first full-specification PAL receivers ("PAL-D") relied on a precision ultrasonic glass delay line, which in the early days was estimated would make up about a third of the cost of the receiver. Other color encoding systems had already been proposed which would overcome the tint problems of NTSC using such a delay line, but PAL was unique in that an economy receiver (known as "PAL-S" for "simple PAL") could also be built without using a delay line, with a performance no worse than, and in most cases better than an equivalent NTSC model.
SECAM did not require such precision for its delay line, and could use much cheaper magnetostrictive metal types. Ironically, by the time PAL broadcasts commenced in 1967, advances in glassmaking techniques had dropped the cost of precision PAL delay lines so much that hardly any simple-PAL receivers were built commercially, and virtually all SECAM receivers used the same type of delay line as PAL receivers. By the end of the 20th century, glass delay lines had been completely replaced by all-electronic equivalents.
The first regular color broadcasts in Europe were by BBC2 beginning on July 1, 1967 (PAL). West Germany's first broadcast occurred in August (PAL), followed by the French in October (SECAM). Norway, Sweden, Finland, Belgium, The Netherlands, Austria, East Germany, Czechoslovakia, and Hungary all started regular color broadcasts before the end of 1969.
The PAL system spread through most of Western Europe and on into the territories of the old British, Portuguese, Belgian, Dutch, Austro-Hungarian, Ottoman and Chinese Empires.
In Italy there were debates to adopt a national color television system, the ISA, developed by Indesit, but that idea was scrapped. As a result, Italy was one of the last European countries to officially adopt the PAL system in 1977, after long technical experimentation.
France, Luxembourg, and the Soviet Union along with their overseas territories opted for SECAM. SECAM was a popular choice in countries with a lot of hilly terrain, and technologically backward countries with a very large installed base of monochrome equipment, since the greater ruggedness of the SECAM signal could cope much better with poorly maintained equipment.
The only real drawback of SECAM is that, unlike PAL or NTSC, post-production of an encoded SECAM is not really possible without a severe drop in quality.
The first regular color broadcasts in SECAM were started on October 1, 1967, on France's Second Channel (ORTF 2e chaîne).
In France and the UK color broadcasts were made on UHF frequencies, the VHF band being used for legacy black and white, 405 lines in UK or 819 lines in France, till the beginning of the eighties. Countries elsewhere that were already broadcasting 625-line monochrome on VHF and UHF, simply transmitted color programs on the same channels.
It should be noted that some British television programmes, particularly those made by or for ITC Entertainment, were shot on color film before the introduction of color television to the UK, for the purpose of sales to US networks. The first British show to be made in color was the drama series The Adventures of Sir Lancelot (1956-57), which was initially made in black and white but later shot in color for sale to the NBC network in the United States. Other British color television programmes include Stingray (1964-1965), which was the first British TV show to filmed entirely in color, Thunderbirds (1965-1966) and Captain Scarlet (1967-1968).
Asia and the Pacific
Alaska and Hawaii adopted color television after they became U.S. states in 1959. In Japan, NHK introduced color television, using a variation of the NTSC system (called NTSC-J), on September 10, 1960. Other countries in the region did not follow suit until much later, and instead used the PAL system, such as Australia (1967), Hong Kong (1970), Singapore and New Zealand (1973), The Philippines (1976), and Indonesia (1978), with India not introducing it until 1982. South Korea did not introduce color (using NTSC) until 1980, although it was already manufacturing color television sets for export.
Middle East
Nearly all of the countries in the Middle East use PAL, except for Azerbaijan, Armenia, and Georgia which are part of the Commonwealth of Independent States. The first country in the Middle East to introduce color television was Iraq in 1967. The United Arab Emirates, Kuwait, Bahrain, and Qatar followed in the mid-1970s, but Israel, Lebanon and Cyprus continued to broadcast in black and white until the early 1980s.
Africa
The first color television service in Africa was introduced on the Tanzanian island of Zanzibar, in 1973, using PAL. At the time, South Africa did not have a television service at all, owing to opposition from the apartheid regime, but in 1976, one was finally launched. Nigeria adopted PAL for color transmissions in 1974 in the then Benue Plateau state in the north central region of the country, but countries such as Ghana and Zimbabwe continued with black and white until the mid-1980s.
South America
In 1967, Peru became the first South American country to receive color TV, using NTSC. In contrast to most other countries in the Americas, which had adopted NTSC, Brazil began broadcasting in color in PAL-M. Its first transmission was on February 19, 1972. Some countries in South America, including Argentina, Colombia, Uruguay, and Venezuela, continued to broadcast in black and white until the late 1970s.
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