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==Development== The human eye's detection system in the [[retina]] consists primarily of two types of light detectors: [[rod cell]]s that capture light, dark, and shapes/figures, and the [[cone cell]]s that detect color. A typical retina contains 120 million rods and 4.5 million to 6 million cones, which are divided into three types, each one with a characteristic profile of excitability by different wavelengths of the spectrum of visible light. This means that the eye has far more resolution in brightness, or "[[luminance]]", than in [[color]]. However, post-processing of the optic nerve and other portions of the human visual system combine the information from the rods and cones to re-create what appears to be a high-resolution color image.{{Citation needed|date=July 2024}} The eye has limited bandwidth to the rest of the visual system, estimated at just under 8 Mbit/s.<ref>Michael Reilly, [https://www.newscientist.com/article/dn9633-calculating-the-speed-of-sight "Calculating the speed of sight"] {{webarchive |url=https://web.archive.org/web/20170910114905/https://www.newscientist.com/article/dn9633-calculating-the-speed-of-sight/ |date=10 September 2017}}, ''New Scientist'', 28 July 2006</ref> This manifests itself in a number of ways, but the most important in terms of producing moving images is the way that a series of still images displayed in quick succession will appear to be continuous smooth motion. This illusion starts to work at about 16 [[frame rate|frame/s]], and common motion pictures use 24 frame/s. Television, using power from the [[electrical grid]], historically tuned its rate in order to avoid interference with the [[alternating current]] being supplied – in North America, some Central and South American countries, Taiwan, Korea, part of Japan, the Philippines, and a few other countries, this was 60 [[Field (video)|video fields]] per second to match the 60 Hz power, while in most other countries it was 50 fields per second to match the 50 Hz power. The NTSC color system changed from the [[black-and-white]] 60-fields-per-second standard to 59.94 fields per second to make the color circuitry simpler; the 1950s TV sets had matured enough that the power frequency/field rate mismatch was no longer important. Modern TV sets can display multiple field rates (50, 59.94, or 60, in either interlaced or progressive scan) while accepting power at various frequencies (often the operating range is specified as 48–62 Hz). In its most basic form, a color broadcast can be created by broadcasting three monochrome images, one each in the three colors of [[red]], green, and blue (RGB). When displayed together or in rapid succession, these images will blend together to produce a full-color image as seen by the viewer. To do so without making the images flicker, the refresh time of all three images put together would have to be above the critical limit, and generally the same as a single black and white image. This would require three times the number of images to be sent in the same time, greatly increasing the amount of radio [[bandwidth (signal processing)|bandwidth]] required to send the complete signal and thus similarly increasing the required [[radio spectrum]]. Early plans for color television in the United States included a move from [[very high frequency]] (VHF) to [[ultra high frequency]] (UHF) to open up additional spectrum.{{cn|date=August 2023}} One of the great technical challenges of introducing color [[broadcast television]] was the desire to conserve bandwidth. In the United States, after considerable research, the National Television Systems Committee<ref name=name>National Television System Committee (1951–1953), [Report and Reports of Panel No. 11, 11-A, 12–19, with Some supplementary references cited in the Reports, and the Petition for adoption of transmission standards for color television before the Federal Communications Commission, n.p., 1953], 17 v. illus., diagrams., tables. 28 cm. LC Control No.:54021386 [http://catalog.loc.gov/cgi-bin/Pwebrecon.cgi?DB=local&PAGE=First Library of Congress Online Catalog]</ref> approved an all-electronic system developed by [[RCA]] that encoded the color information separately from the brightness information and greatly reduced the resolution of the color information in order to conserve bandwidth. The brightness image remained compatible with existing black-and-white television sets at slightly reduced resolution, while color-capable televisions could decode the extra information in the signal and produce a limited-resolution color display. The higher resolution black-and-white and lower resolution color images combine in the eye to produce a seemingly high-resolution color image. The [[NTSC]] standard represented a major technical achievement. ===Early television=== Experiments with [[fax|facsimile]] image transmission systems that used radio broadcasts to transmit images date to the 19th century. It was not until the 20th century that advances in electronics and light detectors made television practical. A key problem was the need to convert a 2D image into a "1D" radio signal; some form of image scanning was needed to make this work. Early systems generally used a device known as a "[[Nipkow disk]]", which was a spinning disk with a series of holes punched in it that caused a spot to scan across and down the image. A single photodetector behind the disk captured the image brightness at any given spot, which was converted into a radio signal and broadcast. A similar disk was used at the receiver side, with a light source behind the disk instead of a detector.{{cn|date=August 2023}} A number of such [[mechanical television]] systems were being used experimentally in the 1920s. The best-known was [[John Logie Baird]]'s, which was actually used for regular public broadcasting in Britain for several years. Indeed, Baird's system was demonstrated to members of the Royal Institution in London in 1926 in what is generally recognized as the first demonstration of a true, working television system.<ref>{{Cite web|url=https://www.bbc.co.uk/history/historic_figures/baird_logie.shtml|title=BBC - History - John Logie Baird|language=en-GB|access-date=25 June 2018}}</ref><ref>{{Cite book|title=John Logie Baird: A Life|last1=Kamm|first1=Antony|last2=Baird|first2=John|pages=69}}</ref> In spite of these early successes, all mechanical television systems shared a number of serious problems. Being mechanically driven, perfect synchronization of the sending and receiving discs was not easy to ensure, and irregularities could result in major image distortion. Another problem was that the image was scanned within a small, roughly rectangular area of the disk's surface, so that larger, higher-resolution displays required increasingly unwieldy disks and smaller holes that produced increasingly dim images. Rotating drums bearing small mirrors set at progressively greater angles proved more practical than Nipkow discs for high-resolution mechanical scanning, allowing images of 240 lines and more to be produced, but such delicate, high-precision optical components were not commercially practical for home receivers.{{citation needed|date=March 2011}} It was clear to a number of developers that a completely electronic scanning system would be superior, and that the scanning could be achieved in a vacuum tube via electrostatic or magnetic means. Converting this concept into a usable system took years of development and several independent advances. The two key advances were [[Philo Farnsworth]]'s electronic scanning system, and [[Vladimir Zworykin]]'s [[Iconoscope]] camera. The Iconoscope, based on [[Kálmán Tihanyi]]'s early patents, superseded the Farnsworth-system. With these systems, the [[BBC]] began regularly scheduled black-and-white television broadcasts in 1936, but these were shut down again with the start of [[World War II]] in 1939. In this time thousands of television sets had been sold. The receivers developed for this program, notably those from [[Pye Ltd.]], played a key role in the development of [[radar]]. By 22 March 1935, 180-line black-and-white television programs were being broadcast from the [[Fernsehsender Paul Nipkow|Paul Nipkow TV station]] in [[Berlin]]. In 1936, under the guidance of the Minister of Public Enlightenment and Propaganda, [[Joseph Goebbels]], direct transmissions from fifteen mobile units at the [[1936 Summer Olympics|Olympic Games in Berlin]] were transmitted to selected small television houses ({{lang|de|Fernsehstuben}}) in Berlin and Hamburg. In 1941, the first [[NTSC]] meetings produced a single standard for US broadcasts. US television broadcasts began in earnest in the immediate post-war era, and by 1950 there were 6 million televisions in the United States.<ref>"Television", ''The World Book Encyclopedia'' 2003: 119</ref> ===All-mechanical color=== [[File:Adamian1.jpg|thumb|right|230px|[[Hovannes Adamian]] c. 1900s]] The basic idea of using three monochrome images to produce a color image had been experimented with almost as soon as black-and-white televisions had first been built. 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.<ref>M. Le Blanc, "Etude sur la transmission électrique des impressions lumineuses", ''La Lumière Electrique'', vol. 11, 1 December 1880, pp. 477–481.</ref> 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.<ref>R. W. Burns, ''Television: An International History of the Formative Years'', IET, 1998, p. 98. {{ISBN|0-85296-914-7}}</ref> An [[Armenians|Armenian]] inventor, [[Hovannes Adamian]], also experimented with color television as early as 1907. The first color television project is claimed by him,<ref>Western technology and Soviet economic development: 1945 to 1965, by Antony C. Sutton, Business & Economics - 1973, p. 330</ref> and was patented in [[Germany]] on 31 March 1908, patent number 197183, then in [[United Kingdom|Britain]], on 1 April 1908, patent number 7219,<ref>The History of Television, 1880–1941, by Albert Abramson, 1987, p. 27</ref> in [[France]] (patent number 390326) and in [[Russia]] in 1910 (patent number 17912).<ref name="tvmuseum.ru">{{Cite web|url=http://www.tvmuseum.ru/attach.asp?a_no=1018|archiveurl=https://web.archive.org/web/20130424162531/http://www.tvmuseum.ru/attach.asp?a_no=1018|url-status=usurped|title=A. Rokhlin, Tak rozhdalos' dal'novidenie (in Russian)|archivedate=24 April 2013}}</ref> Shortly after his practical demonstration of black and white television, on 3 July 1928, Baird demonstrated the world's first color transmission. This used 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, controlled by the signal, at the receiving end, with a [[commutator (electric)|commutator]] to alternate their illumination.<ref>John Logie Baird, [https://patents.google.com/patent/US1925554 Television Apparatus and the Like], U.S. patent, filed in U.K. in 1928.</ref> The demonstration was of a young girl wearing different colored hats. The girl, [[Noele Gordon]], later became a TV actress in the soap opera ''[[Crossroads (British TV series)|Crossroads]]''.<ref>As detailed by ITV in their on-air obituary broadcast prior to an episode of ''Crossroads'' broadcast on 14 April 1985</ref><ref>As noted in BBC One's TV Heros series, 1991</ref> Baird also made the world's first color over-the-air broadcast on 4 February 1938, sending a mechanically scanned 120-line image from Baird's [[The Crystal Palace|Crystal Palace]] studios to a projection screen at London's [[Dominion Theatre]].<ref>Baird Television: [https://www.bairdtelevision.com/crystal-palace-television-studios.html Crystal Palace Television Studios], previous color television demonstrations in the U.K. had been via closed circuit.</ref> Mechanically scanned color television was also demonstrated by [[Bell Laboratories]] in June 1929 using three complete systems of [[Solar cell|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. ===Hybrid systems=== {{more citations needed section|date=September 2012}} As was the case with black-and-white television, an electronic means of scanning would be superior to the mechanical systems like Baird's. The obvious solution on the broadcast end would be to use three conventional Iconoscopes with colored filters in front of them to produce an RGB signal. Using three separate tubes each looking at the same scene would produce slight differences in parallax between the frames, so in practice a single lens was used with a mirror or prism system to separate the colors for the separate tubes. Each tube captured a complete frame and the signal was converted into radio in a fashion essentially identical to the existing black-and-white systems. The problem with this approach was there was no simple way to recombine them on the receiver end. If each image was sent at the same time on different frequencies, the images would have to be "stacked" somehow on the display, in real time. The simplest way to do this would be to reverse the system used in the camera: arrange three separate black-and-white displays behind colored filters and then optically combine their images using mirrors or prisms onto a suitable screen, like [[frosted glass]]. [[RCA]] built just such a system in order to present the first electronically scanned color television demonstration on 5 February 1940, privately shown to members of the US Federal Communications Commission at the RCA plant in [[Camden, New Jersey]].<ref>Kenyon Kilbon, ''Pioneering in Electronics: A Short History of the Origins and Growth of RCA Laboratories, Radio Corporation of America, 1919 to 1964'', [http://www.davidsarnoff.org/kil-chapter09.html Chapter Nine – Television: Monochrome to Color] {{webarchive|url=https://web.archive.org/web/20080430082903/http://www.davidsarnoff.org/kil-chapter09.html |date=30 April 2008 }}, 1964. V.K. Zworykin with Frederick Olessi, ''Iconoscope: An Autobiography of Vladimir Zworykin'', [http://www.davidsarnoff.org/vkz-chapter10.html Chapter 10 – Television Becomes a Reality, 1945–1954] {{webarchive|url=https://web.archive.org/web/20080419083408/http://www.davidsarnoff.org/vkz-chapter10.html |date=19 April 2008 }}, 1971. "The system used two color filters in combination with photocells and a flying spot scanner for pickup." Alfred V. Roman, ''The Historical Development of Color Television Systems'', doctoral dissertation, New York University, 1967, p. 49.</ref> This system, however, suffered from the twin problems of costing at least three times as much as a conventional black-and-white set, as well as having very dim pictures, the result of the fairly low illumination given off by tubes of the era. Projection systems of this sort would become common decades later, however, with improvements in technology. Another solution would be to use a single screen, but break it up into a pattern of closely spaced colored phosphors instead of an even coating of white. Three receivers would be used, each sending its output to a separate electron gun, aimed at its colored phosphor. However, this solution was not practical. The [[electron gun]]s used in monochrome televisions had limited resolution, and if one wanted to retain the resolution of existing monochrome displays, the guns would have to focus on individual dots three times smaller. This was beyond the [[state of the art]] of the technology at the time. Instead, a number of hybrid solutions were developed that combined a conventional monochrome display with a colored disk or mirror. In these systems the three colored images were sent one after each other, in either complete frames in the "[[field-sequential color system]]", or for each line in the "line-sequential" system. In both cases a colored filter was rotated in front of the display in sync with the broadcast. Since three separate images were being sent in sequence, if they used existing monochrome radio signaling standards they would have an effective refresh rate of only 20 fields, or 10 frames, a second, well into the region where flicker would become visible. In order to avoid this, these systems increased the frame rate considerably, making the signal incompatible with existing monochrome standards. The first practical example of this sort of system was again pioneered by John Logie Baird. In 1940 he publicly demonstrated a color television combining a traditional black-and-white display with a rotating colored disk. This device was very "deep", but was later improved with a mirror folding the light path into an entirely practical device resembling a large conventional console.<ref>{{cite web|url=http://www.bairdtelevision.com/colour.html|title=The World's First High Definition Colour Television System|website=www.bairdtelevision.com|url-status=live|archive-url=https://web.archive.org/web/20150403170543/http://www.bairdtelevision.com/colour.html|archive-date=3 April 2015}}</ref> However, Baird was not happy with the design, and as early as 1944 had commented to a British government committee that a fully electronic device would be better. In 1939, Hungarian engineer [[Peter Carl Goldmark]] introduced an electro-mechanical system while at [[CBS]], which contained an [[Iconoscope]] sensor. 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.<ref name="Goldmark1">Peter C. Goldmark, assignor to Columbia Broadcasting System, "Color Television", [https://patents.google.com/patent/US2480571 U.S. Patent 2,480,571], filed 7 September 1940.</ref> The system was first demonstrated to the [[Federal Communications Commission]] (FCC) on 29 August 1940, and shown to the press on 4 September.<ref>Current Broadcasting 1940</ref><ref>"Color Television Success in Test", ''[[The New York Times]]'', 30 August 1940, p. 21.</ref><ref>"Color Television Achieves Realism", ''The New York Times'', 5 September 1940, p. 18.</ref><ref>"[https://books.google.com/books?id=JScDAAAAMBAJ&pg=PA120 New Television System Transmits Images in Full Color]", ''Popular Science'', December 1940, p. 120.</ref> CBS began experimental color field tests using film as early as 28 August 1940, and live cameras by 12 November.<ref>"Color Television Success in Test", ''The New York Times'', 30 August 1940, p. 21. "CBS Demonstrates Full Color Television", ''[[The Wall Street Journal]]'', 5 September 1940, p. 1. "Television Hearing Set", ''The New York Times'', 13 November 1940, p. 26.</ref> [[NBC]] (owned by RCA) made its first field test of color television on 20 February 1941. CBS began daily color field tests on 1 June 1941.<ref>Ed Reitan, [http://colortelevision.info/rca-nbc_firsts.html RCA-NBC Color Firsts in Television (commented)] {{webarchive |url=http://archive.wikiwix.com/cache/20141225155750/http://colortelevision.info/rca-nbc_firsts.html |date=25 December 2014}}</ref> 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, viewing of the color field tests was restricted 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 22 April 1942, to 20 August 1945, limiting any opportunity to introduce color television to the general public.<ref>"Making of Radios and Phonographs to End April 22", ''The New York Times'', 8 March 1942, p. 1. "Radio Production Curbs Cover All Combinations", ''The Wall Street Journal'', 3 June 1942, p. 4. "WPB Cancels 210 Controls; Radios, Trucks in Full Output", ''The New York Times'', 21 August 1945, p. 1.</ref><ref>Bob Cooper, "[http://www.earlytelevision.org/color_tv_cooper.html Television: The Technology That Changed Our Lives] {{webarchive |url=https://web.archive.org/web/20141223155937/http://www.earlytelevision.org/color_tv_cooper.html |date=December 23, 2014}}", Early Television Foundation.</ref> ===Fully electronic=== [[File:Baird first color photo.jpg|thumb|right|This live image of actress [[Paddy Naismith]] was used to demonstrate [[Telechrome]], [[John Logie Baird]]'s first all-electronic color television system, which used two projection CRTs. The two-color image would be similar to the basic Telechrome system.]] As early as 1940, Baird had started work on a fully electronic system he called the "[[Telechrome]]". Early Telechrome devices used two electron guns aimed at either side of a phosphor plate. The phosphor was patterned so the electrons from the guns only fell on one side of the patterning or the other. Using cyan and magenta phosphors, a reasonable limited-color image could be obtained. Baird's demonstration on 16 August 1944, was the first example of a practical color television system.<ref>{{cite book|last1=Hempstead|first1=Colin|title=Encyclopedia of 20th-Century Technology|url=https://archive.org/details/encyclopediathce00hemp|url-access=limited|date=2005|publisher=Routledge|page=[https://archive.org/details/encyclopediathce00hemp/page/n873 824]}}</ref> Work on the Telechrome continued and plans were made to introduce a three-gun version for full color. However, Baird's untimely death in 1946 ended the development of the Telechrome system.<ref>Albert Abramson, ''The History of Television, 1942 to 2000'', McFarland & Company, 2003, pp. 13–14. {{ISBN|0-7864-1220-8}}</ref><ref>Baird Television: [http://www.bairdtelevision.com/colour.html The World's First High Definition Colour Television System] {{webarchive|url=https://web.archive.org/web/20150403170543/http://www.bairdtelevision.com/colour.html |date=3 April 2015 }}</ref> Similar concepts were common through the 1940s and 1950s, differing primarily in the way they re-combined the colors generated by the three guns. The [[Geer tube]] was similar to Baird's concept, but used small pyramids with the phosphors deposited on their outside faces, instead of Baird's 3D patterning on a flat surface. The [[Penetron]] used three layers of phosphor on top of each other and increased the power of the beam to reach the upper layers when drawing those colors. The [[Chromatron]] used a set of focusing wires to select the colored phosphors arranged in vertical stripes on the tube. ====FCC color==== In the immediate post-war era, the [[Federal Communications Commission]] (FCC) was inundated with requests to set up new television stations. Worrying about congestion of the limited number of channels available, the FCC put a moratorium on all new licenses in 1948 while considering the problem. A solution was immediately forthcoming; rapid development of radio receiver electronics during the war had opened a wide band of higher frequencies to practical use, and the FCC set aside a large section of these new [[Ultra high frequency|UHF]] bands for television broadcast. At the time, black-and-white television broadcasting was still in its infancy in the U.S., and the FCC started to look at ways of using this newly available bandwidth for color broadcasts. Since no existing television would be able to tune in these stations, they were free to pick an incompatible system and allow the older [[Very high frequency|VHF]] channels to die off over time. The FCC called for technical demonstrations of color systems in 1948, and the Joint Technical Advisory Committee (JTAC) was formed to study them. CBS displayed improved versions of its original design, now using a single 6 MHz channel (like the existing black-and-white signals) at 144 fields per second and 405 lines of resolution. [[Color Television Inc.|Color Television Inc. (CTI)]] demonstrated its line-sequential system, while [[Philco]] demonstrated a dot-sequential system based on its [[beam-index tube]]-based "Apple" tube technology. Of the entrants, the CBS system was by far the best-developed, and won head-to-head testing every time. While the meetings were taking place it was widely known within the industry that RCA was working on a dot-sequential system that was compatible with existing black-and-white broadcasts, but RCA declined to demonstrate it during the first series of meetings. Just before the JTAC presented its findings, on 25 August 1949, RCA broke its silence and introduced its system as well. The JTAC still recommended the CBS system, and after the resolution of an ensuing RCA lawsuit, color broadcasts using the CBS system started on 25 June 1951. By this point the market had changed dramatically; when color was first being considered in 1948 there were fewer than a million television sets in the U.S., but by 1951 there were well over 10 million. The idea that the VHF band could be allowed to "die" was no longer practical. During its campaign for FCC approval, CBS gave the first demonstrations of color television to the general public, showing an hour of color programs daily Mondays through Saturdays, beginning 12 January 1950, and running for the remainder of the month, over [[WUSA (TV)|WOIC]] in Washington, D.C., where the programs could be viewed on eight 16-inch color receivers in a public building.<ref>"Washington Chosen for First Color Showing; From Ages 4 to 90, Audience Amazed", ''[[The Washington Post]]'', 13 January 1950, p. B2.</ref> Due to high public demand, the broadcasts were resumed 13–21 February, with several evening programs added.<ref>"Color TV Tests To Be Resumed In Washington", ''The Washington Post'', 12 February 1950, p. M5.</ref> CBS initiated a limited schedule of color broadcasts from its New York station [[WCBS-TV]] Mondays to Saturdays beginning 14 November 1950, making ten color receivers available for the viewing public.<ref>"CBS Color Television To Make Public Debut In N.Y. Next Week", ''The Wall Street Journal'', 9 November 1950, p. 18.</ref><ref>[http://www.earlytelevision.org/images/TV0441-150dpi.jpg CBS Announces Color Television] {{webarchive |url=https://web.archive.org/web/20080804175847/http://www.earlytelevision.org/images/TV0441-150dpi.jpg |date=4 August 2008}} (advertisement), New York ''Daily News'', 13 November 1950.</ref> All were broadcast using the single color camera that CBS owned.<ref>"You Can See The Blood on Color Video", ''The Washington Post'', 15 January 1950, p. L1. "Video Color Test Begins on C.B.S.", ''The New York Times'', 14 November 1950, p. 44.</ref> The New York broadcasts were extended by [[coaxial cable]] to Philadelphia's [[WCAU|WCAU-TV]] beginning 13 December,<ref>"CBS Color Preview Seen By 2,000 in Philadelphia", ''The Wall Street Journal'', 16 December 1950, p. 10.</ref> and to Chicago on 10 January,<ref>"CBS to Display Color Video in City Next Week", ''Chicago Tribune'', 6 January 1951, television and radio section, p. C4.</ref><ref>"Preview of CBS Color TV Wins City's Acclaim", ''Chicago Tribune'', 10 January 1951, p. A8.</ref> making them the first network color broadcasts. 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 11 October 1950. An unsuccessful lawsuit by RCA delayed the first commercial network broadcast in color until 25 June 1951, when a musical variety special titled simply [[Premiere (TV program)|''Premiere'']] was shown over a network of five East Coast CBS affiliates.<ref>"C.B.S. Color Video Presents a 'First'", ''The New York Times'', 26 June 1951, p. 31.</ref> Viewing was again restricted: the program could not be seen on black-and-white sets, and ''[[Variety (magazine)|Variety]]'' estimated that only thirty prototype color receivers were available in the New York area.<ref>Four-hundred guests watched the premiere commercial broadcast on eight color receivers at a CBS studio in New York, as no color receivers were available to the general public. "C.B.S. Color Video Presents a 'First'", ''The New York Times'', 26 June 1951, p. 31. A total of about 40 color receivers was available in the five cities on the color network. The CBS affiliate in Washington had three receivers and a monitor. "First Sponsored TV in Color Praised by WTOP Audience", ''The Washington Post'', 26 June 1951, p. 1. Most of the remainder of the prototype color receivers were given to advertisers sponsoring the color broadcasts. "Today, June 25, 1951, is a turning point in broadcasting history" (WTOP-TV advertisement), ''The Washington Post'', 25 June 1951, p. 10.</ref> Regular color broadcasts began that same week with the daytime series ''[[The World Is Yours (TV 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),<ref>Ed Reitan, "[https://web.archive.org/web/20061206003312/http://www.novia.net/~ereitan/CBS_Color_Programming_rev_h.htm#ProgressColorcasting Progress of CBS Colorcasting]", ''Programming for the CBS Color System''.</ref> and the color network expanded to eleven affiliates as far west as Chicago,<ref>"[https://web.archive.org/web/20061206003312/http://www.novia.net/~ereitan/CBS_Color_Programming_rev_h.htm#affiliates CBS Color System Network Affiliates]", ''Programming for the CBS Color System''.</ref> 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,<ref>"CBS Color System Makes Television Set Makers See Red", ''The Wall Street Journal'', 17 October 1950, p. 1. Three exceptions among the major television manufacturers were [[Philco]], which offered 11 models that could show CBS color broadcasts in black-and-white; and [[Westinghouse Electric Corporation (1886)|Westinghouse]] and [[Admiral (electrical appliances)|Admiral]], which offered adapters to receive color broadcasts in black and white. "Philco Offers 11 TV Sets To Receive CBS Color TV in Black and White", ''The Wall Street Journal'', 4 June 1951, p. 9. "Westinghouse to Sell Adapter for CBS Color TV Signals", ''The Wall Street Journal'', 7 August 1951, p. 18.</ref> and the unwillingness of advertisers to sponsor broadcasts seen by almost no one. CBS had bought a television manufacturer in April,<ref>"Hytron's Deal With CBS Seen TV Color Aid", ''The Washington Post'', 12 April 1951, p. 15.</ref> and in September 1951, production began on the only CBS-Columbia color television model, with the first color sets reaching retail stores on 28 September.<ref>"CBS Subsidiary Starts Mass Production of Color Television Sets", ''The Wall Street Journal'', 13 September 1951, p. 18.</ref><ref>"[https://books.google.com/books?id=oCEEAAAAMBAJ&pg=PA8 Para-TV Color Sets To Go On Sale Soon]", ''[[Billboard (magazine)|Billboard]]'', 6 October 1951, p. 6.</ref> However, it was too little, too late. Only 200 sets had been shipped, and only 100 sold, when CBS discontinued its color television system on 20 October 1951, ostensibly by request of the [[National Production Authority]] for the duration of the [[Korean War]], and bought back all the CBS color sets it could to prevent lawsuits by disappointed customers.<ref>"[https://books.google.com/books?id=pCEEAAAAMBAJ&q=cbs+color Text of Note to CBS Asking Color Set Halt]", ''Billboard'', 27 October 1951, p. 5</ref><ref>"Color TV Shelved As a Defense Step", ''The New York Times'', 20 October 1951, p. 1. "Action of Defense Mobilizer in Postponing Color TV Poses Many Question for the Industry", ''The New York Times'', 22 October 1951, p. 23. Ed Reitan, [http://novia.net/~ereitan/Color_Sys_CBS.html CBS Field Sequential Color System] {{webarchive |url=https://web.archive.org/web/20100105183213/http://novia.net/~ereitan/Color_Sys_CBS.html |date=5 January 2010}}, 1997</ref> RCA chairman [[David Sarnoff]] later charged that the NPA's order had come "out of a situation artificially created by one company to solve its own perplexing problems" because CBS had been unsuccessful in its color venture. ====Compatible color==== <!-- Courtesy note per [[WP:RSECT]]: [[Compatible color]] and [[Color compatible]] redirect here --> While the FCC was holding its JTAC meetings, development was taking place on a number of systems allowing true simultaneous color broadcasts, "dot-sequential color systems". Unlike the hybrid systems, dot-sequential televisions used a signal very similar to existing black-and-white broadcasts, with the intensity of every dot on the screen being sent in succession. In 1938 [[Georges Valensi]] demonstrated an encoding scheme that would allow color broadcasts to be encoded so they could be picked up on existing black-and-white sets as well. In his system the output of the three camera tubes were re-combined to produce a single "[[Luma (video)|luminance]]" value that was very similar to a monochrome signal and could be broadcast on the existing VHF frequencies. The color information was encoded in a separate "[[chrominance]]" signal, consisting of two separate signals, the original blue signal minus the luminance (B'–Y'), and red-luma (R'–Y'). These signals could then be broadcast separately on a different frequency; a monochrome set would tune in only the luminance signal on the VHF band, while color televisions would tune in both the luminance and chrominance on two different frequencies, and apply the reverse transforms to retrieve the original RGB signal. The downside to this approach is that it required a major boost in bandwidth use, something the FCC was interested in avoiding. RCA used Valensi's concept as the basis of all of its developments, believing it to be the only proper solution to the broadcast problem. However, RCA's early sets using mirrors and other projection systems all suffered from image and color quality problems, and were easily bested by CBS's hybrid system. But solutions to these problems were in the pipeline, and RCA in particular was investing massive sums (later estimated at $100 million) to develop a usable dot-sequential tube. RCA was beaten to the punch by the [[Geer tube]], which used three B&W tubes aimed at different faces of colored pyramids to produce a color image. All-electronic systems included the [[Chromatron]], [[Penetron]] and [[beam-index tube]] that were being developed by various companies. While investigating all of these, RCA's teams quickly started focusing on the [[shadow mask]] system. In July 1938 the [[shadow mask]] color television was patented by [[Werner Flechsig]] (1900–1981) in Germany, and was demonstrated at the [[IFA Berlin|International radio exhibition Berlin]] in 1939. Most CRT color televisions used today are based on this technology. His solution to the problem of focusing the electron guns on the tiny colored dots was one of brute-force; a metal sheet with holes punched in it allowed the beams to reach the screen only when they were properly aligned over the dots. Three separate guns were aimed at the holes from slightly different angles, and when their beams passed through the holes the angles caused them to separate again and hit the individual spots a short distance away on the back of the screen. The downside to this approach was that the mask cut off the vast majority of the beam energy, allowing it to hit the screen only 15% of the time, requiring a massive increase in beam power to produce acceptable image brightness. The first publicly announced network demonstration of a program using a "compatible color" system was an episode of NBC's [[Kukla, Fran and Ollie]] on 10 October 1949,<ref>[https://www.youtube.com/watch?v=wmBKjL00BSA "Kukla, Fran and Ollie" broadcast]</ref> viewable in color only at the FCC. It did not receive FCC approval. In spite of these problems in both the broadcast and display systems, RCA pressed ahead with development and was ready for a second assault on the standards by 1950. ====Second NTSC==== The possibility of a compatible color broadcast system was so compelling that the NTSC decided to re-form, and held a second series of meetings starting in January 1950. Having only recently selected the CBS system, the FCC heavily opposed the NTSC's efforts. One of the FCC Commissioners, R. F. Jones, went so far as to assert that the engineers testifying in favor of a compatible system were "in a conspiracy against the public interest". Unlike the FCC approach where a standard was simply selected from the existing candidates, the NTSC would produce a board that was considerably more pro-active in development. Starting before CBS color even got on the air, the U.S. television industry, represented by the [[NTSC|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 [[WNBC|WNBT]] in July 1951.<ref>"RCA to Test Color TV System On Three Shows Daily Beginning Today", ''The Wall Street Journal'', 9 July 1951, p. 3.</ref> When CBS testified before Congress in March 1953 that it had no further plans for its own color system,<ref>"CBS Says Confusion Now Bars Color TV", ''The Washington Post'', 26 March 1953, p. 39.</ref> the [[National Production Authority]] dropped its ban on the manufacture of color television receivers,<ref>"N.P.A. Decides to End Restrictions on Output Of Color TV Sets", ''The Wall Street Journal'', 21 March 1953, p. 1.</ref> and the path was open for the NTSC to submit its petition for FCC approval in July 1953, which was granted on 17 December.<ref>"F.C.C. Rules Color TV Can Go on Air at Once", ''The New York Times'', 19 December 1953, p. 1.</ref> The first publicly announced network demonstration of a program using the NTSC "compatible color" system was an episode of NBC's ''[[Kukla, Fran and Ollie]]'' on 30 August 1953, although it was viewable in color only at the network's headquarters. The first network broadcast to go out over the air in NTSC color was a performance of the opera ''[[Carmen]]'' on 31 October 1953.
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