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Color television is a television transmission technology that includes information on the color of the picture, so the video image can be displayed in color on the television screen. It is an improvement on the earliest television technology, monochrome or black and white television, in which the image is displayed in shades of grey (greyscale). Television broadcasting stations and networks in most parts of the world upgraded from black and white to color transmission in the 1960s and 1970s, and today virtually all television besides some inexpensive closed-circuit surveillance video systems is color television, so the term is becoming redundant and is not used much. The invention of color television standards is part of the history of television, and is described in the technology of television. 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. One of the great technical challenges of introducing color broadcast television was the desire to conserve bandwidth, potentially three times that of the existing black-and-white standards, and not use an excessive amount of radio spectrum. In the United States, after considerable research, the National Television Systems Committee〔National Television System Committee (1951–1953), (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 (Library of Congress Online Catalog )〕 approved an all-electronic system developed by RCA which 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 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. Although all-electronic color was introduced in the U.S. in 1953, high prices and the scarcity of color programming greatly slowed its acceptance in the marketplace. The first national color broadcast (the 1954 Tournament of Roses Parade) occurred on January 1, 1954, but during the next ten years most network broadcasts, and nearly all local programming, continued to be in black-and-white. Singing sensation Patti Page and her Big Record Show for CBS was the first television show broadcast in color for the entire 1957-1958 season. The live broadcast was staged in the now famous Ed Sullivan Theatre and production costs were greater than most movies were at the time not only because of all the stars featured on the hour-long extravaganza but the extreme high intensity lighting and electronics required for the new RCA TK-41 cameras. It was not until the mid-1960s that color sets started selling in large numbers, due in part to the color transition of 1965 in which it was announced that over half of all network prime-time programming would be broadcast in color that fall. The first all-color prime-time season came just one year later. Early color sets were either floor-standing console models or tabletop versions nearly as bulky and heavy, so in practice they remained firmly anchored in one place. The introduction of GE's relatively compact and lightweight Porta-Color set in the spring of 1966 made watching color television a more flexible and convenient proposition. In 1972, sales of color sets finally surpassed sales of black-and-white sets. Also in 1972, the last holdout among daytime network programs converted to color, resulting in the first completely all-color network season. Color broadcasting in Europe was not standardized on the PAL format until the 1960s, and broadcasts did not start until 1967. By this point many of the technical problems in the early sets had been worked out, and the spread of color sets in Europe was fairly rapid. By the mid-1970s, the only stations broadcasting in black-and-white were a few high-numbered UHF stations in small markets, and a handful of low-power repeater stations in even smaller markets such as vacation spots. By 1979, even the last of these had converted to color and by the early 1980s B&W sets had been pushed into niche markets, notably low-power uses, small portable sets, or use as video monitor screens in lower-cost consumer equipment. By the late 1980s even these areas switched to color sets. ==Development== The human eye's detection system in the retina consists primarily of two types of light detectors, rod cells that capture light, dark, and shapes/figures, and the cone cells that detect color. A typical retina contains 120 million rods and 4.5 million to 6 million cones, which are divided among three groups that are sensitive to red, green, and blue light. This means that the eye has far more resolution in brightness, or "luminance", than in color. However, post-processing in 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. The eye has limited bandwidth to the rest of the visual system, estimated at just under 8 Mbit/s.〔Michael Reilly, ("Calculating the speed of sight" ), ''New Scientist'', July 28, 2006〕 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/s, and common motion pictures use 24 frame/s. Television, using power from the electrical grid, tunes 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 is 60 video fields per second to match the 60 Hz power, while in most other countries it is 50 fields per second to match the 50 Hz power. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Color television」の詳細全文を読む スポンサード リンク
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