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Bubbles The Clown
Test Card F is a test card that was created by the BBC and used on television in the United Kingdom and in countries elsewhere in the world for more than four decades. Like other test cards, it was usually shown while no programmes were being broadcast. It was the first to be transmitted in colour in the UK and the first to feature a person, and has become an iconic British image regularly subject to parody. The central image on the card shows Carole Hersee playing noughts and crosses with a clown doll, Bubbles the Clown, surrounded by various grayscale, greyscales and colour test signals used to assess the quality of the transmitted picture. It was first broadcast on 2 July 1967 (the day after the first colour pictures appeared to the public on television) on BBC Two, BBC2. The card was developed by BBC Broadcast engineering, engineer George Hersee (1924–2001), the father of the girl in the central image. It was frequently broadcast during daytime downtime on BBC Television ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Testcard F
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 (often at sign-on and sign-off). Used since the earliest TV broadcasts, test cards were originally physical cards at which a television camera was pointed, allowing for simple adjustments of picture quality. Such cards are still often used for calibration, alignment, and matching of cameras and camcorders. From the 1950s, test card images were built into monoscope tubes which freed up the use of TV cameras which would otherwise have to be rotated to continuously broadcast physical test cards during downtime hours. Electronically generated test patterns, used for calibrating or troubleshooting the downstream signal path, were introduced in the late-1960s, and became commonly used from the 1970s and 80s. These are generated by test signal generators, which do not depend on the correct config ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BBC HD
BBC HD was a high-definition television channel owned by the BBC. The channel was initially run as a trial from 15 May 2006 until becoming a full service on 1 December 2007 before its discontinuation on 25 March 2013. It broadcast only during the afternoon and evening and only broadcast material shot in high definition, either in a simulcast with another channel or by inserting a repeat of an HD programme. The channel featured a mix of programming including new episodes of '' Top Gear'', ''Doctor Who'' and '' Hustle'', repeats of HD programmes including '' Planet Earth'', ''Bleak House'' and '' Torchwood'' as well as live coverage of large events such as The Proms, Wimbledon, the Eurovision Song Contest and the FIFA World Cup. The channel closed for the final time at 01:20 am on the night of Monday 25 March 2013, and was replaced with BBC Two HD the following day on Tuesday 26 March, partly as a result of budget cuts affecting the entire corporation. History Trial BBC H ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Noughts-and-crosses
Tic-tac-toe (American English), noughts and crosses (English in the Commonwealth of Nations, Commonwealth English), or Xs and Os (Canadian English, Canadian or Hiberno-English, Irish English) is a paper-and-pencil game for two players who take turns marking the spaces in a three-by-three grid, one with Xs and the other with Os. A player wins when they mark all three spaces of a row, column, or diagonal of the grid, whereupon they traditionally draw a line through those three marks to indicate the win. It is a solved game, with a forced draw assuming Best response, best play from both players. Names In American English, the game is known as "tic-tac-toe". It may also be spelled "tick-tack-toe", "tick-tat-toe", or "tit-tat-toe". In Commonwealth English (particularly British English, British, South African English, South African, Indian English, Indian, Australian English, Australian, and New Zealand English), the game is known as "noughts and crosses", alternatively spelled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frequency Response
In signal processing and electronics, the frequency response of a system is the quantitative measure of the magnitude and Phase (waves), phase of the output as a function of input frequency. The frequency response is widely used in the design and analysis of systems, such as audio system, audio and control systems, where they simplify mathematical analysis by converting governing differential equations into algebraic equations. In an audio system, it may be used to minimize audible distortion by designing components (such as microphones, Audio power amplifier, amplifiers and loudspeakers) so that the overall response is as flat (uniform) as possible across the system's Bandwidth (signal processing), bandwidth. In control systems, such as a vehicle's cruise control, it may be used to assess system Stability theory, stability, often through the use of Bode plots. Systems with a specific frequency response can be designed using analog filter, analog and digital filters. The frequency ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Overscan
Overscan is a behaviour in certain television sets in which part of the input picture is cut off by the visible bounds of the screen. It exists because cathode-ray tube (CRT) television sets from the 1930s to the early 2000s were highly variable in how the video image was positioned within the borders of the screen. It then became common practice to have video signals with black edges around the picture, which the television was meant to discard in this way. Origins Early analog televisions varied in the displayed image because of manufacturing tolerance problems. There were also effects from the early design limitations of power supplies, whose DC voltage was not regulated as well as in later power supplies. This could cause the image size to change with normal variations in the AC line voltage, as well as a process called blooming, where the image size increased slightly when a brighter overall picture was displayed due to the increased electron beam current causing the CRT anod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black
Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''Psychologie de la couleur – effets et symboliques'', pp. 105–26. Black and white have often been used to describe opposites such as good and evil, the Dark Ages versus the Age of Enlightenment, and night versus day. Since the Middle Ages, black has been the symbolic color of solemnity and authority, and for this reason it is still commonly worn by judges and magistrates. Black was one of the first colors used by artists in Neolithic cave paintings. It was used in ancient Egypt and Greece as the color of the underworld. In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches, and magic. In the 14th century, it was worn by royalty, clergy, judges, and governm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue
Blue is one of the three primary colours in the RYB color model, RYB colour model (traditional colour theory), as well as in the RGB color model, RGB (additive) colour model. It lies between Violet (color), violet and cyan on the optical spectrum, spectrum of visible light. The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; Azure (color), azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering#Cause of the blue colour of the sky, Rayleigh scattering. An optical effect called the Tyndall effect explains Eye color#Blue, blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Magenta
Magenta () is a purple-red color. On color wheels of the RGB color model, RGB (additive) and subtractive color, CMY (subtractive) color models, it is located precisely midway between blue and red. It is one of the four colors of ink used in color printing by most Color printing, color printers, along with yellow, cyan, and black to make all the other colors. Magenta is a color made by mixing red and blue. The tone of magenta used in printing, Shades of magenta, printer's magenta, is redder than the magenta of the RGB (additive) model, the former being closer to Rose (color), rose. Magenta took its name from an aniline dye made and patented in 1859 by the French chemist François-Emmanuel Verguin, who originally called it ''fuchsine''. It was renamed to celebrate the French-Sardinian victory under French Emperor Napoleon III at the Battle of Magenta against the larger army of the Austrian Empire on 4 June 1859 near the Italian town of Magenta, Lombardy, Magenta, at the time in Au ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Green
Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 nm. In subtractive color systems, used in painting and color printing, it is created by a combination of yellow and cyan; in the RGB color model, used on television and computer screens, it is one of the additive primary colors, along with red and blue, which are mixed in different combinations to create all other colors. By far the largest contributor to green in nature is chlorophyll, the chemical by which plants photosynthesize and convert sunlight into chemical energy. Many creatures have adapted to their green environments by taking on a green hue themselves as camouflage. Several minerals have a green color, including the emerald, which is colored green by its chromium content. During post-classical and early modern Europe, green was the color commonly associated with wealth, merchants, bankers, and the gentry, whil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyan
Cyan () is the color between blue and green on the visible spectrum of light. It is evoked by light with a predominant wavelength between 500 and 520 nm, between the wavelengths of green and blue. In the subtractive color system, or CMYK color model, which can be overlaid to produce all colors in paint and color printing, cyan is one of the primary colors, along with magenta and yellow. In the additive color system, or RGB color model, used to create all the colors on a computer or television display, cyan is made by mixing equal amounts of green and blue light. Cyan is the complement of red; it can be made by the removal of red from white. Mixing red light and cyan light at the right intensity will make white light. It is commonly seen on a bright, sunny day in the sky. Shades and variations Different shades of cyan can vary in terms of hue, chroma (also known as saturation, intensity, or colorfulness), or lightness (or value, tone, or brightness), or any combinat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yellow
Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the RGB color model, used to create colors on television and computer screens, yellow is a secondary color made by combining red and green at equal intensity. Carotenoids give the characteristic yellow color to autumn leaves, corn, canaries, daffodils, and lemons, as well as egg yolks, buttercups, and bananas. They absorb light energy and protect plants from photo damage in some cases. Sunlight has a slight yellowish hue when the Sun is near the horizon, due to atmospheric scattering of shorter wavelengths (green, blue, and violet). Because it was widely available, yellow ochre pigment was one of the first colors used in art; the Lascaux cave in France has a painting of a yellow horse 17,000 years old. Ochre and orpiment pigmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
White
White is the lightest color and is achromatic (having no chroma). It is the color of objects such as snow, chalk, and milk, and is the opposite of black. White objects fully (or almost fully) reflect and scatter all the visible wavelengths of light. White on television and computer screens is created by a mixture of red, blue, and green light. The color white can be given with white pigments, especially titanium dioxide. In ancient Egypt and ancient Rome, priestesses wore white as a symbol of purity, and Romans wore white togas as symbols of citizenship. In the Middle Ages and Renaissance a white unicorn symbolized chastity, and a white lamb sacrifice and purity. It was the royal color of the kings of France as well as the flag of monarchist France from 1815 to 1830, and of the monarchist movement that opposed the Bolsheviks during the Russian Civil War (1917–1922). Greek temples and Roman temples were faced with white marble, and beginning in the 18t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
