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YUV signals are created from an original RGB ( red, green and blue) source. The weighted values of R, G and B are added together to produce a single Y signal, representing the overall brightness, or luminance, of that spot. The U signal is then created by subtracting the Y from the blue signal of the original RGB, and then scaling; and V by subtracting the Y from the red, and then scaling by a different factor. This can be accomplished easily with analog circuitry.
The following equations can be used to derive Y, U and V from R, G and B:
Y = + 0.299R + 0.587G + 0.114B U = + 0.492(B - Y) = - 0.147R - 0.289G + 0.436B V = + 0.877(R - Y) = + 0.615R - 0.515G - 0.100BHere, R, G and B are assumed to range from 0 to 1, with 0 representing the minimum intensity and 1 the maximum.
The primary advantage of luminance/chrominance systems such as YUV and its relatives YIQ and YDbDrYDbDr is the colour space used in the SECAM colour television broadcasting standard, which is used in France and some countries of the former Eastern Bloc. Y is the luminance, and Db and Dr are the red and blue colour differences. These are related to the is that they remain compatible (thanks to Georges ValensiGeorges Valensi was a French telecommunications engineer who in 1938 invented and patented a method that allows color images to be transmitted and received on both color and black and white television sets. Rival color television methods, which had been i) with black and white analog televisionAnalog television represents different image brightness levels by different voltages. It is used in distinction to digital television. All early television standards were analog in nature, and digital television systems derive much of their structure from. The Y signal is essentially the same signal that would be broadcast from a normal black and white camera (with some subtle changes), and the U and V signals can simply be ignored. When used in a color setting the subtraction process is reversed, resulting in the original RGB color space.
Another advantage is that the signal in YUV can be easily manipulated to deliberately discard some information in order to reduce bandwidthAnalog Bandwidth is the width, usually measured in hertz, of a frequency band f f. It can also be used to describe a signal, in which case the meaning is the width of the smallest frequency band within which the signal can fit. It is usually notated B, W,. The human eye actually has fairly low color resolution: the high-resolution color images we see are processed by the visual system by combining the high-resolution black and white image with the low-resolution color image. Using this information to their advantage, standards such as NTSC reduce the amount of signal in the chrominance considerably, leaving the eye to recombine them. For instance, NTSC saves only 11% of the original blue and 30% of the original red, throwing out the rest. Since the green is already encoded in the Y signal, the resulting U and V signals are substantially smaller than they would otherwise be if the original RGB or YUV signals were sent. This filtering out of the blue and red signals is trivial to accomplish once the signal is in YUV format.
However this process, obviously, reduces the quality of the image. In the 1950sCenturies: 19th century 20th century 21st century Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s 2000s Years: 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 Events and trends Technology United States tests the first fusion bomb. when NTSC was being created this was not a real concern because common equipment could not display images any better than the quality of the signal they were already receiving. But today a modern television can display more information than is contained in these lossy signals. This has led to a number of attempts to record images with as much of the YUV signal as possible, including S-VideoS-Video (also known as Y/C is a baseband analog video format offering a higher quality signal than composite video, but a lower quality than RGB and component video. This mid-level format divides the signal into two channels luminance and chrominance. on VCRs. YUV was also used as the standard format for common video compression algorithms such as MPEG-2, which is used in digital television and for DVDs. The professional CCIR 601 uncompressed digital video format also uses the YUV colour space, for compatibility with previous analog video formats, which can then be easily mixed into any output format needed.
YUV is a versatile format which can be easily combined into other legacy video formats. For instance if you amplitude-modulate the U and V signals onto quadrature phases of a subcarrier you end up with a single signal called C, for chroma, which can then make the YC signal that is S-Video. If you mix the Y and C signals, you end up with composite video, which almost any television can handle. All of this modulating can be accomplished easily in low-cost circuitry, while the demodulation is often very difficult indeed. Leaving the signal in the original YUV format thus made DVDs very simple to construct, as they could easily downmix to support either S-video or composite and thus guarantee compability with simple circuits, while still retaining all of the original information from the source RGB signal.
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