RGB
(Red Green Blue) The computer's native color space, which is the color system for capturing and displaying images. RGB was derived from our own perception of color because human eyes are sensitive to red, green and blue (see trichromaticity).
Capturing
Cameras and scanners capture color with sensors that record the varying intensities of red, green and blue at each pixel location in the frame (see CCD, scanner and digital camera).
Display and Printing (RGB and CMYK)
For screen display, red, green and blue pixels (dots) are energized to the appropriate intensity. When all three pixels are turned on high, white is produced. As intensities are equally lowered, shades are derived. The base color of the screen appears when all pixels are off.
For printing on paper, the CMYK color space is used, not RGB. Combinations of cyan, magenta, yellow and black ink make up all the colors. See CMYK.
Video Processing (RGB or YUV)
TV/video signals are mostly in the YUV color space. They are converted to RGB in the computer for editing when RGB is the desired output. If YUV is the desired output, and the video editing program supports YUV, there is no need to convert to RGB for internal processing. However, no matter which color space is used for editing, all data are converted to RGB for screen display. See YUV and color space.
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| RGB Display and CMYK Printing |
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| Display screens are RGB devices and have red, green and blue pixels. Printers are CMYK devices and use cyan, magenta, yellow and black inks. In theory, equal parts of cyan, magenta and yellow ink make black, but they tend to be muddy. Thus, black ink is used, making it a four color CMYK process (K for blacK). See CMYK. |
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| RGB Color Conversions |
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| Printing requires conversion from RGB to CMYK, and video editing requires conversion to and from RGB and YUV. |
RGB - Red, Green, Blue. The three colours of light which can be
mixed to produce any other colour. Coloured images are often
stored as a sequence of RGB triplets or as separate red, green
and blue overlays though this is not the only possible
representation (see CMYK and HSV). These colours
correspond to the three "guns" in a colour cathode ray tube
and to the colour receptors in the human eye.
Often used as a synonym for colour, as in "RGB monitor" as
opposed to monochrome (black and white). | |