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In computer graphics, pixels encoding the RGBA color space information must be stored in computer memory (or in files on disk). In most cases four equal-sized pieces of adjacent memory are used, one for each channel, and a 0 in a channel indicates black color or transparent alpha, while all-1 bits indicates white or fully opaque alpha.
In some uses, hexadecimal color codes are specified with notation using a leading number sign (#). [1] [2] A color is specified according to the intensity of its red, green and blue components, each represented by eight bits. Thus, there are 24 bits used to specify a web color within the sRGB gamut, and 16,777,216 colors that may be so specified.
Assuming that the pixel color is expressed using straight (non-premultiplied) RGBA tuples, a pixel value of (0, 0.7, 0, 0.5) implies a pixel that has 70% of the maximum green intensity and 50% opacity. If the color were fully green, its RGBA would be (0, 1, 0, 0.5).
On a typical standard 2.2-gamma CRT display, an input intensity RGB value of (0.5, 0.5, 0.5) only outputs about 22% of full brightness (1.0, 1.0, 1.0), instead of 50%. [19] To obtain the correct response, a gamma correction is used in encoding the image data, and possibly further corrections as part of the color calibration process of the device.
The values of Y are in the range from 0 to 1, while Co and Cg are in the range of −0.5 to 0.5, as is typical with "YCC" color models such as YCbCr. For example, pure red is expressed in the RGB system as (1, 0, 0) and in the YCoCg system as ( 1 / 4 , 1 / 2 , − 1 / 4 ).
The color number (0 to 7) can be employed with the following BASIC statements to choose: BORDER n, the color for the surrounding area outside the pixel graphical area. This cannot use the bright variants. PAPER n, the background (pixel bit value of 0) color for an 8×8 pixel cell.
A very simple example can be given between the two colors with RGB values (0, 64, 0) ( ) and (255, 64, 0) ( ): their distance is 255. Going from there to (255, 64, 128) ( ) is a distance of 128. When we wish to calculate distance from the first point to the third point (i.e. changing more than one of the color values), we can do this:
sRGB is a standard numerical encoding of colors, based on the RGB (red, green, blue) color space, for use on monitors, printers, and the World Wide Web.It was initially proposed by HP and Microsoft in 1996 [2] and became an official standard of the International Electrotechnical Commission (IEC) as IEC 61966-2-1:1999. [1]