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CSS also supports the special color transparent, which represents an alpha value of zero; by default, transparent is rendered as an invisible nominal black: rgba(0, 0, 0, 0). It was introduced in CSS1 but its scope of use has expanded over the versions.
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.
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.
In the infobox, the coordinates are presented as three numbers separated by commas, as in this example for the color orange: (255, 165, 0) The coordinates within the parenthesis provide, in order, the relative values of red, green, and blue light. The number in each position ranges from 0 (no color added) to 255 (100% color added).
L for perceptual lightness, ranging from 0 (pure black) to 1 (reference white, if achromatic), often denoted as a percentage; a and b for opponent channels of the four unique hues, unbounded but in practice ranging from −0.5 to +0.5; CSS assigns ±100% to ±0.4 for both [2] a for green (negative) to red (positive) b for blue (negative) to ...
Download QR code; Print/export Download as PDF; ... 0 0 15 px rgba (0, 0, 0, 0.5);} ... 16 px; margin: 4 px 2 px; transition: background-color 0.3 s ease, transform 0 ...
Example of U-V color plane, Y′ value = 0.5, represented within RGB color gamut An image along with its Y′, U, and V components respectively. Y′UV, also written YUV, is the color model found in the PAL analogue color TV standard. A color is described as a Y′ component and two chroma components U and V.