bits per pixel


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bits per pixel

(hardware, graphics)
(bpp) The number of bits of information stored per pixel of an image or displayed by a graphics adapter. The more bits there are, the more colours can be represented, but the more memory is required to store or display the image.

A colour can be described by the intensities of red, green and blue (RGB) components. Allowing 8 bits (1 byte) per component (24 bits per pixel) gives 256 levels for each component and over 16 million different colours - more than the human eye can distinguish. Microsoft Windows alls this truecolour. An image of 1024x768 with 24 bpp requires over 2 MB of memory.

"High colour" uses 16 bpp (or 15 bpp), 5 bits for blue, 5 bits for red and 6 bits for green. This reduced colour precision gives a slight loss of image quality at a 1/3 saving on memory.

Standard VGA uses a palette of 16 colours (4 bpp), each colour in the palette is 24 bit. Standard SVGA uses a palette of 256 colours (8 bpp).

Some graphics hardware and software support 32-bit colour depths, including an 8-bit "alpha channel" for transparency effects.
References in periodicals archive ?
Specific layers can be blended easily using the alpha map, which can be freely assigned to any of the six layers and which allows the assignment of 8 bits per pixel.
A comprehensive display mode supports many standard screen resolutions up to 1280 x 1024 at 60Hz with 24 bits per pixel color depth.
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It supports 1280x1024 resolution at 16 colors (4 bits per pixel -- or 8 bits for 256 colors with 2 MB of display memory), SVGA 1024x768 at 256 colors (8 bits), 800x600 at 256 or 65,000 colors (8 or 16 bits), and 640x480 at 8-bit, 16-bit or 24-bit "True Color.