Indexed color technique

In computing, indexed color is a technique for managing digital images colors' in a limited way, in order to save computer memory and file storage, while speeding up the transfer of files and screen refresh. It is a form of compression vector quantization.

When a picture is encoded in this manner, the color information is not performed directly by the pixel image data, but is stored in a separate data part called a palette: an array of color elements. Each element of the array represents a color, indexed by their position within the matrix. Individual tickets are known as color registers. The pixels of the image does not contain the complete specification of their color, but only its index in the palette. This technique is sometimes referred to comopseudocolor [1] or indirect color, [2] as colors are addressed indirectly.

Perhaps the first device that supports color palette was a frame buffer random access, described in 1975 by Kajiya, Sutherland and Cheadle. [3] [4] This supports a palette of 256 colors, 36-bit RGB.

Color depth, also called bit depth, or the number of bits used to indicate the color of a single pixel in a bitmapped image or video frame buffer, or the number of bits used for each color component of a single pixel. [1] [2] [3] [4] For consumer video standards, such as High Efficiency Video Coding (H.265), the depth specifies the number of bits used for each color component bits. [1] [2] [3] [4] When referring to the term pixel may be defined as bits per pixel (bpp), which specifies the number of bits used. When referring to a color component is the concept can be defined as bits per channel (bpc), bits per color (tcf), or bits per sample (bps). [1] [2] [5] The color depth is only one aspect of color representation, expressing how finely color levels can be expressed (aka color accuracy); the other aspect is the amplitude can express a range of colors (spectrum). The definition of both the color accuracy and range is carried out with a specification of color coding that assigns a value of digital code to a location on a color space.