Color depth number of bits used for the color of a pixel

Color depth (also known as bit depth) refers to the number of bits used for the color of a pixel or used for every color component of a pixel. Low color depth stores a value which represents the index into a palette whose colors are fixed by the hardware. There also are pseudocolor palettes which are changeable. When the number of bits rises, the color value can encode relative variations of brightness of red, green and blue to refer to a color in the RGB model. Color systems such as 8-bit color, high color (15/16-bit) and 18-bit are pretty limited, while true color (24-bit) or deep color (30/36/48-bit) can provide millions or billions of colors. All TV and computer displays form images based on red, green and blue.