Alternatively referred to as pixel depth, color depth refers to the number of bits per pixel on a computer monitor to represent a specific color. The more bits per pixel, the higher color variety and quality of the monitor. The first graphics cards and monitors supported 1-bit color, which was monochrome (most commonly black and white), for early computers like the Apple Macintosh and Atari ST.
Today, most computers support at least 32-bit color, which allows for up to 16.7 million colors. Windows 7 introduced support for 48-bit color, assuming the computer's video card supports this color depth.
Evolution of color depth
As technology and available system resources have increased so has the color depth. Below is a listing of all of the different color depths over the history of computers.
- 1-bit (21 or 2 colors) - Monochrome displays.
- 2-bit (22 or 4 colors) - CGA displays.
- 4-bit (24 or 16 colors) - EGA displays.
- 8-bit (28 or 256 colors) - VGA displays.
- 16-bit (216 or 65,536 colors) - XGA displays.
- 24-bit (224 or 16,777,216 colors) - SVGA displays.
- 32-bit (16,777,216 colors + Alpha channel (232 or 4,294,967,296 color combinations))
- 48-bit (248 or 281,474,976,710,656 colors)