4-bit color
From The Glossary of Digital Photography
Also called 16 colors. A color system in which each pixel is represented by 4 bits. This means that each pixel can be 16 (24) possible colors. This is similar to a 3-bit color system, in which there is one bit for each of the three colors: red, green, and blue. In addition, there is a 4th bit for intensity. The following colors are possible in 4-bit color: black, blue, green, cyan, red, magenta, brown, light gray, dark gray, bright blue, bright green, bright cyan, bright red, bright magenta, yellow, bright white. This color system has some use on IBM PC-compatible computers and in the Windows operating system. Most common systems use more bits today so more colors can be represented.
