Design Nomenclature / Color
RGB
Also called red green blue
An additive model addressing color as amounts of red, green, and blue primaries. RGB by itself specifies nothing absolute: the same triplet means different colors on different devices until a space pins down the primaries, the white point, and the transfer curve. RGB without a profile is a coordinate with no map.
In practice
Used loosely to mean sRGB, which by default it usually is — an assumption that breaks the moment wide-gamut displays or camera raw enter the room.
Not to be confused with
- sRGBThe 1996 HP and Microsoft standard, written to describe a typical CRT and still the default assumption of the untagged web. Its gamut is small — it cannot reach a saturated cyan or a traffic-cone orange — but ubiquity made it the floor everything else gets measured against.
- CMYKThe subtractive process set: cyan, magenta, yellow, and a key black. Black is there because real inks are impure and CMY overprint gives a muddy brown, and because laying three wet inks where one would do is slow to dry, expensive, and blurs anything as fine as text.
- Additive colorMixing by summing emitted light: red, green, and blue primaries combine toward white, and every addition raises luminance. Screens, stage lighting, and projection work this way. The primaries were chosen to address the eye's three cone types — there is nothing special about those wavelengths in the physics.