The colors vocabulary defines a protocol for colors, with a concrete implementation for RGBA colors. This vocabulary is used by io.styles, ui and other vocabularies, but it is independent of them.

RGBA colors with floating point components in the range [0,1]:

<rgba> ( red green blue alpha -- rgba )

Converting a color to RGBA:
>rgba ( color -- rgba )

Extracting RGBA components of colors:
>rgba-components ( object -- r g b a )

Further topics:
Color protocol
Standard color database

Color implementations:
CIE 1931 XYZ colors
CIE 1931 xyY colors
CIE 1976 LAB colors
CIE 1976 LUV colors
CMYK colors
Grayscale colors
HSL colors
HSV colors
RYB colors
YIQ colors
YUV colors