Greyscale
You can think of the greyscale as the brightness dimension of the HSB scheme (or the axis of the HSB cone)—with saturation held to zero, and hue therefore meaningless. The greyscale is used by photographers, and it is also useful in many documents where variations in gray can be used in place of costly color printing.
Our eyes can actually distinguish about ten different shades of grey, a phenomenon which has been described most eloquently by the famous photographer Ansel Adams, with his “Zone system” of black-and-white negative exposure and print making.
The only possible confusion with a grey scale—always described in percent—is to distinguish between the brightness scale (black = 0, white = 100) and the complimentary scale (100 minus brightness) that printers and photographers use to describe it.
• Black = 0% brightness, 100% grey.
• White = 100% brightness, 0% grey.
• Grey is most often specified from white = 0, thus 10% grey = 90% brightness.