from
The Free On-line Dictionary of Computing (8 July 2008)
grey-scale
<graphics> (US "gray-scale") 1. Composed of (discrete) shades
of grey. If the {pixels} of a grey-scale {image} have N
{bits}, they may take values from zero, representing black up
to 2^N-1, representing white with intermediate values
representing increasingly light shades of grey. If N=1 the
image is not called grey-scale but could be called
{monochrome}.
2. A range of acurately known shades of grey printed out for
use in calibrating those shades on a display or printer.
(1995-03-17)