Creation of a reverse look-up table from a forward look-up table for a color
device. Indexes to the forward look-up table span all possible color stimulus values
for the color device in a device dependent color space. Outputs from the forward
look-up table span a color gamut of corresponding color response values for the
color device in a device independent appearance color space. The reverse look-up
table maps a color response value in the device independent appearance color space
to a color stimulus value in the device dependent color space. Indexes to the reverse
look-up table span beyond the color gamut of color response values for the color
device, and outputs from the reverse look-up table span beyond all possible color
stimulus values for the color device. According to the invention, a first portion
of the reverse look-up table, in which indexes fall within the color gamut, is
populated by search and interpolation in the forward look-up table for color stimulus
values corresponding to color response values of the indexes to the first portion
of the reverse look-up table. A second portion of the reverse look-up table, in
which indexes fall outside of the color gamut, is populated by extrapolation from
extrapolation color stimulus values. The extrapolation color stimulus values are
found by search and interpolation in the forward look-up table for color stimulus
values corresponding to color response values near a boundary of the color gamut.
