CIE
Division 8 - TC8-03: Survey of Gamut Mapping Papers
Lamming & Rhodes (1990)
The approach used in this paper is strictly intended for matching a monitor
and a printed medium and uses iterative empirical methods to obtain LUTs
for transforming RGB to CMYK. Its lightness mapping relies on two LUTs
- one between RGB and L* and the other between CMY and L* (all the patches
for obtaining the LUT are achromatic, as the lightness mapping is thought
to be similar for chromatic and achromatic colours). Out-of-gamut colours
are modified by transforming all colours using the following matrix:
Here A is a 3x3 matrix, which starts off as being an identity matrix
and is then iteratively modified by the user so as to improve the appearance
of the reproduction. To maintain the grey balance, the sum of the terms
in each row needs to be equal to one. Note, that the matrix can be used
for adjusting both saturation and hue.
For the majority of applications where accuracy is of importance, this
method is not particularly useful as its performance depends heavily on
the skills of the person setting up the transformation matrix by trial
and error.
Last updated: 17 August 1999 by Jan
Morovic