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Proofing Printer Color Rendering Dictionary

IP.com Disclosure Number: IPCOM000118416D
Original Publication Date: 1997-Feb-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 57K

Publishing Venue

IBM

Related People

Lee, HC: AUTHOR [+2]

Abstract

Disclosed is a methodology for allowing a given color printer to simulate another via the use of a special color transform table.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Proofing Printer Color Rendering Dictionary

      Disclosed is a methodology for allowing a given color printer
to simulate another via the use of a special color transform table.

      It is desirable to have one color printer (proofer) print in a
manner that simulates a second color printer (original).  There can
be two types of inputs to the proofing printer.  One is in the form
of the c(cyan), y(yellow), m(magenta), k(black) colors that would be
sent to the original printer.  The other input could be in the form
of device independent color coordinates, i.e., l*,a*,b* that would to
be sent to the original printer.  For the former case, the values of
c,m,y,k that would be sent to the original printer have to be
converted to equivalent c,m,y,k values that are sent to the proofer
printer. Thus,  a table or color transform is required to convert
c,y,m,k original to c,y,m,k proofer.  Color patches are printed on
each printer that have various percentages of the c,m,y,k colorants.
The l*,a*,b* values are  measured for each of these patches.  First,
for the original printer a table or color rendering dictionary is
formed by inversion and interpolation such that the l*a*b* values are
now expressed in terms of  the cmyk values for the original printer.
Additionally, values of l*a*b*  that are out of the color gamut of
the original printer are gamut mapped  via an appropriate technique
(l*a*b* out of gamut values are mapped into  l*a*b* values that are
in gamut).

      A similar procedure is followed for the proofer print...