Browse Prior Art Database

Color Rendering for Spot Colors

IP.com Disclosure Number: IPCOM000118816D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Decker Jr, WC: AUTHOR [+3]

Abstract

Disclosed is an invention which assumes that there are four or more primary inks available which can be mixed to obtain an ink having a desired color (spot color). In addition, there is a clear ink that is transparent.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 78% of the total text.

Color Rendering for Spot Colors

      Disclosed is an invention which assumes that there are four or
more primary inks available which can be mixed to obtain an ink
having a desired color (spot color).  In addition, there is a clear
ink that is  transparent.

      Typically, cyan, yellow, magenta and black inks are used as the
primary inks.  These inks all have the same physical properties such
as viscosity, surface tension, specific gravity, etc.  A series of
color patches is printed containing various percents of the primary
colors (cyan, yellow, magenta, and black).  The C.I.E. l*a*b* values
of each of these patches are measured.  From these measurements, a
Color-Rendering Dictionary (CRD) is developed using known inversion
and interpolation techniques.  Thus, any set of l*a*b* values can be
expressed as a function of the percents of the primary colors.  This
color-rendering dictionary can be thought of as the CRD used to
obtain a particular spot color.  Therefore, for a particular spot
color having a specific set of l*a*b* values, a combination of the
primary colors can be obtained that have the same l*a*b* values as
the spot color.  This is accomplished using the spot color CRD.

      If the printing mechanism is limited to a single pass of the
printhead, then it is important to realize certain limitations.  They
are that the total percent of the primary colors cannot exceed 100%
and that the total percent of ink must be 100%.  If the total pe...