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Spot Color - Color Rendering Dictionary for Greater than Four Basic Colorants

IP.com Disclosure Number: IPCOM000118943D
Original Publication Date: 1997-Sep-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 35K

Publishing Venue

IBM

Related People

Decker, WC: AUTHOR [+3]

Abstract

Disclosed is a methodology for finding the percent of four basic colorants, such as cyan, yellow, magenta, and black, (C, Y, M, and K), to obtain a spot color using a color rendering dictionary. The sum of the percents of the four colorants must be equal to or less than 100 percent when using the color rendering dictionary approach. Thus, 20% C, 20% M, 20% Y, and 10% K is admissible but 30% C, 30% M, 30% Y, and 20% K is not admissible for a spot color application.

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Spot Color - Color Rendering Dictionary for Greater than Four Basic
Colorants

      Disclosed is a methodology for finding the percent of four
basic colorants, such as cyan, yellow, magenta, and black, (C, Y, M,
and K), to obtain a spot color using a color rendering dictionary.
The sum of the percents of the four colorants must be equal to or
less than  100 percent when using the color rendering dictionary
approach. Thus,  20% C, 20% M, 20% Y, and 10% K is admissible but 30%
C, 30% M, 30% Y, and 20% K is not admissible for a spot color
application.

      A problem arises with this methodology if one has, say, six
basic inks with which to obtain the six ink color rendering
dictionary.  If patches are taken in 20% increments for combinations
of each of the six colors, 46,656 patches would need to be generated.
This is far too many and would be prone to error in taking the data
and the analyses to obtain the color rendering dictionary.

      A shortcut can be taken that makes use of the fact that the
total colorant content cannot exceed 100% for spot color) (i.e.,
mixing the percents of colorants to obtain a particular spot color).
For the  example described, i.e., six colors and 20% increments of
all the colors,  the number of patches that need to be generated such
that the total percent of colorants is equal to or less than 100% is
only 462 patches.  This is arrived at from computing the admissible
possibilities.  It makes producing spot color inks from...