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Color-Rendering Dictionary Accuracy in Critical Areas

IP.com Disclosure Number: IPCOM000118811D
Original Publication Date: 1997-Jul-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Decker Jr, WC: AUTHOR [+3]

Abstract

In the formulation of color-rendering dictionaries, patches of varying amounts of cyan, yellow, and magenta are printed. Typically, equal increments of cyan, yellow, and magenta are employed. Using standard inversion and interpolation techniques, a color-rendering dictionary is obtained where C.I.E. l*a*b* values are expressed in terms of percents of cyan, yellow, and magenta. The human eye can perceive small color differences in the gray areas, as well as in areas where the hue is associated with equal amounts of yellow and magenta.

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Color-Rendering Dictionary Accuracy in Critical Areas

      In the formulation of color-rendering dictionaries, patches of
varying amounts of cyan, yellow, and magenta are printed.  Typically,
equal increments of cyan, yellow, and magenta are employed.  Using
standard inversion and interpolation techniques, a color-rendering
dictionary is obtained where C.I.E. l*a*b* values are expressed in
terms of percents of cyan, yellow, and magenta.  The human eye can
perceive small color differences in the gray areas, as well as in
areas where the  hue is associated with equal amounts of yellow and
magenta.

      In order to minimize color-shift errors that can be perceived
by humans, finer increments of cyan, yellow, and magenta are taken in
these critical areas when printing the initial color patches.  All
the other increments of cyan, yellow, and magenta are taken at the
normal increments.  For instance, instead of taking 10% increments of
cyan, yellow, and magenta at their lower values (below 20%),
increments of 2% are taken when printing the color patches required
for the color-rendering dictionary creation.  Thus, increments of 2%,
4%, 6%, 8%,  etc., up to 20%, of cyan, yellow, and magenta are
employed in this critical/sensitive area of the color gamut.  The
limitation in performing  this is that the nodal points of the
smaller increments must line up with those of the larger increments
(i.e., they are a submultiple of the larger increments).