Appeal No. 1998-2679
Application No. 08/148,765
printable CMY image. Other types of color spaces exist that
are not defined by color primaries but which are defined by
other characteristics. For example, the color space u'v'L* is
a color coordinate space defined by chromaticity coordinates
(u'v' [hue and saturation respectively] in which equal
differences approximately represent equal perceived color
differences for color stimuli having the same luminance and
CIE psychometric lightness function (L*). Another space is
the L*a*b* color coordinates space where again, equal
differences in a* and b* present approximately equal perceived
color differences for color stimuli having the same luminance.
Because the defining characteristics of the various color
spaces are different, transforms within the color spaces are
different. The present invention takes advantage of the
different characteristics of the color spaces to process
images to improve the shadow-to-highlight characteristics for
both neutral and colored objects contained within the image.
In the transform from one color space, say scanner RGB, to
another color space, say printer CMY, it is common to apply
some sort of nonlinear transformation that is designed to
compensate for physical and psychophysical factors affecting
appearance of the reproduced image. This transform is
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