DLI Implementation and Reference Guide - Datalogics

12.16 DLI Implementation and Reference Guide
Conversion between Models
Concepts and Facilities: Guide to the DL Pager Composition System
On some occasions, it is useful to be able to convert color values between color
spaces. This does not occur often, as most composition engines permit only a single
definition of color, but you may occasionally, for example, need to collapse colors to
fewer models, such as when using grayscale in place of RGB when the color selected is
a gray.
The folowing examples assume a gray image encoded as RGB or CMYK.
Collapsing RGB to Gray
If all three channels of the RGB color are the same value, then the color specified is a
gray. It may be simulated in gray by using that value as the gray color value.
"C" Example: Collapsing RGB to Gray
if (State->fillColorSpec.space) == GlobalRGBSpace)
{
if ((State->fillColorSpec.value.color[1] ==
State->fillColorSpec.value.color[2]) &&
(State->fillColorSpec.value.color[2] ==
State->fillColorSpec.value.color[3]))
{
State->fillColorSpec.Space = GlobalGraySpace;
}
}
Collapsing CMYK To Gray
If the first three channels of the CMYK color are the same, then the color is gray. The
amount is 1 minus the sum of one of the first three channels, plus the fourth channel.
If this is less than zero, then the amount is zero.