DLI Implementation and Reference Guide - Datalogics

Color and its Use 12.17
"C" Example: Collapsing CMYK to Gray
if (State->fillColorSpec.space) == GlobalCMYKSpace)
{
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;
State->fillColorSpec.value.color[0] =
(fixedOne - (State->fillColorSpec.value.color[0] +
State->fillColorSpec.value.color[3]));
if (State->fillColorSpec.value[0] < 0)
State->fillColorSpec.Value[0] = 0;
}
}
Converting RGB to CMYK
RGB and CMY are complements, so we can turn one to the other by subtracting the
value from 1. However, the “K” component of CMYK (Black) is present to enhance
the distribution of ink on a printer, and should be maintained correctly across such
conversions.
In converting RGB to CMYK, we complement each of the channels, then identify the
smallest of the three values, subtract it from each channel, and use it as the value for
channel 4.