HP PCL/PJL reference (PCL 5 Color) - Technical Reference Manual

EN Color Printing Overview (Color LaserJet, 5, 5M, DeskJet) A-15
Color Processing Functions
Given these two color uses, page marking primitives and color raster
data, color processing must:
Convert color attributes to an internal representation that can
be poured through the page marking stencil onto the
destination via some logical operation.
Convert multiple-bit-per-pixel color raster to an internal
representation that can be merged into the destination via
some logical operation.
Color processing must have access to the following state variables,
which indicate the form and attributes by which the two color groups
are generated.
Halftone (rendering algorithm)
RGB gamma correction
Device-dependent color lookup tables for each of the three
primaries
Appendix B describes in more detail how color raster data is
specified.