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

A-4 Color Printing Overview (Color LaserJet, 5, 5M, DeskJet) EN
Device-Dependent vs. Device-Independent
Color
Device-dependent color spaces are relative to the device’s ability to
produce specific colors. For example, if red is specified in a
device-dependent color space, two different printers will combine the
same amounts of cyan, magenta, yellow, and black toner to produce
the color, but the results will be different because of the different
properties of the toner.
Device-independent color is specified absolutely, in a color coordinate
system that is independent of any device. For example, if red is
specified in a device-independent color space, two printers will always
produce the same result, even though they may need to combine
different amounts of cyan, magenta, yellow, and black toner. Printers
that produce device-independent color are calibrated to precise color
standards.
Black and White References
Device-dependent color specifications are based upon an arbitrary
range of values for each primary color component. The range
endpoints for each color component are called black and white
references for that component. Colors relative to these predefined
limits are derived by specifying the amount of each component.
For the Device RGB color space, the maximum limit is called the
white reference and the minimum limit is called the black reference.
Regardless of the number chosen, the white reference represents the
maximum value of a primary color that a device can produce, and the
black reference represents the minimum value of that primary color.
For example, if 100 is chosen as the white reference for red in the
RGB color model, it represents the reddest red the device can
produce. If 10 were chosen instead, then 10 would represent the
same red.