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

B-8 Using Color Modes (Color LaserJet, 5, 5M, DeskJet) EN
Note Colorimetric RGB color spaces are based on the 1931 standard
2-degree observer and specified by CIE xy chromaticity coordinates.
They use the standard D6500 viewing illuminant and a 45-degree
illumination model with a 0-degree collector geometry for reflective
data.
CIE L*a*b* is the CIE 1976 Uniform Color Space based on the 1931
standard 2-degree observer, and using a 45-degree illumination
model with a 0-degree collector geometry for reflective data. The
viewing illuminant is the standard D6500 illuminant.
Luminance-Chrominance spaces are a 3x3 linear transformation from
Colorimetric RGB. Like CIE L*a*b*, achromatic data is contained in
one channel and chromatic data shares the other two channels.
Note HP Color LaserJet 5 and 5M printers parse and discard the CID
command when Colorimetric RGB spaces are specified. Rather than
creating a Colorimetric RGB palette, a device RGB palette is created,
but it is populated with the default color of the Colorimetric RGB
palette. In addition, the ScreenMatch color table is selected to give
the impression of Colorimetric RGB behavior while working in a
device-dependent space
Byte 1 (Pixel Encoding Mode)
Byte number 1 designates the format in which raster data is to be
transmitted and interpreted. The range of this value field is 0 to 3. All
other values for this field are ignored.
Byte Value Pixel Encoding Mode Restrictions
0 Indexed by Plane
(default)
Bits/index must be
1, 2, 3, 4, 5, 6, 7, or 8
1 Indexed by Pixel Bits/index must be
1, 2, 4, or 8
2 Direct by Plane 1 bit per primary
(RGB or CMY only)
3 Direct by Pixel 8 bits per primary
(All Color Spaces)