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

EN Using Color Modes (Color LaserJet, 5, 5M, DeskJet) B-9
You need one plane or one bit/pixel for each power of two colors in the
palette. For example, a 256-color palette requires 8 planes or 8
bits/pixel (2
8
= 256).
Note Direct pixel encoding modes (2, 3) cannot be compressed using
raster compression modes 1 or 2. Planar pixel encoding modes (0, 2)
cannot be compressed using raster compression mode 5.
MODE 0: INDEXED BY PLANE
In mode 0 (default), successive planes of data are sent for each raster
row. A plane contains one bit for each pixel in a row. A pixel is not fully
defined until it has received all the planes for that row. The planes in a
row form index numbers that define a pixel by selecting a palette
entry. Assuming 3 bits per index, the underlined column of bits below
is the palette index for pixel 3 of row 1 (i1 is lsb; i3 is msb). Note that
the Transfer Raster Data by Plane command (
?*b#V) is used for all
planes except the last plane of each row, which uses the Transfer
Raster Data by Row command (
?*b#W).
?*b#V row 1 plane 1 i1 i1 i1 i1 i1
?*b#V plane 2 i2 i2 i2 i2 i2
?*b#W plane 3 i3 i3 i3 i3 i3
?*b#V row 2 plane 1 i1 i1 i1 i1 i1