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

EN Modifying Output Color (Color LaserJet, 5, 5M, DeskJet) D-9
Format
This byte should be set to 0.
Number of Planes
This byte designates how many dither matrices are specified by the
command. The command is ignored and the data discarded for any
value other than 1 or 3.
Height and Width
These bytes designate the size of the dither matrix in pixels. For
example, a value of four for height and six for width produces a dither
cell that is four pixels wide by six pixels high. Values must be non-zero
and sized so the matrix contains no more than 32767 bytes.
Otherwise, the command is ignored and the data discarded. The
minimum dither matrix size is 1 x 1.
Data Bytes
After specifying the height and width of the cell, data bytes are sent
row-by-row (row-major order). Each data byte contains the
normalized probabilities, ranging from 0 to 255, of one cell.
For example, a 2 x 2 cell could have no pixels print for RGB values of
205 through 255, one pixel for values of 153 through 204, two pixels
from 101 through 152, three pixels for 49 through 100, and all four
pixels between 0 and 48 (see the illustration below, which represents
a halftone cell for one of the primary colors—note that the color data
is in RGB values).
Byte Value Value Description
1 One matrix applied to all primaries
3 Each primary has a separate matrix