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

EN Modifying Output Color (Color LaserJet, 5, 5M, DeskJet) D-13
Color Lookup Tables
Color lookup tables provide a way to re-map color data for the
following types of applications:
• Highlight and shadow modification
• Saturation and desaturation
• Unique gamma correction curves
• Special effects for tonal correction
• Neutral balancing
Color lookup tables map input data for each primary color into a new
output range based on point-by-point conversions. Color lookup
tables can modify input data for both device-dependent and
device-independent color spaces.
Like the CID command, the first byte of the data field identifies the
color space to which the lookup tables will be applied. These tables
specify on a point-per-point basis a transformation from an input
space of 0 . . . 255 into an output space of 0 . . . 255. Figure D-1 on
the next page illustrates the concept.
The unity lookup table (see the following illustration) is the default for
all color spaces; it performs a 1:1 mapping of input to output (that is,
129 is mapped to 129). The inversion lookup table performs a simple
color inversion; for example, it inverts the red primary of a
device-dependent RGB color space to create cyan output (from 255
red to 0 red, which is 255 cyan).
Color Lookup Tables Command
This command enables and specifies color lookup tables.
?*l#W[binary data]
A value of 0 resets or initializes the color lookup tables for each
primary to the unity curve (1:1). A value of 770 means the data for a
color lookup table will be following. The command is ignored and the
data is absorbed for any number of bytes not equal to 0 or 770.
# = Number of bytes of binary data
Default =0
Range = 0 or 770 (command is ignored for other values; sign is
ignored)