Epson AcuLaser C4000 Reference Manual page 218

Bit Image
The printer is able to emulate the graphics densities set with the
printer commands. If you select
high, and if you select
If you select
by automatically filling in any vertical gaps between dots. This
produces unbroken vertical lines that can be read by a bar code
reader. This mode will reduce the size of the image being printed,
and may also cause some distortion when printing bit image
graphics.
ZeroChar
Selects whether the printer prints a slashed or unslashed zero.
Character Set
Selects character table 1 or 2.
206 Functions of the Control Panel
, the bit image density is low.
, the printer converts bit images to bar codes
, the bit image density is