Epson GT-6500 EN - Manual (Page 53)

ESC B and other commands
The scanner ignores the image processing you select with the ESC B
command if you have already selected 3 bits/color/pixel or higher
with the ESC D command.
2. Download dither pattern (ESC b)
This command defines the dither pattern that is selected when you use
ESC B to select user-defined dither patterns A and B. You can select
square patterns with sizes of 4
Ч
4, 8
Ч
8, and 16
×
16. You define the
dither pattern by assigning a threshold data value to each pattern
member. Since image data has a value from 0 to 256, you can set the
threshold value from 0 to 256.
The threshold values you define with this command remain in effect
until you turn off the scanner or redefine new values. The ESC @
(Initialize the scanner) command does not clear these values.
Command Usage 2-15