Epson GT-6500 EN - Manual (Page 54)

To determine the data for a typical spiral dither pattern like the one
shown in figure a, multiply the threshold value by 16 and add 8; the
results are the values shown in figure b. The data is then sent in the
order shown in figure c.
3. Set color correction (ESC M)
Color correction adjusts the colors to match those available on your
output device.
The color produced by different output devices varies depending on
the method used to express color. You can use this command to
correct colors to match various output devices.
The following output devices can be selected with this command.
❏ Dot-matrix impact printers
Use for color impact printing.
❏ Thermal printers
Use for color thermal printing.
❏ Ink-jet printers
Use for color ink-jet printing.
2-16 Command Usage