It works in a similar way as a monochrome print, but with few differences:
1. User needs to send 3 rows of color bitstrings for each image row.
2. Printer will stay in place while printing all 3 non-white 'colors',
it will feed the paper each third line.
3. User must multiply height by 3.
4. Command is different: cmd[0] == ASCII_GS && cmd[1] == 118 && cmd[2] == 49
E.g.
For image 200x200, user needs to send header with width 200, height 600.
Image data is arranged the following way (fourth color is blank):
25 bytes (200bits) of 1st color for first row
25 bytes (200bits) of 2nd color for first row
25 bytes (200bits) of 3rd color for first row
25 bytes (200bits) of 1st color for second row
25 bytes (200bits) of 2nd color for second row
...etc...
