Lexmark Printer manual Delta Row

2-91 PCL

Delta Row

Delta Row is a compression mode that identifies and transmits only those bytes different from the ones in a preceding row. The control byte consists of two parts:

•High 3 bits: Number of bytes to replace +1 (1 to 8).

•Low 5 bits: Offset from last unmodified byte (0-30); if the offset is 31, the next byte(s) is added to the offset until the next byte is not 255.

Example:

ESC*p300x1200Y	Move cursor to 1" x 4"
ESC*b3M	Set compression to Delta Row
ESC*r1A	Start raster graphics at current position
	Num Offset
ESC*b9W 'E0FFFFFFFFFFFFFFFF'x	'111 00000'b=8 at 0: 'FFFFFFFFFFFFFFFF'x
ESC*b9W 'E08000000000000001'x	8 at 0: '8000000000000001'x
ESC*b0W	No bytes change
...
ESC*b0W	No bytes change
ESC*b9W 'E0FFFFFFFFFFFFFFFF'x	8 at 0: '8FFFFFFFFFFFFFF'x
ESC*rB	End graphics