Brother HL-2060 User Manual page 263

The block data is composed as follows:
Position Data
0 - 1 Block length
2 - 3 Horizontal position
4 - 5 Vertical position
6 Height dots
7 - 8 Width words
9 - (n - 1) Compression data
Ex.) Data is at horizontal position = 256, vertical position = 64,
height = 32 dots, width = 100 x 16 bit words (1600 dots), and
compression data is
ESC*b809W 03h 27h 01h 00h 00h 40h 20h 00h 64h [Data800Byte]
_
a
0
(256, 64)
64
1600
128
<Compressed Image Data>
Data compression compresses the original image data word by word (16
bits).
The compressed data consists of both horizontal compression which uses
16 bit, 8 bit and 4 bit repeating patterns within 1 word or 2 words of data,
and vertical compression which indicates to repeat the same data as in the
previous line with 1 word of data.


Non-compressed data
When the most significant bit in the first 2 bytes is 0, the printer goes into
non-compression mode. The following 11 bits then indicate the number of
words of data, and the least significant 4 bits are not used. After that, the
image data follows word by word.
15 14
0 data word count (11 bits)
Description
n - 2
dots from the left of the page
dots from the leading edge of the
page
number of image vertical dots
number of image horizontal 16 bit
words
compression image data
800 bytes;
_ _ | _
b c d e
a: Block length(807)
Band 1
b: Horizontal position(256)
c: Vertical position(64)
32
d: Height dots(32)
Band 2
e: Width words(100)
f: Compression image data
data 1 (16 bits)
:
data n (16 bits)
APPENDICES
|
f
4 3 0
not used
Appendix–55