Brother 1660e - B/W Laser Printer, User Manual

Page: 247 / 271

APPENDICES
Appendix–53
The block data is composed as follows:
Position Data Description
0 - 1 Block length n - 2
2 - 3 Horizontal position dots from the left of the page
4 - 5 Vertical position dots from the leading edge of the page
6 Height dots number of image vertical dots
7 - 8 Width words number of image horizontal 16 bit
words
9 - (n - 1) Compression data compression image 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 800 bytes;
ESC*b809W 03h 27h 01h 00h 00h 40h 20h 00h 64h [Data800Byte]

_
 
_
 
_

|

_

|
a b c d e f
<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.
y 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 4 3 0
0 data word count (11 bits) not used
data 1 (16 bits)
:
data n (16 bits)
(256, 64)
32
1600
0
64
128
Band 1
Band 2
a: Block length(807)
b: Horizontal position(256)
c: Vertical position(64)
d: Height dots(32)
e: Width words(100)
f: Compression image data