Brother HL-Series Technical Reference Manual page 98

Revision C 16/01/96
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# = 1152 indicates that CCITT G3/G4 data compression is to be used.
This format is popular in optical document storage area as this compression is effective to store black and
white type pictures. As G3/G4 format does not have picture size/resolution information, the printer requires a
header at the beginning of the picture data. The header size is 94 Byte. Bothe the header and the picture data
are transferred by the ESC*b###W(###=data length) command. Normal PCL transfer graphics data command
has a limitatino of the data size and ### should not exceed 32767. Unlike other mode, this mode is special
and does not have the 32767 size limitation. The data must have the following structure - Header and Picture
data. The values in this mode are little endians.
Byte
position
0 - 1
2 - 3
4 - 7
8 - 11
12 - 13
14 - 15
16 - 19
20 - 21
22 - 55
56 - 59
60 - 61
62 - 63
64 - 65
66 - 67
68- 69
71 - 71
72 - 73
74 - 75
76 - 77
78 - 79
80 - 81
82 - 83
84 - 85
86 - 87
88 - 89
90 - 91
92 - 93
About CCITT G3/G4 data format, please refer to CCITT (The International Telegraph and Telephone
Consultative Committee) BLUE BOOK Volume VII.
Header
Picture data
Data Description
6E 6E 'nn' This is header ID.
0A 00 Reserved
5E 00 00 00 Picture data start offset from header top
File length File length including 94 Byte header. If file length is 65,536
byte, these 4 bytes become "00 00 01 00"
01 00 Reserved
01 00 Reserved
4A 00 00 00 Reserved
Compression mode 02 00: Fax MH format
03 00: Fax MR format
04 00: Fax G4 format
00 ... 00 All zero
Picture data length If picture data length is 65,442 (65,536 ~-94) byte, these 4 bytes
become "A2 FF 00 00."
01 00 bit / pixel
01 00 bit / pixel
Pixels/line If picture dot width = 2,400, these 2 bytes become "60 09"
Pixels/line Same as above.
Lines/picture If picture dot count = 3,100, these 2 bytes become "1C 0C."
Lines/picture Same as above.
00 00 Reserved
Photometrics 00 00 00 00 : data 0 = white
or 01 00 01 00 : data 0 = black
02 00 Reserved
Fill order 01 00 or 01 00 : filled from MSB
02 00 02 00 : filled from LSB
01 00 Reserved
00 00 Reserved
01 00 Reserved
Resolution 200, C8 00 00 00 : 200 dpi,
300, 400, 600 90 01 00 00 : 400 dpi,
400 and 600 dpi are available when printer operates in 600 dpi.
Resolution 200, C8 00 00 00 : 200 dpi,
300, 400, 600 90 01 00 00 : 400 dpi,
400 and 600 dpi are available when printer operates in 600 dpi.
02 00 Reserved
00 00 Reserved
Chapter 2 "PCL" - 83
94 bytes
File Length
Picture
data
length
2C 01 00 00 : 300 dpi,
58 02 00 00 : 600 dpi
2C 01 00 00 : 300 dpi,
58 02 00 00 : 600 dpi