Brother HL-1050 Technical Reference Manual page 101

<Second section 66 66 66 66>
Offset count = 2
Replacement count = 4
Replacement data = 66
7 6 5 4 3
1 1 1 0 0
Replacement count = 1 + 2 = 3
Offset count = 3
7
1 1
•
# = 1152 indicates that CCITT G3/G4 data compression is to be used.
This format is popular in optical document storage areas 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 Bytes. Both the header and the picture
data are transferred by the ESC*b###W(###=data length) command. The normal PCL transfer graphics data
command has a limitation on the data size and ### should not exceed 32767. Unlike other modes, 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 Data
position
0 - 1 6E 6E
2 - 3 0A 00
4 - 7 5E 00 00 00
8 - 11 File length
12 - 13 01 00
14 - 15 01 00
16 - 19 4A 00 00 00
20 - 21 Compression mode
22 - 55 00 ... 00
56 - 59 Picture data length
60 - 61 01 00
62 - 63 01 00
64 - 65 Pixels/line
66 - 67 Pixels/line
68- 69 Lines/picture
71 - 71 Lines/picture
2 1 0
0 0 1 Optional offset count byte = 0
6 5 4 3 2 1 0
0 0 0 0 1 0
Replacement count = 2 + 2 = 4
Offset count = 2
Header
94 bytes
Picture
data
Picture data
length
Description
'nn' This is header ID.
Reserved
Picture data start offset from header top
File length including 94 Byte header. If file length is 65,536 byte,
these 4 bytes become "00 00 01 00"
Reserved
Reserved
Reserved
02 00: Fax MH format
03 00: Fax MR format
04 00: Fax G4 format
All zero
If picture data length is 65,442 (65,536 ~-94) byte, these 4 bytes
become "A2 FF 00 00."
bit / pixel
bit / pixel
If picture dot width = 2,400, these 2 bytes become "60 09"
Same as above.
If picture dot count = 3,100, these 2 bytes become "1C 0C."
Same as above.
CHAPTER 2 "PCL" - 81
Replacement data = 11
Replacement data = 66
File Length
2/19/04