6E 6E - Page 103

2001/10/02 

CHAPTER 2 "PCL" - 83 

<Second section  66 66 66 66> 

Offset count = 2 
Replacement count = 4 
Replacement data = 66 

1

1

1

0

0

0

0

1

7

6

5

4

3

2

1

0

Replacement count = 1 + 2 = 3

Offset count = 3

Optional offset count byte = 0

Replacement data = 11

1

1

0

0

0

1

0

7

6

5

4

3

2

1

0

Replacement count = 2 + 2 = 4

Offset count = 2

Replacement data = 66

0

• 

# = 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 t he 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 
position 

Data 

Description 

0 - 1 

6E 6E 

'nn' This is header ID. 

2 - 3 

0A 00 

Reserved 

4 - 7 

5E 00 00 00 

Picture data start offset from header top 

8 - 11 

File length 

File length including 94 Byte header.  If file length is 65,536 byte, 
these 4 bytes become "00 00 01 00" 

12 - 13 

01 00 

Reserved 

14 - 15 

01 00 

Reserved 

16 - 19 

4A 00 00 00 

Reserved 

20 - 21 

Compression mode 

02 00: Fax MH format 
03 00: Fax MR format 
04 00: Fax G4 format 

22 - 55 

00 ...  00 

All zero 

56 - 59 

Picture data length 

If picture data length is 65,442 (65,536 ~-94) byte, these 4 bytes 
become "A2 FF 00 00." 

60 - 61 

01 00 

bit / pixel 

62 - 63 

01 00 

bit / pixel 

64 - 65 

Pixels/line 

If picture dot width = 2,400, these 2 bytes become "60 09" 

66 - 67 

Pixels/line 

Same as above. 

68- 69 

Lines/picture 

If picture dot count = 3,100, these 2 bytes become "1C 0C." 

Header 

Picture data 

94 bytes 

Picture 
data  
length 

File Length