Brother QL-720NW - Manual (Page 34)

Raster Command Reference
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4. Printing Command Details
M Select compression mode
ASCII: M {n}
Hexadecimal: 4D {n}
Parameters
Definitions of {n}
0 No-compression mode (Enabled)
1 Reserved (Disabled)
2 TIFF (Enabled)
Description
 Selects the compression mode. Data compression is available only for data in raster graphic transfer.
[TIFF(Pack Bits)]
 1-byte units
 If the same data is repeated, the number of data units and that 1 byte of data are specified.
If different data is in a series, the number of data items and all of the different data are specified.
 If the same data is repeated, the number of data units is specified as the actual number minus 1,
expressed as a negative number.
If different data is in a series, the number of data units is specified as the number of bytes minus 1,
expressed as a positive number.
 If the above process results in more than 90 bytes of compressed data, the data is treated as being all
different. As a result, the data will be 91 bytes, including the 1 byte that specifies the data length.
Example
1 raster of raster graphics transfer:
Without compression: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00 00 00 00 00 22 22 23 BA BF A2 22 2B……
With compression: ED 00 FF 22 05 23 BA BF A2 22 2B …
a b c
a. Since “00h” is repeated for 20 bytes, 20d -> 19d -> 13h changed into a negative number is EDh.
Therefore: ED 00
b. Since “22h” is repeated for 2 bytes, 2d -> 1d -> 1h changed into a negative number is FFh.
Therefore: FF 22
c. The following 6 bytes remain unchanged. 6d -> 5d -> 5h
Therefore: 05 23 BA BF A2 22 2B
Continue for the remaining number of bytes for the uncompressed data. Even if 00h continues until the
end, it cannot be omitted.