Graphics Compression - TransAct POSjet 1500 Programmer's Manual

Control Codes
Function Set horizontal graphic mode
ASCII [ESC] * <m> <0> <0>
Hexadecimal
1BH 2AH <m> <0> <0>
Decimal
<27> <42> <m> <0> <0>
IPCL
none
Description
The [ESC] * <m> <0> <0> command selects one of the three graphic modes specified by <m>.
The two bytes after the mode must be zero.
Where <m>
0,2,3,4,5,6,7
8,9
10
11
12
13
14,15,16 Not supported
Note 1
Only modes 10 thorough 13 should be selected for horizontal graphics.
Example Command
ESC * <10> <0> <0>
ESC h <1> <9> <0> <eight data bytes>
ESC h <2> <9> <0> <eight data bytes>
ESC h <3> <9> <0> <eight data bytes>
LF
Note 2 Graphic data is committed to paper when more than 12 dot rows have been transmitted to the
printer. If less than 12 dot rows have been sent, they are not printed until the line is terminated
(i.e. a line feed command is sent). To make graphics faster to send and smaller to store, several
algorithms are included with the graphic command to compress the data.

Graphics Compression

Although the printer compression algorithms are documented, it is recommended that our Windows printer driver be
used to generate a graphic image. Our Windows printer driver selects the best compression method to use on a scan
line by scan line basis. The print driver can be directed to print to file, creating a .prn file. When creating a .prn file,
it is recommended that the Start/End Doc settings be cleared in the Start/End Doc tab of the printer properties page.
After the .prn file is created, it can be read and sent to the printer by the host application.
Bit wise RLE
In bit wise RLE compression, the Most Significant Bit (MSB) Compression of each data byte denotes if the
compressed data represents one or zero bits. Bits zero through six indicate how many bits are represented as a one
or zero. A 34 Hex (34H) represents 34H bits set to zero. A 97H represents 17H bits set to one.
ESC h <1> <5> <1> <34H> <97H> <8fH> <09H>
In byte wise RLE compression, data is represented in byte Compression pairs. The first byte is a count, and the
second is the graphics data. The graphics data byte is repeated the number of times represented by the count byte.
ESC h <1> <5> <8> <09H> <FFH> <02H> <55H> Where <09H> <FFH> means repeat FFH nine times and <02H>
<55H> means repeat 55H two times.
In difference compression, data is represented in byte pairs. In compression, the first byte is an index into the byte
stream, as it would exist if sent in an uncompressed format. The second byte is the data that is different in the new
scan line data. Think of compression mode as, "The scan line is the same as the previous except for the byte at a
specific position." ESC h <1> <5> <254> <03H> <d5H> <0bH> <51H> Where <03H> <d5H> means use the
previously transmitted scan line data but change byte 3 to a d5H and change byte 11 (0bH) to a 51H.
Page 144
POSjet
Standard Graphic Modes (See above.)
Not supported
104 x 96 dpi
208 x 96 dpi
104 x 192 dpi
208 x 192 dpi
Send line feed to force print of any buffered data not yet printed.
Rev M
®
1500
1 horizontal, 1 vertical pass
2 horizontal, 1 vertical pass
1 horizontal, 2 vertical passes
2 horizontal, 2 vertical passes
Comment
Set resolution to 100 x 96 dpi.
Send 8-bytes red pixels.
Send 8-bytes green pixels.
Send 8-bytes blue pixels.
Programmer' s Guide
Nov-07