Epic 3000
Programmer’s Guide
Programming Codes
100-14362
Rev A
Page 79
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>
Byte wise RLE.
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.
Difference Compression
. 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.
Same-as-previous Compression
. In same-as-previous compression, the command
does not contain any graphics data. The command specifies that the printer is to use the
previous scan line data for the current scan line.
[ESC] h <1> <1> <255>.
