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9400 Series Programmer's Manual
Compressing the Data Stream
Image data usually consists of a large amount of repetitive
data. Therefore, the printer uses a data compression
algorithm for the graphic message structure. Here's how it
works.
1. Any image is defined as a matrix of cells.
2. Each row of the matrix consists of a series of consecutive
ON (black) or OFF (white) cells. The range is 1-26,
represented by adding either a hex 40 (black) or hex 60
(white). Cells that print black will be represented by the
upper case letters 'A' through 'Z' in the file sent to the
printer. Cells that print white will be represented by the
lowercase letters 'a' through 'z' in the file sent to the
printer. Consecutive cells greater than 26 require multiple
letters.
Example:
3. Each row of the matrix is terminated by the command
inter-record separator, split vertical bar (
last row of the matrix ends with the TERMINATOR
command, closed brace (}).
4. In addition to compressing consecutive cells, repetitive
lines of compressed row data can be combined. For
example, if twelve rows have the same data (;zm), a
number can be added at the beginning of the line to repeat
the line (;12zm).
The following example shows how you can compress the
"Letter A" data stream. The long version is on the left. The
compressed version of the same data stream is on the right.
5-12
39 consecutive white cells would be
represented by the letters 'zm' (i.e. 'z'
produces 26 white cells followed by 'm' or
13 more white cells).
). However, the
p
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