Monarch 9400 Series manual Compressing the Data Stream

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: 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).

3.Each row of the matrix is terminated by the command inter-record separator, split vertical bar ( p ). However, the 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