Paxar 9474 User Manual download pdf (Page 48)

Clear Image Buffer

This command clears all or selective graphics from the image

buffer. Once graphic data is sent to the printer, that graphic stays

in memory until a clear image buffer command is sent.

Syntax

{ C## }

Field

Contents

Must be the letter ‘C’ to identify the clear image buffer

command.

## This optional parameter specifies a particular graphic to be

cleared from memory. It must match the number assigned in

the graphic data stream. If omitted, ALL graphics in memory

will be deleted.

Example

{C} Clears all graphics from the printer.

{C4} Clears only graphic number 4.

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.

Any image is defined as a matrix of cells.

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 are represented by the upper case letters ‘A’

through ‘Z’ in the file sent to the printer. Cells that print white

are represented by the lowercase letters ‘a’ through ‘z’ in the

file. Consecutive cells greater than 26 require multiple letters.

Example: 39 consecutive white cells are represented by

the letters ‘zm’ (i.e. ‘z’ produces 26 white

cells followed by ‘m’ or 13 more white cells).

4-8 Using Graphics

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Paxar 9474 User Manual Page 48