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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
C
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.
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 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