Lexmark X422 Technical Reference Manual page 71

Run-Length Encoded Data
Run-Length Encoded Data is interpreted in pairs of bytes. The first byte:
•
•
•
•
Example:
ESC
ESC
ESC
ESC
ESC
ESC
ESC
ESC
ESC
Tagged Image File Format
TIFF "Packbits" contain a control byte (a signed number) that indicates whether the
raster data bytes are to be repeated (up to 127 times) or printed as encoded data.
•
•
Example:
ESC
ESC
ESC
ESC
ESC
ESC
ESC
ESC
ESC
Acts as a counter, or control byte.
Indicates how many times to repeat the data in the second byte.
Can be from 0 (no repetition) to 255.
The second byte is the data byte.
For control values of 0 through 127, the next (Control+1) byte(s) is uncoded.
For control values of -1 through -127 ('FF'x - '81'x), the next byte is repeated
(Abs(Control)+1) times.
2-59
|Move cursor to 1" x 2"
|Set compression to Run-Length
|Start raster graphics at current position
|Run-Length: 8x'FF'x
|1x'80'x, 6x'00'x, 1x'01'x
|1x'80'x, 6x'00'x, 1x'01'x
|
|1x'80'x, 6x'00'x, 1x'01'x
|8x'FF'x
|End graphics
|Move cursor to 1" x 3"
|Set compression to TIFF
|Start Raster Graphics at current position
| TIFF: 8x'FF'x
|1:'80'x, 6x'00'x, 1: '01'x or
|8: '8000000000000001'x
|
|1:'80'x, 6x'00'x, 1: '01'x
|8x'FF'x
|End graphics
PCL