Absolute Mode

The absolute mode is provided for sequences with varying contents. The minimum number of pixels in such a sequence is 3, the maximum 255. The absolute mode is indicated by an intial 0 followed by a value greater or equal than 3.

Coding scheme absolute mode:

Sequences providing an odd length will be treated in a special way. In this case the colour indices have to be terminated with 0, a value that is not part of the contents and will not be written to decoded data. This extension result in a word alignment as used in the entire scheme.

Example:

 encoded             decoded
 00 03 00 01 02 00   00 01 02
 00 04 00 01 02 03   00 01 02 03

Single or sequences of two pixels cannot be coded in absolute mode. Instead a run with the counter value 1 has to be used. This does not decrease compression efficiency because both the single pixel and the sequence of two pixels would require 4 byte coding in absolute mode.

Example:

 encoded             decoded
 01 00 01 01         00 01

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