MTF
MTF is the abbreviation for the Move-to-Front transform, which converts BWT output into many small integers and creates a favorable distribution for entropy coding.
Purpose
After BWT, it turns character clustering into index clustering so that frequent characters map to small indices.
Mechanism
Maintain a symbol table, output each symbol's current index, then move it to the front. The inverse transform runs the same table operations to recover the original symbols.
Use cases
- The bzip2 pipeline
- Post-processing after BWT
- Locality-aware coding