Run-length coding method for black-and-white facsimile with a ternary code as an intermediate step
U. Rothgordt · Electronics Letters · 1975
A code is presented that consists of codewords of variable length. This allows a good adaptation to the different run-length statistics of various kinds of documents: printed matter, drawings, weather maps etc. Compared with other run-length codes, the new code yields, in most cases, a better compression ratio.