Modified Huffman coding

Modified Huffman coding is used in fax machines to encode black-on-white images (bitmaps). It combines the variable-length codes of Huffman coding with the coding of repetitive data in run-length encoding.

The basic Huffman coding provides a way to compress files with much repeating data, like a file containing text, where the alphabet letters are the repeating objects. However, a single scan line contains only two kinds of elements