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. 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 that have a lot of 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 white pixels and black pixels which can be represented directly as a 0 and 1. These two symbols are too small a list of items to directly apply the Huffman coding. But if we first use run-length encoding we have can more objects to encode. Here is an example taken from the article on run-length encoding: