Run Length Encoding (RLE)

Run Length Encoding is one of the oldest compression methods. It is characterized by the following properties:

• Simple implementation of each RLE algorithm
• Compression efficiency restricted to a particular type of contents
• Mainly utilized for encoding of monochrome graphic data

The general algorithm behind RLE is very simple. Any sequence of identical symbols will be replaced by a counter identifying the number of repetitions and the particular symbol. For instance, the original contents 'aaaa' would be coded as '4a'.

The most important format using RLE is Microsoft bitmap (RLE8 and RLE4).