Run-length encoding
From Just Solve the File Format Problem
Run-length encoding (RLE) is a simple kind of data compression, in which a run of consecutive equal data values is replaced by a code indicating the run length and the data value.
RLE can be effective for some types of data, or as part of a more sophisticated algorithm, but by itself it is a poor general-purpose compression algorithm.
RLE is used in countless raster graphics formats.
Related formats
Algorithms and compressed data formats based primarily on RLE:
Note that most RLE implementations are used in only one format, and are not documented in a separate article.
