3.1.6 Run-Length Encoding (RLE) Compression
In general, run-length encoding (RLE) compression makes it possible to specify an arbitrary number of identical values without a proportional increase in storage requirements. The compressed format usually defines a run count and a value, and expansion amounts to replicating that value a number of times equal to the run count.
Metafile records can contain bitmaps that are compressed with an enhanced RLE compression algorithm. Compression of bitmaps that are defined with 4 and 8 bits per pixel are described in the sections which follow.