Files with the RLE extension are used for storing bitmap images. The data in such an image is encoded in a way that reduces the file size. It consists in that repeated data is represented by a repetition counter, eg the string "cccccccc" is coded as "8c". Such encoding is the more effective the more areas of an image defined by the same data are repeated (e.g. a large background area of the same color).

RLE (Run-Length Encoding) compression is used for saving images such as PCX, BMP or TGA.