wmf files are often stored compressed compressed with lz compression in word files <quote from documentation> They are normally stored in a compressed format using the LZ compression algorithm in the format used by GNU Zip deflate/inflate with a 32k window. The format is zlib format . The only metafile compression version number currently defined identifies this format and is analogous to the PNG compression type value in the PNG file format. </quote> Peter Brandstrom - D/Z <peter.brandstrom@ericsson.com> took at look at it and said <quote> The compressed data begins with a zlib header which seems to be two bytes containing the compression method, window size and check byte. The zlib default is a 32k window. </quote>