YBM

This article describes the uncompressed bi-level image format that is usually called something like Bennet Yee's face format, and sometimes YBM. It does not seem to have an official name. It is the format used by Netpbm's ybmtopbm/pbmtoybm utilities, and is among the formats supported by the Fuzzy Pixmap library ( option). It originated with utilities named "face" and "xbm", by Bennet Yee.

Disambiguation
The name "Bennet Yee's face format" has also been used when referring to FaceSaver, a completely different format. This may or may not be an error.

Format
Files have a 6-byte header, followed by the image data.

Identifiers
The Fuzzy Pixmap library suggests the file extension .bm.

Identification
Files begin with  (ASCII " ").

Software

 * Netpbm: pbmtoybm, ybmtopbm
 * fbm-1.2.tgz - Fuzzy Pixmap Manipulation Library (see also FBM image)

Editors' notes
It would be nice to find copies of the "face" and "xbm" utilities. They are referenced in the man pages of old versions of Netpbm, which suggests that they were publicly available.