Verity Image Format (VIF) is a bi-level raster graphics format associated with a search-related product called Topic, developed by Verity, Inc.
It reportedly uses CCITT Group 4 compression. It appears to have a header consisting of ASCII-encoded decimal digits.
See Verity for related formats.
Verity's web site was at www.verity.com, but the available archives of it seem to make no mention of Topic.