PBMtoPK and PKtoPBM are on the Aston archive, in the directory [tex-archive.fonts.duggan].
PBMtoPK was posted to Usenet group alt.sources at the beginning of August, with three patches on 10th
August, 12th August, and 21st September, and
so should be available from any archive storing alt.sources.
(Walnut Creek)(1995).ISO/graphics/pbmtopk/doc/pbmtopk.tex/img4.png)
.