The internal mptopdf converter in MkIV omit some glyphs in the labels. Here's a minimal example (test.tex): \starttext \externalfigure[testfig.1][frame=on] \blank \externalfigure[testfig-1.pdf][frame=on] \stoptext And testfig.1 is produced by testfig.mp beginfig(1) label(btex $\Omega$ etex, (0,0)); currentpicture := currentpicture scaled 5; endfig; end Here's testfig.1 to save a step in debugging: %!PS %%BoundingBox: -18 -18 18 18 %%HiResBoundingBox: -17.98805 -17.0195 17.98798 17.0195 %%Creator: MetaPost 1.803 %%CreationDate: 2013.08.09:1612 %%Pages: 1 %*Font: cmr10 49.81323 9.96265 0a:8 %%BeginProlog %%EndProlog %%Page: 1 1 0 0 0 setrgbcolor -17.98805 -17.0195 moveto (\012) cmr10 49.81323 fshow showpage %%EOF Then do: mptopdf testfig.1 context test.tex xpdf test.pdf The first framed box, using the internal mps->pdf conversion, is empty. The second framed go, using the pdf file produced by mptopdf, correctly contains \Omega. With \enabletrackers[graphics.conversion,graphics.inclusion], the log has the following lines, none of which seem to pinpoint the problem: graphics > inclusion > checking conversion of 'testfig.1', fullname 'testfig.1', old format 'mps', new format 'pdf', conversion 'default', resolution 'default' graphics > inclusion > no converter for 'mps' to 'pdf' [MP to PDF] graphics > inclusion > checking conversion of 'testfig-1.pdf', fullname 'testfig-1.pdf', old format 'pdf', new format 'pdf', conversion 'default', resolution 'default' graphics > inclusion > no converter for 'pdf' to 'pdf' graphics > inclusion > new graphic, using hash 'testfig-1.pdf->1->crop->unknown->unknown->unknown->' (Though I don't believe the "no converter for 'mps' to 'pdf'" diagnostic.) This is with Context 2013.05.28 00:36 MKIV (TL2013 on Debian). -Sanjoy