Is it possible to approximate fake "optical sizes" with fontspec using a font which doesn't have this feature (in my case, Cambria)?

The use case here is that I'm writing a scientific text with lots of in-text \textsuperscript and \textsubscript which would really benefit from being slightly bolder.

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    The short answer is: "no" :) – Will Robertson May 8 '18 at 7:48
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    The slightly longer answer is that MAYBE with adjusting weight and width just a little you could create something that wasn't terribly ugly on first glance. – Will Robertson May 8 '18 at 7:49
  • Thanks, that's what I suspected, but for some reason I can't get a minimal working example for FakeBold with Cambria. Is this expected? – Mathieu May 8 '18 at 8:15
  • See my comment to Henri Menke's answer below: the current default macOS PDF engine fails to render FakeBold. Oh well... – Mathieu May 8 '18 at 11:56
  • Update: the PDFkit bug appears to have been fixed in the latest macOS update (10.13.4, 17E199). – Mathieu May 12 '18 at 13:07

If it is only about the super and subscript, you could redefine those macros to add boldening using PDF literals.



  \special{pdf:literal 2 Tr 1.0 w}% adjust the 1.0
  \special{pdf:literal 0 Tr 0 w}%




enter image description here

  • Wow, thanks, that solves quite nicely my original issue. On the flip side, I've discovered that macOS High Sierra's Preview.app completely fails to render your emboldened sub/superscripts as intended. The fault lies with Preview, though, not with XeLaTeX, because Adobe Reader renders everything correctly. – Mathieu May 8 '18 at 11:55
  • @Mathieu — oh, that's a real shame. I'd heard the new PDF rendering engine in macOS was a step backwards... – Will Robertson May 8 '18 at 13:38
  • Amazingly, this bug appears to have been fixed in the latest macOS update (10.13.4, 17E199). Thanks again. – Mathieu May 12 '18 at 13:06

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