metrics in InDesign different than in FontForge

samueldurt
samueldurt Posts: 4
in Font Technology

Bonjour, 

Thank you for lettin' me in. I found this website while I was looking for an answer to this question: how come metrics differ between a design program and a layout program? And how can we fix it? I just made my 1st font with Font Forge. And when I test it in InDesign, the metrics are different than the ones I defined in Font Forge. It's a bit better if I export the font in true type instead of open type... but it's still different. Please find hereabove an illustration:
- in black (and behind), the metrics in Font Forge,
- in yellow, the font used in InDesign (got exported as a true type),
- and in magenta (on top) the font used in InDesign but exported as an open type.

Thank you!

Kind regards,
Samuel Durt

Comments

  • John Hudson
    John Hudson Posts: 3,229
    First thing to check: in InDesign, is kerning set to Metrics or to Optical? If it were set to Optical, you would get autokerning that would override font spacing. [And no, I don't know whether that would explain the difference between TTF and CFF fonts, but it is the first thing to rule out when talking about spacing in InDesign.]
  • samueldurt
    samueldurt Posts: 4
    I let 'metrics' in InDesign.
  • John Hudson
    John Hudson Posts: 3,229
    Hmm.

    Okay, next step would be to check the metrics of the compiled fonts to the metrics of your source. I would try to do this using a different tool than the one you use to generate the font, i.e. don’t just open the OTF or TTF in the same design tool as your source. Ideally, use something like OTMaster, so you can check the actual binary data.

    This step is to confirm that the issue is not due to a problem in the font generation, rather than a problem in InDesign.
  • Chris Lozos
    Chris Lozos Posts: 1,458
    What OPM did you use? For anything different than 1000, ID will round your values to what you would expect for 1000. A kern of 32 units in a font drawn at 2048 would show as about 15 after rounding.
  • Thomas Phinney
    Thomas Phinney Posts: 2,898
    Although what Chris writes is entirely correct... that should only affect InDesign’s display of the kerning, and at worst introduce pretty much invisible rounding error. It shouldn’t be possible to create the kinds of differences shown in the screen shot from this effect.
  • Jens Kutilek
    Jens Kutilek Posts: 364
    Does FontForge do different things when exporting an OTF vs TTF? Maybe there is a kern table in the TTF and no GPOS kern feature? Just guessing …
  • samueldurt
    samueldurt Posts: 4
    Hello,

    Sorry, I had not noticed that there were answers.
    Maybe I should share it.
  • samueldurt
    samueldurt Posts: 4
    edited May 2021
    Doesn't work... File format not allowed. OK.
    Does OPM mean EM? Then it's 1000 indeed. For the OTF. I changed it for the True Type.
  • Dave Crossland
    Dave Crossland Posts: 1,431
    You don't need to change it for the TTF any more :) 
  • John Hudson
    John Hudson Posts: 3,229
    You don't need to change it for the TTF any more

    Or ever. TrueType has always been able to have arbitrary UPM.

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