OpenType fonts
OpenType data structure
Technically an OpenType font is a combination of outline data (in either PostScript or TrueType format, as noted above) and other data that are organized in a series of tables. These tables contain the following information:
- The header includes general information such as the file name, version, creation and modification date and data on the coordinate system.
- The character to glyph mapping table (CMAP) documents the relation between characters and character shapes (glyphs). It supports:
- traditional ISO encodings
- encodings from Adobe and Apple
- Unicode encoding.
- The naming table defines the name of the font, the family it belongs to and the type of font.
- Another table contains the actual outline data (glyphs).
- When these are PostScript font data, they are included in a ‘cff’ table. In this case, type 2 data are used which is a more compact and faster evolution of the well known type 1font format.
- For character shapes that are defined using TrueType format, a ‘glyf’ table is used.
- Advanced Typographic Tables contain needed data to support the extra typographic features that OpenType offers.
- OpenType fonts can also contain bitmap fonts. These are sometimes used for very complex glyphs or for very small type sizes. Bitmap font data are contained in 3 ‘bitmap glyphs’ tables.
- A ‘digital signature table’ contains a digital signature from the original creator which can be used to check whether the font has been modified.
Not all of these tables have to be present in a font and that typographers can decide themselves how much work they put in the support for all the advanced features that OpenType offers. As such, the format itself is no guarantee that you get a complete Unicode-character set or a complete set of liguratures.
8 July 2010
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Hi Laurens,
How could we embed OT fonts in PDF?… I’m trying to use OT fonts in Indesign CS4 producing PDF 1.6 and 1.7 and the resulting embedded font in the PDF is always Type 1 or TT… I would like to achieve real OT embedding to test if a preflight detects it or not…
Might I use an special kind of OT faces or something similar?
Thanks in advanced!
Best regards,
Alex
As far as I know you cannot embed OpenType fonts as OpenType when exporting directly to PDF from InDesign.
Try this instead:
- Print your document to a PostScript file without embedding any fonts.
- In the Acrobat Distiller settings, make sure the option to embed OpenType is activated and that no subsetting takes place. Set the PDF level to 1.7.
- Distill your PostScript file.
You should now have a PDF with OpenType embedded as OpenType – at least that is what PitStop preflight reports.
Just in time!
All right! Laurens, my problem was solved thanks to you. I didn’t think in Postscript + Distiller to reproduce the OT embedding. Thanks!
I can embed a Type 1 font (Myriad Pro Regular) following your instructions, but I can’t do that with an TrueType OT font like Lucida Console.
((Unfortunately) I’m working on Windows Vista now.)
Thanks a lot!
Alex
I just had w7 installed and all my type seems smaller now. Is there a way to change to larger type. Thanks
Go to the control panels and select the ‘Display’ control panel. It has an option to change the default text size. Mine is set to 120% because text is also too tiny on my Dell portable.