Take a look at this picture:

Central stroke in a glyph

The red lines inside a glyph is what I'm referring to as "central" or "pen" strokes. Imagine you drawing the letter using a pen, so you only have thin strokes which define a general shape of a letter instead of wider inked areas which font glyphs typically have.

  1. What is the proper name of this type of strokes? I've looked through a lot of "font anatomy" illustrations, and none of them mention this.

  2. Are these lines used in font design? Maybe when you create a digital font, you could start with those strokes and then add modulation. For fonts like Comic Sans it may be even sufficient to just use these strokes with proper line width.

  3. If the answer for the previous question is "yes", do any font formats store this information along with glyphs? If they do, what it's used for? I guess, for some fonts this can be used to dynamically create glyphs with different thickness.

2 Answers 2


1. What is the proper name of this type of strokes?

The line itself would be called the centerline. There may be other or better terms depending on the context but that's what I would call it.

2. Are these lines used in font design?

It depends. They certainly could be, but not necessarily.

3. do any font formats store this information along with glyphs?

Generally no, but they exist. Monoline or single-line fonts as they are called are useful for things like engraving and laser cutting (so you only get one continuous pass on each glyph).

You can find a selection of single-line fonts here: http://imajeenyus.com/computer/20150110_single_line_fonts/index.shtml

If you want the get the centerline from a regular font there are a number of previous questions with techniques:

There is a script for Illustrator that was posted on the Adobe Forums that may be of help (it was written for CS4, but apparently works up to CS6, not sure about other versions):

  • Thank you for additional links. I do want to extract centerlines from some opensource fonts, so these links are very useful.
    – scriptin
    Commented Jun 4, 2016 at 12:27
  • No problem. If you're working with a relatively short string of text it's not too hard but if you're working with a lot of copy I would just try and find a monoline font to begin with.
    – Cai
    Commented Jun 4, 2016 at 13:20
  • I'm looking for a CJK font and, unfortunately, there's not a whole lot of options.
    – scriptin
    Commented Jun 4, 2016 at 16:57

This is more of a long comment:

  1. I dont know about proper in this context, but in more scientific literature ive seen it called straight skeleton.

  2. Sometimes.

  3. It is not really possible to do this with our currenr main font technology without cheating. But it is possible to do in now obsolete postscript fonts. Further there is a chance that you can again once the color font standards move ahead (so our font tech has finaly made a full 360 degree revolution).

  • Thank you. I've already read your answer on one of the linked questions. Yes, straight skeleton or medial axis are two possible ways to go. Both would require some additional filtering and post-processing, but it's a good start.
    – scriptin
    Commented Jun 4, 2016 at 17:06

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