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charlesk97504850
charlesk97504850
Participant
July 20, 2022
Question

Does a kerning pair become a glyph?

  • July 20, 2022
  • 2 replies
  • 732 views

In diagnosing a pink highlighted line with a "box" symbol outside the right margin, I discovered the following.

Word division of "qualification" caused the error. The letter pair "ic" has a value of -20 applied manually. The box and pink highlight will disapear if one of two things are done. 1. Remove the kerning value for "ic".   2. Turning off ligatures for "fi". 

 

Is this error occuring because Indesign considers the kerned pair "ic" to be a glyph, which becomes "missing" when the pair is divided at the end of a line? Or is the combination of a ligature pair sharing a character with a kerned pair that becomes broken an issue for some reason?    The box symbol carrries over in a PDF generated from the ID file.

This topic has been closed for replies.

2 replies

L
Community Expert
LaubenderCommunity Expert
Community Expert
July 21, 2022

Hi @charlesk97504850 ,

could you share a sample InDesign document with the issue?

One page with one text frame is sufficient to see into the case.

 

What is the font you are using?

What paragraph composer is applied to the text?

 

Thanks,
Uwe Laubender
( Adobe Community Professional )

charlesk97504850
charlesk97504850Author
Participant
July 21, 2022
Uwe, Here is the doc. This issue also occurs with fl ligature. Word division of a manually kerned pair does not generate an error unless the first character is part of a ligature.

In this document Stempel Garamond LT Std. is used, but most fonts will replicate this issue if they have ligatures available.

Single composer was used, but additional samples I provided in document have an example in para-composer mode.

Seems to me that the first letter of the kerned pair is losing its “identity” when it becomes morphed into a ligature while simultaneously having to separate (word division) from the following letter it is manually kerned with. The letter “i” in this case is having to choose between two identities. Am I a ligature or the first character in a kerned pair? Thus my query as to what constitutes a glyph. Has to be some reason the software considers something to be “missing” under these conditions?


Charlie
L
Community Expert
LaubenderCommunity Expert
Community Expert
July 21, 2022

"Uwe, Here is the doc. "

 

Hi Charlie,

sorry, but obviously something went wrong. I cannot see an attachement on your post.

 

Note: you have to use the forum editor to attach files.

Attachment with a mail reply will not work at all.

 

Regards,
Uwe Laubender
( Adobe Community Professional )

Bevi Chagnon - PubCom.com
Bevi Chagnon - PubCom.com
Legend
July 20, 2022

First, a "kerning pair" is an automated algorithm built into the font or manually set in InDesign to adjust the amount of space between the letters.  Kerning does not create a new character of glyph. It only controls the letter spacing.

See https://helpx.adobe.com/indesign/using/kerning-tracking.html  for more details.

 

Ligatures are when two letters are combined to form a single ligature glyph, such as the f and i in your sample being combined into one ligature "fi".  Zoom in closely on those letters in your sample and you can see that the i's dot is removed so that it doesn't combined with the arched "arm" of the f.

 

quote

Is this error occuring because Indesign considers the kerned pair "ic" to be a glyph, which becomes "missing" when the pair is divided at the end of a line? Or is the combination of a ligature pair sharing a character with a kerned pair that becomes broken an issue for some reason?    The box symbol carrries over in a PDF generated from the ID file.

By @charlesk97504850

 

"ic" isn't a ligature glyph.

And I don't think either is causing the box error.

I think that InDesign's hyphenation algorithm is getting thrown off by the ligature preceeding the hyphenation point. I don't know why, as I've never seen ligatures affect hyphenation this way.

 

But turn off ligatures either for just that word or in your paragraph styles.

 

Maybe someone else can shed some light on this.

 

|    Bevi Chagnon   |  Designer, Trainer, & Technologist for Accessible Documents ||    PubCom |    Classes & Books for Accessible InDesign, PDFs & MS Office |
James Gifford—NitroPress
James Gifford—NitroPress
Legend
July 21, 2022

AFAIK — some from experience with other systems — ligatures are a "display level only" effect. In all other ways, the app treats them as individual letters (for search, for language management, for hyphenation, etc.) and only replaces the letters with a different display/print glyph at a separate level.

 

What this means for the OP is not clear, but ligatures shouldn't affect any text-level management or processing.

 

—

    Bevi Chagnon - PubCom.com
    Bevi Chagnon - PubCom.com
    Legend
    July 21, 2022

    That's what I learned, too.

    However, being in the accessible document field, we sometimes run into problems with ligatures not being voiced or recognized by some screen reader software (used by those who are blind or have low vision).

     

    These common ligatures are built into the Unicode character encoding system and rarely pose a problem, as long as a Unicode/OpenType font is used rather than PostScript and old ASCII Truetype:

    • FB00 ff LATIN SMALL LIGATURE ff
    • FB01 fi LATIN SMALL LIGATURE fi
    • FB02 fl LATIN SMALL LIGATURE fl
    • FB03 ffi LATIN SMALL LIGATURE ffi
    • FB04 ffl LATIN SMALL LIGATURE ffl
    • FB05 ſt LATIN SMALL LIGATURE LONG ft
    • FB06 st LATIN SMALL LIGATURE st

     

    Of course, some fonts don't have these ligatures, and other fonts contain more ligatures.

     

    |    Bevi Chagnon   |  Designer, Trainer, & Technologist for Accessible Documents ||    PubCom |    Classes & Books for Accessible InDesign, PDFs & MS Office |
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