[NO BUG] Kerning Questions

[Dick Pape]

The kerning calculation is peculiar.

For most pairs, the result seems far too tight as if there is 0 distance (or perhaps 10) between two letters. For certain punctuation, it uses the white space value as the absolute distance. It is shown in the kerning dialog picture.

I used Autometrics and Autokerning. For Autokerning I: Selected glyphs, set "White spaces between characters" as 100 and "Minimum absolute kerning value" as 10.

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AWT Page Antique XX Cond.fcp

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This inconsistency is not understood. Can you help?

Checking further, this seems to be evident in Vn 6.5 ...

[vanisaac]

Autokerning normalizes the horizontal distance between the closest parts of the two characters. When two characters do not occupy any of the same horizontal space, there is no horizontal distance between the characters to calculate, so it just puts in the default spacing between the two characters, because it doesn't have any other information to go on.

[Dick Pape]

Then seeing how this font was inconsistently aligned, autokerning is worthless.

I normally don't use autokerning, so this is a new curve for me to understand.

[vanisaac]

No, autokerning worked just fine for all of the character combinations where there was a horizontal distance to calculate, like "( and "". Each of those got a nice autokern. It just doesn't work for things like ", or -.

[Dick Pape]

Yea, but, if you select "Import kerning pairs from file" it doesn't do that.

[Bhikkhu Pesala]

Yea, but, if you select "Import kerning pairs from file" it doesn't do that.

Well, or course not. It's using fixed values saved in the text file, not calculating variable values determined by the shape of the pairs in the glyph.

It depends on the font, but a value of 100 funits for white spacing is probably not enough — the default is 350, and 10 funits is too small a value for a minimum (default is 50). There's hardly any point having a kerning pair with such a low value (assuming that you're using 2048 funits per em).