From: John Hudson (tiro@tiro.com)
Date: Sun Mar 02 2003 - 21:08:46 EST
At 04:11 AM 3/2/2003, Kevin Brown wrote:
>I'm working on a Latin-based font that's got a large number of kerning
>pairs already defined and I'm trying to pare this list of pairs down to
>the bare minimum. There seem to be many pairs which are unlikely ever to
>be used. These pairs all involve a lowercase on the left with an
>uppercase on the right.
>
>My intuition is to delete all such pairs but since I am not a linguist I
>thought I'd better check first. Does anyone know of a Latin-based
>language in which it is possible to have a lowercase immediately followed
>by an uppercase in the SAME word?
This is not uncommon in some of the Bantu languages; I can't remember which 
ones, but at least one major regional language in southern Africa.
You should be aware that there are lots of applications that gag on large 
numbers of kerning pairs. Thomas Phinney in the type group at Adobe advised 
us that 3,000 standard kern pairs is about the maximum one can expect to 
work in all apps. Some applications will fail to support the rull range of 
kerning pairs if there are too many; some applications will not support any 
kerning if there are too many pairs; and some older applications may even 
crash.
In OpenType fonts, using GPOS instead of kern table kerning, you can employ 
class-based kerning, which can be very handy for large fonts. Some systems 
will decompile GPOS kerning to standard kerning on the fly, which may 
result in subsetting of kerning (Adobe Type Manager and the CFF rasteriser 
in Windows does this for PS-flavour OT fonts, subsetting to Windows CP 1252 
support). The subsetting is necessary because the fully decompiled 
class-based kerning for a font can easily overload many applications (the 
class-based kerning in Adobe's Minion Pro decompiles to approx. 70,000 
pairs). Adobe's latest applications, e.g. InDesign, make direct use of GPOS 
kerning, so can access all the kerning in a font. Hopefully more 
applications and systems will soon follow suit. Windows supports GPOS 
kerning for complex scripts via Uniscribe, but not yet for Latin or other 
'simple' scripts.
Finally, bear in mind that an excessive number of kerning pairs may 
indicate that your font has fundamental spacing problems. It is often 
possible to reduce the number of kerning pairs by revising the sidebearings 
to produce a better pre-kern fit.
John Hudson
Tiro Typeworks		www.tiro.com
Vancouver, BC		tiro@tiro.com
It is necessary that by all means and cunning,
the cursed owners of books should be persuaded
to make them available to us, either by argument
or by force.      - Michael Apostolis, 1467
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