Tue 28 Dec 2010 08:36:01 PM UTC, comment #5:
> The question to answer in the first place is: In a multiline
> text, how does one determine the "correct" (desired by the font
> designer) top and bottom spacing from the bounding box, the
> ascender and the descender?
The following can be found in the TrueType specification; this is fully valid for Type 1 fonts also:
"sTypoAscender is used to determine the optimum offset from
the top of a text frame to the first baseline.
sTypoDescender is used to determine the optimum offset from
the last baseline to the bottom of the text frame. The value
of (sTypoAscender - sTypoDescender) is recommended to equal
one em. [...]
For Western fonts, the `Ascender' and `Descender' fields in
Type 1 fonts' AFM files are a good source of `sTypoAscender'
and `sTypoDescender', respectively. The Minion Pro font
family (designed on a 1000-unit em), for example, sets
sTypoAscender = 727 and sTypoDescender = -273.
`sTypoAscender', `sTypoDescender' and `sTypoLineGap' specify
the recommended line spacing for single-spaced horizontal
text. The baseline-to-baseline value is expressed by:
OS/2.sTypoAscender - OS/2.sTypoDescender + OS/2.sTypoLineGap
`sTypoLineGap' will usually be set by the font developer such
that the value of the above expression is approximately 120%
of the em. The application can use this value as the default
horizontal line spacing. The Minion Pro font family
(designed on a 1000-unit em), for example, sets sTypoLineGap
= 200."
Does this answer your question? Note that Type 1 fonts don't have something equal to `sTypoLineGap'; TeX, for example, uses 120% by default, but most books use a larger value (e.g. 130%) which increases readability.
Not having the Frutiger PFB/AFM files, I can only say that `unpatched.png' looks much better to me.
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