Automatic italic correction? (plain TeX)

Peter

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May 30, 2002, 5:41:29 PM5/30/02

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I've been using LaTeX for a few years now but mostly in a very minimal
way. Recently I've started getting into it more (and I'm having fun). I
started reading over Knuth's "The TeXbook" to get a better understand of
the TeX system in general.

Anyway, in one of the earlier chapters Knuth talks a bit about italic
correction. For instance

This is the {\it second\/} thing.

The idea being that you want a little extra space after the italic 'd'
so that it doesn't crowd the 't' in "thing". Knuth mentions that you
don't want this correction if the italicized text ends with a period or
a comma. That makes sense. My question is, though, why doesn't TeX
handle this automatically? After all, it automatically selects ligatures
and I get the impression that it automatically handles kerning. Is there
some subtle reason why human intervention is needed to deal with the
italic correction issue?

Peter

David Kastrup

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May 30, 2002, 6:46:40 PM5/30/02

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Peter <p...@ecet.vtc.edu> writes:

It's sometimes subject to judicious decision. Anyhow, LaTeX with its
\emph and \textsl and similar environments _does_ automatic correction.

--
David Kastrup, Kriemhildstr. 15, 44793 Bochum
Email: David....@t-online.de

Heiko Oberdiek

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May 30, 2002, 9:57:32 PM5/30/02

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Peter <p...@ecet.vtc.edu> wrote:

> I've been using LaTeX for a few years now but mostly in a very minimal
> way. Recently I've started getting into it more (and I'm having fun). I
> started reading over Knuth's "The TeXbook" to get a better understand of
> the TeX system in general.
>
> Anyway, in one of the earlier chapters Knuth talks a bit about italic
> correction. For instance
>
> This is the {\it second\/} thing.
>
> The idea being that you want a little extra space after the italic 'd'
> so that it doesn't crowd the 't' in "thing". Knuth mentions that you
> don't want this correction if the italicized text ends with a period or
> a comma. That makes sense. My question is, though, why doesn't TeX
> handle this automatically?

That's the difference between plain TeX and LaTeX:
\This is the \textit{second} thing.
No italics correction \textit{here}.

Yours sincerely
Heiko <ober...@uni-freiburg.de>

Donald Arseneau

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May 30, 2002, 11:18:47 PM5/30/02

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Peter <p...@ecet.vtc.edu> writes:

> a comma. That makes sense. My question is, though, why doesn't TeX

> handle [italic correction] automatically? After all, it automatically

> selects ligatures and I get the impression that it automatically handles
> kerning. Is there some subtle reason why human intervention is needed to
> deal with the italic correction issue?

Not so subtle. TeX does kerning and ligatures between characters
in the same font because the information to do so is given by
the "font metrics". TeX doesn't know the actual shape of the
characters it uses, so it can't invent kerning between different
fonts. (This and hyphenation are the serious drawback to TeX's
limited 256-character limit for fonts.)

Donald Arseneau as...@triumf.ca

Peter

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May 31, 2002, 7:04:56 AM5/31/02

to

In article <ad6l3k$r2h$3...@n.ruf.uni-freiburg.de>, oberdiek@uni-
freiburg.de says...

> That's the difference between plain TeX and LaTeX:
> \This is the \textit{second} thing.
> No italics correction \textit{here}.

Okay, cool. Thanks for the clarification.

Peter

Dan Luecking

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May 31, 2002, 12:48:53 PM5/31/02

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Search google with italic correction automatically group:comp.text.tex
and read the 27 followups on the same subject from February 2002.

Dan

Dan Luecking
Department of Mathematical Sciences
University of Arkansas
Fayetteville, Arkansas 72701