Re: ascender, descender, cap-height and x-height

Erik van der Poel wrote:
> 
> Jelle Bosma wrote:
> >
> > It is the type designer who decides on how large the font
> > is in the EM square. There are no rules. In TrueType
> > (and OpenType) you can get some measurements such
> > as the Typographic ascend and descend as explained by Greg.
> > These values are in the OS/2 table of the font.
> > In Monotype fonts these are set to top f and bottom g
> > for the font family. Whether fonts of other foundries
> > contain reliable values I am not sure. Many foundries didn't
> > bother much about these things until recently.
> 
> Do you also happen to know why those "many" foundries are now more
> concerned about these things? I'd really like to know.

Because previously, type was set by a designer, by eye, and what they saw
then got written to film and used to make plates and what was printed was
what the designer saw (modulo factors such as dot gain and ink fill-ins on
traps and paper stretch and so on, which a good designer would work around
anyway).

Nowadays, type is frequently set by computer, and computers have no common
sense or design ability whatsoever but must mechanically follow rules. And
type is frequently specified on one computer but expected to work on
heterogenous platforms with different settings for pixel density, font
rasterisation algorithm, availability of anti-aliasing, different gamma,
different fonts (or different revisions of those fonts) and thus, the
optional extra information - which basically didn't do anything very
practical before apart from being there for completeness - is being
depended upon, has an effect,and therefore thre is precedent and reason to
put it in.

> The reason I'm concerned is because the Internet has caused many
> different platforms and many different document types to come into
> direct contact.

Exactly. The Web is a heterogenous distributed computing environment, and
that environment places different demands on type to the demands of a more
traditional, paper-oriented, homgeneous output environment. Thus, type has
adapted, as it always adapts, to the ways in which it is being used.

--
Chris

Received on Thursday, 27 January 2000 15:44:39 UTC