On 30 Nov 07, at 10:41, Michael Brady wrote:
> I mentioned on the InDesign list that the old warning about not using
> TrueType fonts is now unnecessary. Someone asked why? Well, seems
> like I don't know in any good detail, just that I have read on
> several different lists over the last several years that TrueType
> fonts aren't the bad guys they used to be.
> Does anyone have an explanation, or can point me to a source for the
> lifting of the moratorium?
Type 42 fonts as described in the Postscript Language Reference are
encapsulated Truetype fonts. They were instituted sometime in the
1990s: they're not in the Postscript Language Reference 2nd edition
(1990), neither are they mentioned in the Adobe Type 1 Font Format
manual of 1993, but they are in the 3rd edition (1999), which
documents Postscript Language Level 3.
Essentially, modern imagesetters can handle Truetype, but ones made
before, say, the mid 1990s are out to lunch. Who uses a decade old
The differences between Type 1 and Truetype are fairly subtle in
their effects and it's hard to say if one is more or less desirable
than the other.
My own opinion is that Truetype hinting is more effective than Type 1
hinting at low resolution, but Truetype delta hinting can be misused
so what you see isn't what you get. At normal printer resolutions
(even old 300 dpi Laserjets) the differences are negligible; it's
only under low resoluton on-screen conditions that Truetype's
superior hinting makes much difference.
Type 1 includes certain features such as the "flex" operator and the
blue zones (horizontal alignment zones) that are resolution sensitive
and automagically get rid of certain rasterization artifacts at low
resolutions. I do not know what, if any, equivalent factilities there
are in Truetype, but I'd be surprised if they didn't exist. It's
possible they don't and that the Truetype format assumes you will use
delta hinting to get equivalent results -- which would be more
difficult than coding a "flex" operator or blue zone.
The cubic Bezier segments used to define Type 1 character outlines
are a richer set of curves than the quadratic Beziers used by
Truetype, but at the end of the day this doesn't make much visible
difference, if any. From what I've seen of the guts of both Truetype
and Type 1 fonts, using quadratic Beziers doesn't much complicate the
expression of the character outline, perhaps because under Truetype
certain common control point geometries can be implicit.
Truetype has a much more flexible approach to character encoding than
Type 1, but Opentype may have obviated this difference.
Type 1 fonts may have an advantage in that they are very easy to
edit. There are programs for converting the highly compressed and
encoded PFB & PFA files to an expanded, human readable ASCII format
that is easy to edit — if you know what you are doing! I am not aware
of an equivalent non-graphical facility for editing Truetype fonts.
In principle, you can construct a Type 1 font from scratch using only
a text editor, then running the resultant file through the ascii-to-
PFB/PFA converter, but Type 1 fonts are sufficiently complex that
this would be an advanced form of auto-masochism, esp. given the
existence of good graphical font software.
"It's MY computer, Mr Gates. Stop trying to tell me what it will/won't do."