and had a native hinting structure (of which see
It rapidly became obvious to the major system
soware creators (Apple, Microso, and later IBM)that it was important to have scaleable font technol-
ogy supported at the level of the operating systemitself. is would allow much better screen display,compared to pre-made bitmaps which would only
look good at a few sizes, and would be jagged at allothers. So in the late s, Apple developed its own
scaleable font technology, rst code-named Royal,
and later introduced as TrueType.
Apple traded the technology to Microso in
exchange for the latter’s TrueImage PostScript clonetechnology (which was buggy at the time, and never
used by Apple, although it has surfaced in various
later incarnations). e TrueType specications were
made public, and TrueType was built into the next
versions of the Mac and Windows® operating sys-
tems, released in .
Adobe’s response started with the release of thelong-protected specications for the PostScript
Type font format in March . is was followed
by introduction of Adobe Type Manager® (ATM®)soware in mid-. ATM scales PostScript Type fonts for screen display, and for imaging on non-
PostScript printers.In early , TrueType for the Mac became avail-
able, followed by the Windows . implementation
(the Windows scaler was and remains slightly more
accurate/ecient than the Mac version, though it’s
nothing a normal user is likely to notice). Now, witheither TrueType or ATM, Mac users (and later Win-
dows and OS/ users) could actually see on-screen at
any size what the font output would look like.
So now there were two widely used outline font
specications, one (TrueType) built into the operat-ing systems used by most desktop computers world-wide, and the other (PostScript Type ) the de factostandard for publishing and the graphic arts.
But as time goes on, the practical dierences begin
to blur. e new OpenType format (discussed later),
supports both TrueType and PostScript outlines.Support for TrueType (via Apple’s TrueType ras-terizer) is built in to virtually all implementations
of PostScript Level , and is standard in PostScript
. Similarly, Type rasterizing technology is incor-
porated into Windows 2000, Windows XP, and MacOS X, side-by-side with TrueType and both avors
of OpenType. Indeed, Apple’s new Japanese systemfonts provided with the OS are in OpenType form,
albeit with some Mac-specic additions.
e rst dierence between TrueType and PostScript
fonts is their use of dierent sorts of mathematicsto describe their curves. OpenType fonts can have
either kind of outlines, with their respective advan-tages and disadvantages.
Some articles have said that TrueType fontsrequire more points than PostScript, or that they take longer to rasterize because the math is more
complicated. In fact, the math is simpler (quadratics
are simpler than cubics). Although a few shapes take
fewer points in TrueType than in PostScript (a per-fect circle takes twelve points in PostScript vs. eight
in TrueType), in practice the shapes in real-worldfonts all tend to take more points in TrueType, it’s
true that most fonts will end up using more pointsin TrueType, even if the kind of mathematics usedto describe the curves is simpler.
e primary advantage of TrueType over Type
fonts is the fact that TrueType has the potential for
better hinting. Mind you, PostScript Type hintshandle a lot: vertical and horizontal features, over-shoots, stem snaps, equal counters, and shallowcurves (“ex”). Several of these can have a thresh-
old pixel size at which they activate.
However, TrueType hints can do all that PostScript
can, and almost anything else, as dened by the very exible instructions of the TrueType language. is
includes controlling diagonals, and moving speciedpoints on the glyph outlines at specic arbitrary sizes
to improve legibility. is ability to move points at
a specic point size allows font production sta tohand-tune the bitmap pattern produced by the out-line at any specied size. Or at least it used to; morerecent divergences in TrueType rasterizing between
dierent players (including Apple and Microso)
make this a little more uncertain.
is dierence in hinting philosophy is really symptomatic of a larger philosophical dierence.