The PostScript page
description language was developed by Adobe and became a major
force when Apple adopted PostScript for its Apple LaserWriter
printer in 1985. The popularity of PostScript grew over the next
few years as it was adopted by many graphics programs as well
as high end imagesetting devices.
To compliment the
PostScript page description language Adobe developed two PostScript
font formats, entitled Type 1 and Type 3. The file format specification
for Type 3 was published, but due to the fact that Type 3 fonts
did not render well on low resolution devices, the format never
became popular. Adobe decided at that time, not to publish the
Type 1 specification and it was this decision that ultimately
caused Apple to develop the TrueType font format.
In 1990, Adobe finally
released the Type 1 font format, but by then Apple and Microsoft
had collaborated on the TrueType project and both companies were
to soon release operating systems with native support for TrueType.
From this point onwards TrueType was to establish itself as the
font format of choice for most desktop computer users.
The PostScript Type
1 font format is a digital, outline font format that supports
hinting. A description which can also be applied to the TrueType
font format. Indeed both formats share some common attributes.
Both enable any character to be scaled to any size without loss
of quality and both formats support hinting, a technology which
improves legibility of characters at low resolutions.
the font formats are quite different. Although both formats store
the character outlines as mathematical definitions, TrueType
uses quadratic B-splines, whereas PostScript uses cubic bézier
curves. Although supporters of both formats may offer benefits
of their preferred format, neither offer any real significant
advantage to the user.
The other main difference,
which does produce a significant advantage to the user, lies
in the area of hinting. PostScript compared to TrueType has a
very limited amount of control over the final displayed image.
Both implementations of hinting will improve the display of characters
on low resolution devices, but a well hinted TrueType font will
produce significantly better images. Click
here for more information regarding TrueType hinting.
The obvious question
at this point must be "why do people still use PostScript
fonts?". There appear to be no real benefits and indeed
the reasons tend to be historically based. Firstly, because the
PostScript format was established before TrueType, most type
foundries have produced their fonts using the PostScript format
and it is only in recent years that they have started to produce
larger numbers of TrueType fonts. Therefore if a particular font
is required it may not always be available in a TrueType format.
The other reason
relates to imagesetting, the high end printing process used by
many commercial printers. Almost all imagesetting devices use
the PostScript language and historically many devices have been
problematic when used with TrueType fonts. For this reason designers
tend to use PostScript fonts rather than TrueType fonts to ensure
compatibility with their commercial printers output devices.
This problem has essentially now been resolved with new software
and newer imagesetting devices and slowly the trend is changing
in this area to use TrueType fonts.
to Technology page