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Open Type
The next big thing or hyped up type?
By Malcolm Wooden, DTPTypes
As
a user of fonts, you must have heard of OpenType by now. But do you
know the impact it's likely to have on your business. When I ask my
clients and other users if they plan to use OpenType, they generally
respond by asking me three fundamental questions in return:
- What is it and how does it work?
- Will it be of benefit to my way of work?
- Can I use OpenType now for some of my clients' projects?
Ok,
lets try and answer these three questions and look at the overall
strategy of OpenType fonts. The answers are not all straight forward,
and apply in differing degrees according to your type of work and
production procedures.
What is OpenType?
Here's
the technical bit. OpenType is an extension of the TrueType font format
originally developed by Apple Computer and Microsoft back in the early
1980's to compete with the Adobe Type1 font format. One of the
extensions to TrueType has been the introduction by Adobe of PostScript
font data into the format as CFF data.
PostScript CFF
The
structure of TrueType differs from that of Type1 in that it is based
around tables of data. Each font is a mini database of information. The
format comprises of a 'Table Directory' holding information of what
tables are in the font and where in the font file the tables can be
found. Most TrueType fonts contain about 15 to 18 tables (depending on
the type of font and the manufacturer), and only one table contains the
information describing the outline data of the font glyphs or
characters. It is this table that in OpenType can be either PostScript
CFF data or TrueType glyph data, but as a user, being PostScript or
TrueType will not make any difference to you using the font, the
difference will be in the quality of the OpenType data from the font
manufacturer.
Ok, so OpenType can be TrueType based or
PostScript based - is that all? Well no, that's just the beginning.
What really makes a font OpenType are two basic criteria. Unicode and
Advanced Typography Features.
Unicode
If you use
Macintosh computers, you will know that the basic character set for a
Mac is called 'MacRoman'. There are other character sets defined by
Apple for different regions of the world (MacGreek, MacCyrillic,
MacCentralEuropean etc). MacRoman can contain no more that 256
characters (1byte, 8bits, or 16 x 16), 35 of these characters have to
be control characters (tab, return and word spaces etc), so the maximum
number of characters in a Mac font cannot exceed 221.
Unicode however is not restricted to one
byte coding, it's an evolving code system that aims to cover as many
scripts, languages and dialects as is applicable. At present Unicode is
based on two bytes to define character code points (2byte = 16bits, 256
x 256 or 65,536 codes), so a single font can contain characters for
east and west European languages, Greek, Cyrillic, Hebrew, Arabic...
etc. For more information on The Unicode Standard, go to www.unicode.org
Advanced Typography Features
From
the page design and typographical viewpoint, the advanced typographical
features that are part of OpenType will be of great importance,
bringing a level of 'intelligence' to fonts that will mean the end of
'Expert Sets' and other font variants. OpenType fonts control the
features by sets of substitution (GSUB) and repositioning (GPOS)
tables. As a simple example, a font may have a different design of
lowercase 's' for use as a final letter in a word, e.g.
'surreptitious'. The underlying code of the document will only create
coding for the characters in word. The code in the GSUB table ofthe
font will tell the application to replace the last 's' in the word with
the special 'final s' form in the font. The basic coding of the
document has not been compromised, but the page typography has been
enhanced by the addition of the correct typographical elements, without
the need for an additional font.
OpenType fonts can now contain many
variations of a single character; in fact there has been a move in the
font developers vocabulary away from describing a single letter design
a 'character' to calling it a 'glyph'. Advanced Typography features
will mean that a font could contain a dozen different designs of the
ampersand '&' (for example). The underlying code of the document
will describe an ampersand character, but the OpenType font will use
the appropriate glyph to represent the ampersand depending on how the
variants have been defined (e.g. three-quarter size ampersand or
isolated ampersand or large swash ampersand etc.
The sample above shows how typography
can be improved with OpenType features. Top line shows some plain type
while the bottom line shows initial and final lowercase glyphs and
alternate capitals.
The power in OpenType Features will be
more widely applicable to foreign=language scripts, such as Arabic and
the Indic language scripts, but our own humble Latin script has lost
much of it's fineness over the decades=because of the mechanical
restrictions forced onto printers limiting the numbers of letter forms.
OpenType could well be the start of a revival of a more pure
typographical form.
What are the benefits?
Many
of the typographical benefits can be seen from what has been described
above. One other major benefit is that with OpenType there is a single
font file that will 'work' on either a Macintosh computer or a
Microsoft Windows PC. No more printer font/screen font problems.
OpenType fonts will install in the same way as previous font formats -
install into 'font' directory locations or handled by a font 'manager'
e.g. ATM. Documents that are created using TrueType should be more
transportable, no more missing or changed characters when moving
documents from Windows to Mac
The Unicode based coding of characters
will bring about much better language support. East European, Cyrillic
and Greek will work especially well, however right to left reading
languages will probably still need extra application or system support.
No more Expert Sets or supplemental
fonts as all character glyphs can be placed in a single font. Oldstyle
figures, true small caps, ligatures, fractions and additional accented
characters - all in a single font and accessed either automatically or
selectable from a character pallet.
Customised support can be included if
you have your own corporate font, for example a GSUB table could be
created in your fonts so that whenever your company name is keyed
between angled brackets thus the company logo would be substituted
automatically.
Can I use OpenType fonts now?
The
short answer is yes. But to get full functionality from an OpenType
font requires you to use applications that understand OpenType. If you
do not have applications that understand OpenType, then your fonts will
work as a plain non-OpenType font.
The main provider developing OpenType
applications at present is Adobe, and their flagship application
InDesign 1.5 handles OpenType fonts well, but is limited in the number
of advanced typography features it supports. Other Adobe applications
are coming online but are limited at present. Adobe have played a big
part in championing this technology, and you can expect their
applications to gradually start supporting OpenType, and the
integration of OpenType handling between their applications.
Microsoft are also building their
Windows system and many of their applications with OpenType support,
particularly on building foreign language support like Hebrew and
Arabic.
Apple are being more reticent about
supporting OpenType directly. They are producing a parallel system
called ATSUI (Apple Type Services for Unicode Imaging) for supporting
Unicode and AAT (Apple Advanced Typography) for supporting advanced
typographical features, but third party application support for this
technology is not yet available
How will OpenType work on today's systems?
Fonts
are basic system resources, so if the system cannot support OpenType,
nor will most of the applications. An exception to this is Adobe, who
have developed a whole sub-system called 'CoolType' to circumvent much
of the native operating system.
Support for OpenType is a two-part
thing. The operating system needs to understand the Unicode method of
glyph coding; this can then be picked up and used by the application
program. Secondly, the application needs to understand the advanced
typography feature tables built into the OpenType fonts and implement
the required repositioning and substitution of glyphs.
The latest version of Microsoft Windows
2000 has excellent Unicode support, and can also recognise OpenType
fonts, giving them a unique OpenType icon. With Adobe InDesign 1.5
running on Windows 2000, east and west European documents, Cyrillic
(Russian) documents and Greek created in Microsoft Word can be imported
directly into InDesign and, where applicable, the advanced typographic
features will drop into place. Accessing foreign language text is done
through the Windows keyboard layout settings, changing to the Greek
keyboard (for example) will give access to the Greek characters of the
OpenType font.
Apple Macintosh computers are not so
advanced with support for OpenType. Unicode support with keyboard
switching has yet to be made available and Adobe's InDesign application
relies on CoolType to do much of the work.
The number of fonts available at present
is also limited. Adobe offer a range of OpenType fonts but at present
they are not available outside of U.S.A. Microsoft's OpenType fonts do
not have any Latin based advanced typographical features yet.
The DTP Types library is making available a range of OpenType fonts with advanced typographical features such as:
- True Small Capitals
- Oldstyle Figures
- Full range of ligatures
- A glyph complement of over 650.
See samples of these fonts here: Berstromand Delargo DT Informal.
More fonts with Cyrillic and Greek language support will be following shortly.
OpenType is still very young, and who knows where
it may go, but with the likes of Adobe and Microsoft behind it, it is
unlikely to fade away as did Apple's GX technology, and because of the
extendable nature of the OpenType font format, much is yet be added.
It's not the end of the old Type1 format just yet though. You should
still hang on to those printer font and screen font collections for a
little while longer.
