What is a font?
The question is not as straightforward as it might seem. The word font has
come to be a general term for everything from the software to the typeface
design. In this article, the word font is used for the software for which
a user can buy licenses and which enables a machine, like a computer or
printer, to display and/or print images of a typeface design.
(Description courtesy: Linotype.com)
What is a font family?
A font family is a group of fonts which can be linked together for convenient
use. The most common font family consists of the plain, italic, bold and
bold italic weights. The link between these four fonts on a computer enable
the use of style buttons like those in Microsoft Word, for example. When
you are writing a text using the plain defined weight of the font and would
like to emphasise something with an italic, this link allows you to just press
the ‘I’ button instead of having to choose a new font (the italic weight) from
the font menu. (Courtesy: Linotype.com)
How Mac and Windows environments organise fonts differently?
On a Windows PC all fonts which are parts of font families are treated as
such. And because this family link eliminates the need to see all members
of a font family in the font menu, a PC font menu shows only the plain font
of the family. A Mac can organise fonts by family, but unlike on a Windows
PC, they can also be organised by their individual names. You can use
the style buttons to access the different fonts in the family, but when you
choose a particular font from the folder, you can see exactly which one it is.
On a PC sometimes bold or italic looks funny when you press the
corresponding style button in their program. This is often due to the
fact that only one font weight is on the computer. Some applications
can electronically alter a plain font so that it looks like an italic or bold
version, however, this is not the same as the italic or bold font itself. The
appearance of such electronically altered fonts, both on the screen and in
a printout, can vary, and some printers will not print them at all. When you
buy the full font family, you are buying fonts which have been designed,
constructed and mastered to fit harmoniously together, both on screen and
in printouts.
Another possibly confusing fact about font families is the way they are
listed in a program’s font menu. As explained above, a font family has one
font which represents the entire family in the font menu. For example, if
you instal Frutiger 45 light on your computer, you will see Frutiger 45 light
in the font menu. If you then instal Frutiger 46 light italic, you will still only
see Frutiger 45 light in a PC font menu. On a Mac you will have both style
links and a list of all fonts in the font menu, so you would see Frutiger 46
light italic in the menu. (Not all fonts are linked in families, in which case you
would see all font names in the font menu but could not use style buttons.)
And if you first instal the family version of Frutiger 65 bold, you will also see
Frutiger 45 light in the font menu, even if you never instal the font with this
name.
Characters and Glyphs
The difference between a character and a glyph is one to keep in mind
while reading through this feature, as it is essential to understanding
Unicode. A character is a member of a collection of elements (the alphabet)
which serves to organise, control and/or present data. A glyph is a
recognisable, abstract, graphic symbol. The typefaces Times New Roman,
Zapfino and Helvetica light all have a euro character, however, you will
see, that each typeface has a different glyph to represent the character.
Which means that all three typefaces mentioned above, have three different
glyphs to represent that one character, the euro. (Courtesy: Linotype.com)
Unicode Fonts
A Unicode font is one which is based upon and supports the Unicode
standard. The basic idea behind Unicode is the unification of all written
systems of the world in one character set. Unicode uses a 16 bit character
sets, that is, 216 or 65,536 bits. That means that each character is
assigned a unique 16 bit code. The euro currency symbol, for instance,
has the code 20ac. To go back to the paragraph above, each of the three
glyphs have the same code because they represent the same character.
The large number of places is needed to be able to include some of the
larger alphabets, like Chinese, Japanese or Korean.
The Unicode standard covers not only letters and numerals but also
diacritical symbols, punctuation, mathematical and technical symbols,
dingbats, etc. In the latest version of Unicode, 3.0, 49,000 codes are
already assigned and 6,400 are reserved for private use. For example, if
a choreographer has symbols which she uses for her work, but which,
because of their very specific use, have no code, she can assign these
reserved codes to the symbols. Although the almost 65,000 codes of
Unicode should be enough for the world’s written systems, the expansion
system UTF-16 offers even more, 917,476 more codes, with 131,068
reserved for private use.
As it becomes more and more important to communicate with people all
over the world, the benefits of Unicode become more and more evident.
It is a universal system which will cover all symbols of the world’s written
language systems and then some. This means that the platform, the
operating system, the software you use will not affect the content of
your document even if you send it to someone who works with another
platform, operating system and/ or software. In other words, language,
whether of the software, the system, or the document, is no longer an
issue. Unicode is supported by important software manufacturers like
Apple, Hewlett-Packard, Microsoft, IBM, Oracle, SAP, Sun, just to name
a few. It is also a requirement for modern standards like XML, Java,
JavaScript, etc. All modern browsers support Unicode as well as many
operating system, among others Windows 95 and up, Windows NT 4.0
and up, Mac OS 8.6 and up, Linux and other Unix systems.
Unicode also offers an efficient way to deal with text. Because Unicode
is based on characters and not on glyphs, the way a text looks is not
important, only its content is. Unicode will tell any system which is
interested that the word with which it is working is composed of the
characters t, y, p and e, in that order. Whether the text is set in Times
New Roman or Helvetica is irrelevant, Unicode deals only with pure text.
This increases the efficiency of computers working with the text, as the
information they send, receive and analyse has only one unambiguous
meaning. (Courtesy: Linotype.com)
What is the Difference between PostScript and TrueType?
PostScript Type 1
PostScript Type 1 fonts can also be called outline fonts. They are a special
form of the PostScript programming language, themselves building
programs of their own, namely the font software. A font in the PostScript
language contains an organized collection of procedures to describe
the glyph forms. Different font programs contain different amounts of
information, gathered together in the so-called ‘dictionary’. The dictionary
saves the obligatory and optional entries and serves the PostScript
interpreter as a data object in order to access all font functions.
PostScript font technology makes it possible to scale fonts, meaning
to create the forms of the font in all point sizes. The major advantage
in comparison to metal type or bitmap fonts is that the user needs only
one font weight to create the forms of all point sizes. In relation to digital
typefaces, the disadvantage of outline fonts compared to bitmap fonts is
that the rasterizing takes time to compute and that outline fonts in small
point sizes do not reach the quality of hand-drawn bitmaps.
All glyphs of Type 1 fonts are described from abstract, mathematical
outlines of lines and curves. Points on these outlines describe the curves
and are differentiated as on-curve and off-curve points. On-curve points lie
on the outline of a glyph and off-curve points are part of on-curve points.
They control the form of the curves which describe a glyph.
TrueType
The TrueType technology is made up of two components: fonts in TrueType
font format and the TrueType rasterizer. Both are necessary to display and
print TrueType fonts on computer systems. TrueType is compatible with
both Apple and Windows systems, however, the TrueType font file created
for each operating system is different. Macs can use a Windows TrueType
font file but Windows can not use an Apple TrueType font.
TrueType is an outline font format which allows the scaling of typefaces.
This means that all point sizes of a glyph are made from one and the same
outline. The file itself contains different data blocks or tables which are
accessed with a table directory. These tables contain information about the
glyphs, outlines, bitmaps and other typographic and font specific data.
TrueType has three glyph types: simple, combined and glyphs without
contour. Simple glyphs contain compressed outline and hinting data.
Combined glyphs, often used for accented glyphs, base their outlines
on other glyphs, whose components are again based on other simple
or combined glyphs. A combined glyph contains the hinting for each
component individually. Glyphs without contour, for example, the space,
define the behaviour of a text, have however no glyph of their own and
hinting cannot be applied to them.
Outlines describe glyph forms mathematically and are constructed of
on-curve points and off-curve points. Two on-curve points in a row will be
connected by a line; curves are defined by quadratic B-splines. Each spline
consists of a number of quadratic Bézier curves which are defined by three
off-curve points.
The user generally never sees the outlines of a font. This is because
both screens and printers use a bitmap matrix for display. The outlines
of a TrueType font are scaled to the desired size or turned to the desired
position and then converted into bitmaps. Turning a pixel on or off depends
directly on the outline and follows these rules:
1. If the middle of a pixel is within the outline of a glyph,
the pixel will be turned on and become part of the glyph.
2. If the outline falls exactly on the middle of a pixel,
the pixel will be turned on.
A Question of Format
So which of the two font formats is better? The answer is anything but
simple and must be seen from a variety of angles. Both formats, TrueType
and Type1, consist of algorithms or instructions with which an outline
font can be rasterized in pixels for display. The main differences between
the two formats are of technical and philosophical nature, as well as
dependent upon various corporate policies.
Technical
Regarded technically, the hinting process of the TrueType technology is
superior to that of Type 1 because it allows instructions in three directions,
down, up and diagonal. Type 1 only allows upward and downward hinting.
In connection with Apple and Microsoft it must also be noted that Type 1
fonts need the ATM while TrueType is an integrated part of both systems.
Philosophical
When TrueType and Type 1 fonts are used in the same situation, meaning
same operating system and same end machine, the differences are
minimal, usually even imperceptible to most users. The use of a particular
format is today simply a matter of user preference.
Corporate
PostScript Type 1 is a development of Adobe Systems and was accepted
for some time as the standard for scalable fonts. Adobe kept the format
a secret and therefore kept a monopoly on this format. Apple Computer
Corporation retaliated by developing its own outline font format, TrueType,
which was later purchased and further developed by Microsoft.
(an excerpt from: Ivir, Milo. ’Entwicklung digitaler Schrifttechnologien
und ihre Einflußnahme auf die Typografie im Zeitalter des elektronischen
Publizierens’ (The Development of Digital Font Technologies and their
influence on Typography in the Age of Electronic Publishing). Diploma
thesis, Institute for Technology and Print Planning, College of Art, Berlin,
1998)
