Graphics Reference
In-Depth Information
BASIC PRINCIPLES OF LEGIBILITY
As signs representing sounds in spoken language, letters are basic to
legible typography. The primary purpose of a letterform is to convey
a recognizable meaning to the mind. Therefore, letterforms must be
designed with clarity, each being distinct within the alphabet. The
contrast among individual characters makes it possible for the reader
to decipher written information without confusion.
The most legible typefaces are those timeless examples
characterized by three qualities upon which legibility is dependent:
contrast, simplicity, and proportion. These typefaces exemplify
beautiful and functional letterforms. A close look at typefaces such
as Garamond, Baskerville, and Bodoni will reveal why their forms
are as vital now as when they were first designed. (See the type
specimens in Chapter 13.) The use of well-designed typefaces,
however, is no guarantee that typography will be legible. Effective
typography depends upon such factors as the communications
context and the subtle adjustment of letterforms and their spatial
relationships, each of which may have an effect upon how easily
typography is read. Making type legible is a masterful achievement,
requiring a process of intelligent decision making.
In the strictest sense, legible typography is a means of
communicating information objectively. However, typographic designers
sometimes bend the traditional criterion of legibility for expressive
purposes. Designers, with their instinctive curiosity, have experimented
with typography, playing with forms, imposing new meaning, and
changing the standards of typographic communication. Innovative
typography poses original questions, challenges edicts of the past, and
redefines the concepts of legibility and functionality.
This chapter approaches legibility as an art of spatial synthesis.
As an art, it is not absolute. Therefore, information derived from
legibility research should be considered only a guideline. The
knowledge designers have of legibility is based upon a legacy of
typographic history and a keen awareness of the visible world.
This knowledge will continually evolve, creating new standards for
readability and functional typography.
Distinguishing characteristics of letters
The alphabet consists of twenty-six letters, each of which has evolved
over the centuries to a unique place within this system of signs. This
evolution has occurred gradually. It is no accident that the individual
shapes of letterforms have developed out of a need to improve the
communication process. As the alphabet has evolved, it has become
a flexible system of signs in which all letters are distinct, yet all work
together harmoniously as visible language.
In spite of the innumerable variations of size, proportion, weight,
and elaboration in letterform design, the basic structure of each
letterform must remain the same. For example, the capital
A
always
consists of two oblique strokes joined at the top and connected by a
horizontal stroke at their midsection. Sufficient contrast must exist
between the letters in a font so that they can be easily distinguished
(Fig.
3-1
).
3-1
As the top stroke
of the letter
a
rises to
become the ascender of
the
d
, intermediate forms
are not easily deciphered
by the reader.
Letters can be clustered into four groups, according to their
contrasting properties. These are letterforms with strokes that are
vertical, curved, a combination of vertical and curved, or oblique
(Fig.
3-2
). From these groupings, one notices not only that letters
are similar in many ways but also that there are some important
differences. Obviously, letters with similar characteristics are more
likely to be confused, while letters with distinct qualities provide
contrast within a word. Letters within a word are most legible when
they are taken, in equal number, from each group.
il
acegos
bdfhjmnpqrtu
kvwxyz
EFHILT
COQS
BDGJPRU
AKMNVWXYZ
3-2
Four groupings
show the structural
relationships of all
letters in the alphabet.
The divisions are based
on the dominant strokes
of each letter.
