Graphics Reference
In-Depth Information
DIGITAL TYPESETTING
1970s to present
A computer in combination with the high-resolution cathode ray tube
(CRT) and laser revolutionized the communications industry. Using
only electronic rather than mechanical components, computers set
and process type at speeds never thought possible. In addition, the text
type from digital typesetters rivals the quality of photo type.
Digital typesetting systems encode typographic characters
digitally on a grid, defining the shape of each letter as a certain
number of distinct points. Every detail of a letter is defined, including
horizontal strokes, vertical strokes, and curves. The coded characters
are stored electronically as digital instructions designating the x
and y coordinates of the character on the grid. In the earliest digital
typesetters, these instructions were sent to a CRT, where the character
is generated onto the computer screen.
The degree of resolution in digital letterforms is an important
consideration. Basically, the more dots or lines used to describe a
letterform, the higher the resolution. Because letters are constructed
on a grid, the curved lines consist of a series of stair-stepped contours
(Fig.
7-17
). When more dots are used to represent a curve, the curve
appears smoother to the eye. The quality of letterforms is determined
not only by their design but also by their digital resolution (Fig.
7-18
).
Resolution is improved through a process called hinting (see
Chapter 8), which mathematically encodes letterforms in a manner true
to their original design. Each size of a well-designed typeface possesses
characters with unique proportional characteristics, and hinting
preserves these characteristics, a concern particularly relevant for
typefaces of smaller size. Details of curves, strokes, and serifs maintain
optical integrity.
7-19
Components
of a digital-scanning
typesetter.
7-17
Curved lines
consist of a series of
stair-stepped contours in
digital letterforms.
7-18
Examples of
digital letterforms,
demonstrating decreasing
resolution, from left to
right, as the number of
dots is reduced.
