If you’re reading this
article on your computer, there’s a good
chance you won’t get all the way to the end. Not because
you won’t find it utterly fascinating (trust me!), but
because it will be hard on your eyes.
It’s not sentimentality that makes most people prefer
reading books and magazines to squinting at their
laptops. The quality of computer text is awful. It
doesn’t have to be.
The chief problem is the low resolution of computer
screens. The color LCD screens on most laptops and
desktops today have a resolution of only about 100
pixels per inch. You need at least two or three times
that many pixels to begin to approach the quality of the
printed page. The output of even a cheap laser printer
is six times as good.
What’s more, screen resolutions have hardly budged in
the last several years, for a variety of reasons. For
one, you’d need a lot more computational power to make a
difference you could easily see on your screen. Moving
from 100 ppi to 200 ppi, for instance, means your
computer would have four times as many pixels to fill,
and that in turn would probably bog down your graphics
processor or, in a laptop, quickly drain your battery.
Moore’s Law will eventually give us faster chips, and
new integrated-circuit designs are getting more
power-efficient. But making computer displays with
higher pixel densities is also costly, because you’re
more likely to get dead pixels during manufacturing.
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The resolution gap didn’t matter much in the days when
most people never had to read long or detailed material
on their computers. But that option is becoming less and
less realistic, as publishers, companies, and other
organizations increasingly turn to the Web to put out
their articles, manuals, and other original content. Of
course, many people can and do print the material before
reading it. But that’s not a very efficient option, and
it’s at odds with longer-term trends in publishing (to
say nothing of longer-term trends in forestry).
Analysts envision that in coming years, readers will
download more and more text to compact, handheld
devices, enjoying instant, inexpensive, mobile, and
customized access to news, books, e‑mail, reviews,
directions, and all the other tidings of everyday life.
In other words, we’ll all be spending more and more time
reading onscreen.
As it is, the average office worker already spends the
better part of the workday at the computer. It makes
good economic sense, then, to improve the reading
experience. Jakob Nielsen, the Web usability guru, has
calculated that boosting a worker’s onscreen reading
speed by just 10 percent would save his or her employer
about US $2000 each year, through added productivity.
So, given that the need for a better onscreen reading
experience is there, but not the pixel density, what’s
to be done? Plenty. Research groups like the Advanced
Reading Technologies team at Microsoft, of which I’m a
member, are working hard on the problem. Type designers,
cognitive psychologists, and computer scientists and
engineers are collaborating to figure out ways to
present text that is both aesthetically pleasing and
easy to read and comprehend. The secret to better
computer text, it turns out, is a heady mixture of art,
science, and technology.
You may not even
realize how much time you spend reading from
your computer screen. You might be surfing the Web,
scanning e-mail, composing a report, filling in a
spreadsheet, or writing software, but what you’re really
doing is reading. In fact, reading is probably the task
we perform most frequently on computers. Spend too much
time staring at your monitor, though, and the inevitable
happens: your eyes hurt, your head aches, and your
thoughts may even fog up. Eventually, you reach a point
where you can’t read any further.
What is the longest document that you’re willing to
read on screen? Five years ago, many people would print
out anything longer than a page. These days, they may
read on for several pages without feeling the need to
print. The way text is presented onscreen has gotten
better—not perfect, or even very good, but better.
One of the main improvements is in type design. Over
centuries, type designers came up with an assortment of
visual tricks to appeal to the human eye and get people
to keep reading. One key quality they strive for is
symmetry. Readers will perceive letters and words that
aren’t symmetrical as ugly—even if they don’t notice
this asymmetry consciously, it will still degrade their
reading experience on some level. To achieve a
symmetrical look, font designers try to keep the stem
widths of letters and the spacing between letters as
even as possible.
Designers also have tricks for specific letters. In
grade school, for example, you were probably taught that
capitals are supposed to reach from the baseline to the
capital line and no further. But type designers usually
ignore this rule. Rounded letters—such as O, C, and
Q—often reach above the capital line and below the
baseline [see figure, “Tricks
of Type”]. Without that extra padding,
those letters would look smaller than the rest.
Or take the letter X. What could be simpler than those
two intersecting diagonals? But a typed X with perfectly
straight lines looks strange—specifically, the top
right arm will appear misaligned with the lower left leg
[see figure, “The Secret of
X”]. To compensate, type designers shift the
top right arm slightly downward to give the appearance
that it’s in line with the left leg.
Back when typesetting was still done by hand, letter
by letter, and space by space, designers rendered such
tricks in metal dies. When personal computers came
along, the cramped, low-resolution monochrome CRT
monitors didn’t allow for much nuance in type design,
and reading from those early screens was pretty
grueling.
In the 1980s, with the advent of graphical user
interfaces and desktop publishing, things started to
improve. Of course, taking typographic rules that had
been developed over centuries for the printed page and
rendering them in pixels on the screen wasn’t, and still
isn’t, straightforward. At first, font producers
represented each letter with a unique
bitmap—essentially, a bunch of rows and columns of
pixels that were either on or off. A digital font
consisted of thousands of these bitmaps for every
letter, number, and symbol and for every point size,
style, and resolution. The Japanese font set MS Mincho,
for example, contains about 128 000 embedded bitmaps.
Today’s computer fonts are more streamlined. Rather
than individual bitmaps, they rely on scalable outlines
of each letter. To display a letter onscreen, the font
software running on your microprocessor takes the letter
outline, automatically scales it up or down to the
desired size, and then creates a bitmap of the letter on
the fly. It takes at most 20 milliseconds from the time
you strike the key to the time the letter is displayed.
It’s faster and saves on disk space to create an outline
for each letter, rather than calling up a discrete
bitmap from memory every time you need to display that
letter [see figure, “Getting Pixelated”].
The downside to using scalable outlines is that the
resulting bitmap can contain rounding errors; one
vertical stroke, or stem, on an “m” might come out to be
two pixels wide, while the other stems are one pixel. To
correct these rounding errors, the font software
includes instructions, known as hints, that subtly
adjust the letter’s outline so that the resulting bitmap
is even and legible. Some hints are applied across a
font so that, for instance, all of the lowercase letters
have the same height and all of the stems of the letters
have the same thickness. Other hints are specific to a
letter, or even to a letter at a specific size [see
figure, “Hint,
Hint,” for examples of a letter before and
after hinting].
In the early days of computer fonts, each hint had to
be programmed by hand; there might be an instruction to
tell a single pixel to turn on or off for a specific
letter at a given resolution. Some fonts in Microsoft
Windows 3.1, for instance, took up about 25 000 lines of
code, much of it related to hinting. With time, font
hinting has become more streamlined. These days,
font-hinting algorithms can dramatically cut the amount
of time needed to develop a new font. Programming the
initial hinting for the Windows 3.1 fonts took about 18
months and involved 18 type designers and about
6 engineers. Today one designer can hint a high-quality
typeface in two months or less.