Large screen monitors for better viewing
| Date | 01 February 1993 |
| Pages | 127-130 |
| Published date | 01 February 1993 |
| DOI | https://doi.org/10.1108/eb045222 |
| Author | Howard Falk |
| Subject Matter | Information & knowledge management,Library & information science |
Hardware Corner
Large screen monitors for
better viewing
Howard Falk
Although the computer world currently seems to favor color
displays with screen images only about nine inches wide,
such displays are not suitable for many library applications.
Computer
users
who need to view periodicals, photographs or
video materials require more detail on the screen than ordi-
nary small color monitors can provide.
Large screen monitors are considerably more expensive
than their smaller counterparts, but
as
more and more material
becomes available on CDROM, from online databases and in
other computer-readable formats, demand for larger monitors
is bound to increase.
Although large-screen color monitors are available, black
and white units offer interesting features. These include lower
cost, higher resolution and superior overall image quality. In
situations where text, black and white graphics or videos are
the main concern, color may play little or no role. In addition
to the traditional black and white monitors, which display
simple black and white characters or areas on the screen,
grayscale monitors are now available. While black and white
is adequate for displaying text, these grayscale monitors can
represent photographic images in multiple shades, providing
fine presentation of pictures that could not be portrayed satis-
factorily by simple black and white monitors.
How screen size is measured
Monitor sizes are given in inches and this measure is diago-
nal.
For example, the face of
the
glass CRT tube in a 17-inch
monitor should measure 17 inches from the upper left hand
corner of the face to the lower right hand corner. However, in
any monitor the tube face is partially covered by the monitor
casing, so the exposed tube face will typically measure only
about
16
inches diagonally.
In addition, the rectangular on-screen image displayed on
the monitor when it is in use is necessarily smaller than the
exposed tube face, since the edges of the image are straight
while the edges of the exposed tube face are curved. For ex-
ample, a typical 17-inch display will show an on-screen im-
age that measures less than
11
inches by less than 9 inches.
For purposes of this
article,
monitors with 17-inch or larger
tubes are considered to be large screen units.
Assuring a clear displayed image
The whole point of a large monitor is to give the user a clear
view of text, graphics or both. Characteristics of monitors that
affect display clarity include resolution and dot pitch.
Resolution of the display is given in pixels (tiny picture
elements). A resolution of 1280 x 1024 (1280 horizontal
pixels by 1024 vertical pixels across the display) is desir-
able for applications where the user may be viewing two or
more windows at once, or must accurately observe detailed
material such as small type and punctuation. Resolutions as
high as 2048 x 1536 are available for some large screen
monitors.
Resolution determines the amount of information that can
be presented on the screen. For example, a 1280 x 1024 dis-
play makes
66%
more information available than does a 1024
x 768 display.
The size of
the
on-screen image may vary, so resolution is
not the best measure of
the
sharpness of the displayed image.
The fineness with which details can be viewed
is
more exactly
defined by the dot pitch, which gives the distance between
pixels in the display. Dot pitch for large screen monitors gen-
erally ranges from 0.28 millimeters to 0.41 millimeters, with
pitches of 0.31 millimeters or less considered most desirable.
Another way to express the closeness of dots is to cite the
number of dots per inch for
a
display.
The equivalent of
a
0.31
millimeter dot pitch would be about 79 dots per inch.
The best way to determine overall image quality
is
actually
to look at
a
number of different displayed images on the moni-
tor being considered. Monitors with the same specifications
can give very different results. For example, one 19-inch
monitor that provides 16 levels of gray at 1280 x 960 pixels
and has a 64Hz refresh rate may show sharp, clear images,
while another with the same specifications may provide im-
ages that are muddy and hard to see.
A
careful observer will take note of
the
sharpness of focus
over the entire screen, will look carefully for distortion
around the edges and will evaluate text readability. One sim-
ple test is to view some lines of 6 point type (displayed in
correct size) and compare their readability with similar
printed text. Incidentally, the average
12-
to 14-inch monitor
driven by a VGA board will fail this test.
In black and white, or gray, or color displays, the blacks
should be dark and the
whites
bright.
If you compare a number
of monitors from different manufacturers, you will soon be-
come aware that some blacks have a greenish or bluish
cast,
or
The Electronic Library, Vol.
11,
No. 2, April 1993 127
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