Specifications

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Chapter 15 Video Hardware
Figure 15.9 Typical geometry errors in CRT monitors; these can be corrected on most models that have
digital picture controls.
Although LCD panels aren’t affected by geometry errors as CRT monitors can be, they can have their
own set of image-quality problems, especially if they use the typical 15-pin analog VGA video connec-
tor. Pixel jitter and pixel swim (in which adjacent pixels turn on and off) are relatively common prob-
lems that occur when using an LCD monitor connected to your PC with an analog VGA connector.
Testing a Display
Unlike most of the other peripherals you can connect to your computer, you can’t really tell whether
a monitor suits you by examining its technical specifications. Price might not be a reliable indicator
either. Testing monitors is a highly subjective process, and it is best to “kick the tires” of a few at a
dealer showroom or in the privacy of your home or office (if the dealer has a liberal return policy).
Testing should also not be simply a matter of looking at whatever happens to be displayed on the moni-
tor at the time. Many computer stores display movies, scenic photos, or other flashy graphics that are all
but useless for a serious evaluation and comparison. If possible, you should look at the same images on
each monitor you try and compare the manner in which they perform a specific series of tasks.
Before running the tests listed here, set your display to the highest resolution and refresh rate allowed
by your combination of display and graphics card.
One good series of tasks is as follows:
■ Draw a perfect circle with a graphics program. If the displayed result is an oval, not a circle, this
monitor will not serve you well with graphics or design software.
■ Using a word processor, type some words in 8- or 10-point type (1 point equals 1/72''). If the words are
fuzzy or the black characters are fringed with color, select another monitor.
■ Display a screen with as much white space as possible and look for areas of color variance. This can
indicate a problem with only that individual unit or its location, but if you see it on more than
one monitor of the same make, it might indicate a manufacturing problem; it could also indi-
cate problems with the signal coming from the graphics card. Move the monitor to another sys-
tem equipped with a different graphics card model and retry this test to see for certain whether
it’s the monitor or the video card.
Barrel
distortion
Pincushion
distortion
Parallelogram
distortion
Trapezoidal
distortion
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