| Image
quality, the most important feature of a monitor,
is also the hardest to judge. Good is a subjective
term, so relying on the judgment of reviewers (such
as CNET) may not get you exactly what you want. Further,
like a snowflake, every monitor is unique. There can
be significant differences from one monitor to another--even
among the same make and model. It's unrealistic to
expect to run a comprehensive diagnostic on a monitor
before you buy it, but here are some of the most important
qualities to look for when choosing a CRT or an LCD.
LCDs:
what to look for
- Choose a
monitor that automatically adjusts to the
timing of an analog (VGA) signal. You want
to see stable gray and patterned images
with no pixel jitter.
- Find a monitor
with good viewing angles. Colors and brightness
should not change in the corners of the
screen, where the viewing angle is the greatest.
- Pick a monitor
that looks uniformly bright when viewing
both dark and light images.
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Tips
and tricks: assessing LCD image quality
- Check for
dead pixels, ones that are always off. It's
not uncommon for monitors to have one or
two defective pixels--especially larger
models--but you want as few as possible.
Open Internet Explorer, in the address line
type about:blank, and press Enter.
Then press the F11 key to make it full-screen.
Look for small black specks that are not
dust or debris on the screen. (Press F11
again to see the Explorer toolbars.)
- Check for
stuck pixels, which are always on. Right-click
the Windows Desktop, pick Properties, then
choose the Screen Saver tab. Choose Blank
from the list of screensavers, then hit
the Preview button. Look for any glowing
red, green, or blue spots. (Press any key
to return to the Display Properties window.)
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CRTs:
what to look for
- Find a monitor
with good convergence (clean white lines
with no colors on the edges), as this increases
image sharpness.
- Choose a
monitor with good screen geometry, especially
if you intend to use it for design or drawing
tasks.
- Pick a monitor
with good image regulation; you want an
image that does not change its dimensions
or distort when the content of the image
changes. Poor image regulation can be a
problem with lower-priced models and displays
that are operated at the upper limits of
their specifications.
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Tips
and tricks: assessing CRT image quality
- Check the
convergence of the display. Open Windows
Paint and start a new image. Choose Image,
then Attributes, and change the size of
the image to the same number of pixels as
the current resolution (to check the resolution,
right-click anywhere on the desktop, select
Properties, then choose the Settings tab).
Use the Fill tool to fill the screen with
black. Then choose the Rectangle tool, set
the drawing color to white, and draw a box
that fills the screen, starting in the upper-left
corner. Scroll to the bottom-right corner
of the image and draw another box that fills
the screen. Now choose View, then View Bitmap
to see the image on the full screen. You
should see a black screen with two intersecting
white rectangles. Check the white lines
closely; you should not see any areas where
the lines separate into colored lines. A
slight color tinge along the edges of a
line is acceptable, but a pure white line
is best.
- Check the
screen geometry. Look to see that the lines
drawn in the previous step are straight.
You can also draw a circle in the center
of the image using the Circle tool (hold
Shift down to draw a perfect circle), then
copy and paste the circle in the corners
and along the edges. Look to see that they
are round--not squashed or egg-shaped.
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Good
geometry |
Bad
geometry |
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