Tricks of the trade
That’s the theory, at least. Overdriven
panels are definitely sharper when displaying movement, but close inspection of
some overdriven monitors reveals something slightly rotten. The first problem
is usually referred to as inverse ghosting. This often manifests as a trail of
shadows in the wake of a moving object, approximately in the opposite colour to
that object. It’s quite distinct, therefore, from the smeared trail seen on
monitors with poor pixel response. This is due to excessive overdrive leading to
pixels overshooting the required colour state.
Inverse ghosting can affect both TN and PVA
panels with overdrive technology, but the other major problem — input lag,
seems to be restricted to PVA screens. The problem here is a measurable delay
between the video signal being sent to the monitor and the screen responding
with a refreshed image. Typically, this is noticed as a lag between a physical
mouse input and the movement of the cursor, crosshair or application window on
the screen.
Of course, the method of processing a
digital signal results in at least some lag on all LCD screens compared to the
instantaneous output of an analogue CRT monitor. Using a CRT monitor in cloned
mode as a control device, LCD screens usually lag behind by 10 to 20 milliseconds.
With some overdriven screens, this increases to SO milliseconds or more. The
result is a sticky, disconnected feel on the desktop. That’s a serious problem
for gaming, and can make first- person shooters in particular almost
unplayable.
That’s the major panel technologies all
summed up, but there are one or two universal issues to address. The first is
video interfaces. In theory, alt the major digital interfaces are quite
similar. You can’t see the difference between DVI, HDMI and DisplayPort. In practice,
however, HDMI can present problems. With certain video card and driver combos,
HDMI connections ran throw up scanning issues that prevent the panel running
pixel for pixel.
In other words, you can’t achieve native
resolution, and that’s critical for any LCD. Admittedly, most PCs won’t suffer
from this problem, but when it does happen, it can be insurmountable short of
buying a new video card. Our advice is not to go with any monitor that is
restricted to HDMI.
Next up are the related issues of resolutions
and aspect ratios. For the most part, the monitor industry has settled on full
HD 1O8Op or 1.920 x 1,080 for the former and therefore 16:9 for the latter. The
first implication of this is that it usually doesn’t matter what size screen
you go for, your resolution and desktop space or in-game detail will be the
same. Indeed, you could argue larger screens look worse. You just end up with
bigger, jaggier looking pixels.
However, if you mainly use your PC for
gaming, a bigger screen gives you the option of sitting further away. Larger
panels are also handy for watching TV and movies, but there are a few
exceptions to this rule of ubiquitous i080p. A few monitors are still available
in 16:10 aspect. Most common among these are 24-inch panels with 1,920 x 1.200
pixel grids. That’s a useful dollop of vertical pixels. And let’s be clear,
vertical pixels are really useful for normal PC usage rather than watching HD
movies.
The best eyeful
A few monitors are available with the
slightly higher
A few monitors are available with the
slightly higher 2.048 x 1,152 resolution. The problem is. it’s only a small
increase over 1080p, and it’s still 16:9. Finally, at the top end you have the
two ultra-high resolution panels in the shape of 27-inch running 2,560x 1,440 pixels
and 30-inch 2,560 x 1,600.
We’ve extensive experience running both of
those options and we heavily favour the latter. It’s a subjective issue, but
the 30-incher feels larger, more expansive and more luxurious well beyond the
extra three inches and 160 vertical pixels. Anyway, the great shame about these
panels is that prices haven’t really shifted since the first 30-inchers
appeared five or six years ago. You’re still looking at the best part of a
grand for a 30-incher. The 27-inch alternative can be had from around E500, but
that’s an awful lot to spend on something ever so slightly suboptimal.
The joy of specs
Those little white lies the screen
makers tell you...
Muscle your way through the main body of
this in-depth screen guide and, if nothing else, you’ll learn there’s a big
difference between the three major LCD panel technologies. Oddly though,
that’s far from obvious if you peruse the quoted specifications.
As we’ve explained elsewhere, you can
sometimes pick up a few pointers from the viewing angles, but even then, the
yawning real-world gap in viewing angles really doesn’t come across in the
difference between, say, 160 degrees and 178 degrees.
Elsewhere, things can be even more
misleading. Take colour depth. The simple fact Is that TN panels are only
capable of natively rendering 6-bit colour. That means 64 shades per primary
colour channel and in turn a total of 262,144 colours. Odd, then, that most,
If not all, TN monitors claim to offer 16 million colour5 and therefore 8
bit5 per channel.
The explanation is dithering, which
allows additional colours to be simulated courtesy of rapidly alternating
between two adjacent hues. Your eye does the rest, generating a mental
average and therefore a colour the panel can’t actually display. It’s a
clever trick, but it’s never going to be as good as a native palette of 16
million colours, much less the billion hues available from the latest panels
offering 10 bits per channel.
Contrast is another tricky specification.
Many screens offer dynamic backlight control, which in a very strict sense
allows huge contrast ratios. In practice, however, the best results come from
panels capable of higher contrast without the need for a dynamic backlight.
The thing is, if you’re a monitor manufacturer, do you quote the 800:1 ratio
your screen does with the backlight in static mode? Or do you go with the
100,000:1 that it manages in dynamic mode? Well, quite.
Top Tips
Don’t Rely On HDMI
Some video cards using HDMI may result in
fuzzy, incorrectly scanned image quality that can sometimes be impossible to
correct. Make sure your / screen supports DVI or DisplayPort.
