| Video Noise August 2002
Basic TV Adjustment --
Part One
This month is basic training time. Video-monitor-adjustment
basics, that is. What are those controls on your TV and what do they do? Read on.
You need a test disc
There is a mini-industry centered around test and setup
DVDs to help you get your TV’s controls set optimally. And to be perfectly honest,
you can’t really get them set correctly without one of these discs. You can get
moderately close without one, but you’ll learn a lot from the test disc. The common
titles are Video Essentials, Ovation Software’s AVIA Guide to Home Theater,
and the disc put out by Sound & Vision magazine, Home Theater Tune-Up.
The first two DVDs cost more but contain more advanced help. Video Essentials
assumes the most knowledge on the part of the user. The AVIA DVD is better suited
to the serious home-theater enthusiast who is also interested in some advanced test and
setup capabilities for surround sound.
These DVDs will take you much closer to the ideal setup of
your monitor than I can do in words alone. I can help you understand what each control
does, though, and give an idea of how each control should be set for the best picture.
The controls
CRT (cathode ray tube) display devices like direct-view and
rear-projection TVs will have similar, basic controls. Understanding these controls and
what they do is the first step to getting your TV picture looking as good as it possibly
can. The controls for LCD, DLP, and D-ILA projection systems, as well as plasma displays,
can be quite different, so refer to the manufacturer’s documentation for those
systems for proper use of their controls. You should plan to watch TV in a darkened room
to get the best picture quality. To compliment viewing in a darkened room, you will want
to set the TV’s controls under those conditions. OK, let’s look at each control,
one at a time.
Color: The color control is like a volume control
for color intensity. Turn it up and the colors get louder. Turn it down and the colors
become softer and more muted. I would estimate that 90% of the TVs in use today have the
color control turned up too far, making colors unnaturally intense. This causes a
considerable loss of detail in the picture, as well as taking all the subtle shading of
colors right out of the picture.
The proper setting for the color control is the point just
before flesh tones start to appear exaggerated. Most people must think flesh tones on
TV are about 10 times more intense than real-life flesh tones -- or they wouldn’t be
running their color control so high! Crank the color control down until the picture seems
a bit dull and that should be just about perfect.
Tint: The tint control is like the balance control
for your stereo system. Turn the balance one way and the sound moves to one side; turn it
the other direction and the balance moves to the other side. The tint control adjusts the
balance between green and magenta. Magenta is a color that is half red and half blue. By
having the tint control adjust the balance between green and magenta, the TV set allows
you to balance the amount of green to the amount of red and blue.
Human vision is more sensitive to green than any other
color. That’s why green is by itself, and red and blue are combined. Setting the tint
control is something most people probably do fairly well. Flesh tones of all skin shades
are your best reference. You should try to get a natural appearance that is neither too
green, nor too magenta. Since most of us see flesh tones all day long, we have a pretty
good memory for what looks reasonably realistic on our TV sets.
Contrast: The contrast control is not what most
people think it is. It doesn’t do anything at all for "contrast," which is
the difference between shadows and highlights. A real contrast control would leave the
blacks and whites alone, but it would either stretch out or compress the number of shades
of colors (and grays) between completely black and completely white. TV’s founding
fathers deemed the concept of "white point" too complex for the average American
TV viewer to comprehend. So, they gave it a different name that completely obscured the
true nature of what this control does. Your contrast control actually sets the "white
point." That means it controls how bright the whites are. But you thought white was
white, right? Well, that’s not true.
If you line up three identical lamps and put a 30W bulb in
one, a 60W bulb in the middle one, and a 100W bulb in the other one, and then light all
three of them at the same time, you’ll see the difference. The 100W bulb is the
whitest and brightest, the 60W bulb is next, and the 30W bulb is looking pretty weak by
comparison. Think of the contrast control as the "treble" control of your TV --
it controls the "high end" of the TV picture: the whites.
The trick with your TV is to set the contrast control so
that whites are white and bright, but not so white that the picture tube is worn down
faster than it should be. And not so white that detail is lost, either. Unfortunately,
most TVs come from the factory with the contrast control set to maximum. This makes the
set look bright in stores when there are 50 TVs on a big wall. If the manufacturer set
contrast to the correct level, their set would look bad compared to all the other brands,
especially to the average consumer who is unaware of the trick and its tradeoffs.
Because high contrast settings wear down your picture tube
rapidly, rear-projection TVs should have their contrast controls set to a lower level
immediately after powering up for the first time. Never, ever buy a demo TV off the
showroom floor. That set has likely been running 10 to 12 hours a day, every day, with the
contrast control set to maximum. The picture tube(s) has been driven so hard for so long
it is probably equivalent to six years of normal use with the contrast control set to a
reasonable level. Why spend good money on a new TV that already has years of use on its
clock?
Most TVs will give you the best picture with the contrast
control set between 50% and 75% of its highest setting. You want to use the lowest setting
that still makes the picture look good. When turned up too high, whites will bleed out of
their borders, or "bloom" around the edges of bright objects, which will reduce
the apparent sharpness of the image.
This control can be very difficult to
set to the correct level even if you have one of the test/setup DVDs. You will probably
find that there is not one specific, right setting, but you will find the correct
operating range where you get nice bright whites without blooming.
Next month we’ll look at brightness, picture,
sharpness, and color temperature. Stay tuned.
...Doug Blackburn
db@hometheatersound.com |
