| Video Noise September 2002
Basic TV Adjustment --
Part Two
In last month’s article,
we covered some basic controls: color, tint, and contrast. This month, we’ll look at
some more of the controls and knobs you might find on your TV, and how to use them.
Brightness: The brightness control is something like
the bass control for your stereo system. I suspect that back at the dawn of the television
age, the TV committee decided that the actual function of the control was beyond the
comprehension of the consumer. The brightness control allows you to set the "black
point" of your TV screen. Set the brightness control too low and you will lose detail
in the shadows. Set the brightness control too high and you will never see true black in
your picture. The blacks will become dark gray instead. This is another control that
really benefits from the test patterns available on one of the test DVDs.
Setting the brightness level is best done when the room is
dark. Get an image on the screen that is black or mostly black. Move closer than usual to
the screen so you can see the lines making up the image. Turn the brightness control up
until dark-gray lines replace true blacks across the screen, then turn the brightness
control down until the black parts of the screen are as black as they can get. Sometimes
this will be the final setting. Other times, you may have to kick the brightness level up
one or two notches to show just the slightest bit of dark-gray character to the black
background.
Picture: If the contrast control adjusts the whites,
and brightness controls the blacks, what does a picture control do? Some manufacturers
omit the contrast control and replace it with picture control. In some cases, the picture
control is identical to a contrast control. In other cases, when you adjust the picture
control, you are adjusting contrast and brightness at the same time. This kind of thing
might be enough to prevent you from getting the best-possible image quality. If you sense
that the picture control on your set is adjusting both contrast and brightness, you may be
somewhat more compromised in your ability to get an ideal-looking picture. Or you might be
lucky and have no problem with it at all.
Sharpness: Next we have the evil sharpness control.
It was devised by truly evil minds. This control is supposed to make images look
sharper. What it does is exaggerate the transitions between differently colored objects or
between black and white edges. A proper transition would be for something to be black at
one instant and white at the next. In the real world of TV sets, you can’t make that
happen instantaneously. To make up for that, some propeller-head decided that by
artificially enhancing edges, you could make an image better looking. Boy, was he wrong.
The proper setting for the sharpness control in most TV sets is zero, as in completely
off. This removes the artificial edge enhancement and makes everything look better on the
screen.
If you happen to have a high-definition TV, you should know
that the sharpness controls on some new sets will look best set to 30% to 70% of their
maximum setting -- not zero. The sharpness control can work differently in HD sets and
should be well tested on a brand-by-brand, model-by-model basis to find the best setting.
When you get sharpness adjusted correctly, at first the image may seem a little soft. But
closer examination will reveal detail in the image that was obscured by having sharpness
set too high.
Color Temperature: Lastly, there is the
nearly-as-evil-as-sharpness control, the color-temperature control. Most TVs with a
color-temperature setting will have two or three adjustment choices. If there are three
settings they will often be called cool, neutral, and warm. These correspond roughly to
D9000-D9600 for cool, D6500 for neutral, and D5000 for warm. These numbers are a
representation of the color spectrum and what we think of as white light. In fact, white
light can go from nearly amber low-powered light bulbs to whites so bright they challenge
the sun. The bluer, or cooler the white is, the higher the color temperature. The more
yellow, or warmer the white is, the lower the color temperature.
To compete in the world of retail TV sales, manufacturers
think they have to have very hot whites. So the default setting for the color-temperature
control in sets that have them is cool, because anything warmer than that will look yellow
on the big wall of TVs at the electronics superstore. But the cool setting will make
whites look a bit blue-tinted and all the other colors will favor blue a little too much
to look natural. The broadcast standard in the U.S. is D6500. This color temperature is
considered the closest thing to neutral-white as possible.
The warm setting casts a romantic golden tone over the
entire image. But this is easy to recognize as too warm without too much trouble.
The problem people run into with color temperature is that changing from cool to neutral
makes neutral seem too warm/yellow for a few minutes as your vision becomes adjusted to
the more natural light balance.
As with everything, there are exceptions to how
color-temperature settings work in some brands and models. In rare cases, the
warmest-looking setting is close to D6500. This gives seriously warped manufacturers the
ability to put D9000-D9600 in the middle setting, then go crazy nuts with the top setting
being D12,000 or there about. This gives them an edge at the superstore where the mere
presence of this off-the-chart blue color temperature will make the rest of the
manufacturers’ sets seem to be too warm and too yellow. It’s just a trick, but
you may be the trickee if you aren’t careful to set the color-temperature control to
the setting closest to D6500.
There is no way for you to know for certain if you have
selected the right setting unless you have instrumentation. My best advice is to watch the
set for a few days in each setting. The warm setting will still seem too yellow even two
or three days later. When you have identified that setting, the proper color-temperature
setting will most likely be the next highest setting. You will find that this setting
produces the best-looking green foliage, flesh tones, and reds.
Well there you have it. You’re now armed with the
basic knowledge to make your TV look its best with the controls you have at your disposal.
...Doug Blackburn
db@hometheatersound.com |
