| Video Noise December 2005
Your Home-Theater Room:
Considerations for High-Performance Video
The biggest concern for video presentation in a home
theater is light. No matter what type of display you have, it will look its best in a dark
room with a minimum of reflected light. That ideal is hard to achieve in the real world,
but being aware of this goal can help you make better choices for your home theater. The
reflected colors of the walls, ceiling, carpet, and furnishings will skew the color
balance of the images you see on your video display. Direct or reflected white light will
remove detail and contrast. Light sources within the room can degrade video quality a
little or a lot, depending on their location and intensity.
Walls
The best color for walls and trim is flat, velvety black,
but few people are willing to live with it -- including me. Neutral gray walls will
eliminate color contamination from reflected light, though grays reflect more light than
black. If the trim must be white, not much damage will be done to the display’s
image, especially if the window coverings, when drawn, hide all or most of the trim.
Floors
There’s a little more latitude with carpet color
because it doesn’t reflect as much light as the walls, but selecting colors that are
not too bright, and more dark than light, will help optimize picture quality. Here, too,
black is the best choice, though few go that route; choose a carpet color as dark and as
neutral as you can stand. Hard floors, especially those with polished or varnished
surfaces, can reflect a lot of colored light that will affect the video image. At a
minimum, use darker, nonreflecting area rugs around the video display or screen area.
Ceiling
The best ceiling treatment is (surprise!) flat, velvety
black, but that’s unacceptable to most people. It may be necessary to default to
white, just out of convention. White is the worst choice, but if the finish is flat and
the ceiling’s surface has a rough texture, reflected light shouldn’t be too
troublesome. Higher ceilings produce lower levels of reflected light; a white ceiling
9’ or higher won’t do as much damage as a 7.5’ ceiling. Of course, raising
the ceiling increases the volume of the room and may dictate larger speakers and/or
larger, more powerful amplifiers and subwoofers. Home-theater design is an exercise in
tradeoffs.
Furnishings
Like the walls, ceiling, and floors, furnishings can
reflect light. Seating surfaces can be almost anything -- they’ll often be covered by
people, and can easily be covered with a dark blanket when unoccupied. The more dark,
neutral, and nonreflective exposed surfaces are, the more video-friendly they’ll be.
Do what you can within your tolerance limits.
Light control
Other light sources in the room should be carefully
controlled. Window treatments should block as much outside light as possible. If you do
critical viewing during daylight hours, there should be no sources of light between you
and the screen, as these can cause reflections and loss of image detail, depending on the
type of display. Some people even cover the LEDs on cordless phones or other electronic
gear within the line of sight, to prevent light from these sources from affecting the
images.
If room lighting is desired during show time, it should
come from behind the display or screen, and be aimed to illuminate the wall behind
the display so that no light falls directly on the display. This lighting should be
nominally white rather than the yellow you get from dimmed incandescent lamps. A white LED
array is a good way to start white and stay white as you increase the lighting level from
very low to moderate. Because the walls will reflect light from behind the video screen,
the walls should, again, be neutral gray or black rather than something that will
influence the color balance of the image.
The level of such backlighting seems to be least offensive
when it’s a little dimmer than the average brightness of the display -- too bright
and you’ll be distracted from the video images. For my money, you can’t be too
dim -- I prefer no backlight at all. Some people say that without a backlight, their video
displays are too bright and cause eyestrain and headaches, though to me that sounds like
an incorrectly calibrated display. When a display’s white and black levels are
correctly set, the image should not be too bright for comfort in a completely darkened
room. In fact, this is how to achieve the best image possible from your video system.
Needless to say, bright room lighting is incompatible with
high-quality video presentation. If you use your home theater for reading and other
activities requiring more light, those lamps should be turned off during show time.
Can you live with it?
The degree of lighting control I’ve described requires
serious commitment from the home-theater enthusiast. Do as much as you’re comfortable
with and don’t worry that you’re making some huge mistake. Some judicious
choices in décor and color scheme can make a dark, nonreflective home theater a
comfortable living space as well.
...Doug Blackburn
db@hometheatersound.com |
