GIZMO: The home theater, reimagined.

In an era of no-money-down, devoting one of the many rooms in your McMansion to a home theater seemed like a cool idea. But these days, people are downsizing their residences and expectations.

At last week's CEDIA (Custom Electronic Design & Installation Association) trade show, companies like Optoma and Stewart Filmscreen pitched new products designed for the "multipurpose room."

That's a space which starts out as the living room, den or family room. Then, with a little magical tweaking and incantations of "lights, camera and action," the room transforms into a wondrous environment for viewing movies and sporting events.

Let's look at some of the new tricks of the trade you can use to work this conversion.

PROJECTOR PALS: What costs about the same as a 40-inch, flat-panel TV yet displays a high-definition image nine times larger, delivering a walloping 120 inches of big-picture pleasure?

Answer: the latest generation of high-definition video projectors, now selling for a fraction of what predecessors (or a wacky expensive 100-plus-inch flat panel) would set you back.

One of the best deals around is the Optoma HD65 720p (720 lines, progressively scanned) picture maker, priced at $699. And I've been testing the new Optoma HD20 DLP Home Theater Projector, the first to deliver full HD 1080p pictures for a "mere" $999.

Connected to an equally high-resolution video source (like a Blu-ray player) and external sound system, this show maker delivers pictures with unbelievable "wow" factor - palpably real, color accurate and pretty darned bright.

With its "short throw" zoom lens and "offset image" projection technology, the HD20 can be placed on a coffee table or hung tight to a standard, 8-foot ceiling.

Positioned 8 1/2 feet from a screen (or white wall), the Optoma's zoom lens throws a staggering 80-inch diagonal, 16x9 image. Set up 16 feet from the viewing wall, the smallest image it projects is 120 inches!

The Optoma's HD image isn't quite as razor sharp as that produced by my standby, 3 LCD panel-based Mitsubishi HC4900, the first 1080p video projector to break the $2,000 barrier a couple years ago and a model praised for superior optics. But I'm thinking only the eagle-eyed would notice the difference.

Mitsubishi also was at CEDIA announcing a new, "budget minded" 1080p DLP-based projector, the HC3800, carrying a $1,495 suggested retail price. True to Mits' tradition, this model boast an extra-long capacity, 5,000-hour lightbulb and whisper-quiet fan. (The Optoma bulb is rated for 4,000 hours use, and its fan whirl is mildly noticeable until you crank up the sound.)

Epson announced a "budget in mind" 3 LCD 1080p projector at CEDIA, the PowerLite HomeCinema 8100, likewise to be launched at an "affordable" $1,499 (after $100 rebate).

SCREEN TEST: Prized by filmmakers, exhibitors and home theater aficionados for its products, Stewart Filmscreen makes state-of-the-art movie/video display screens for all sizes and applications.

You can get 'em flat or curved, small or large, in reference-standard neutral white (StudioTek) and gray-toned (FireHawk and GrayHawk) surface finishes. The latter vastly improves the contrast and black performance of DLP and LCD-based projectors like those mentioned above, without perceptibly darkening the image in the "high gain" FireHawk G3's case.

But Stewart has come to realize that its big screens sometimes have to play second fiddle in today's multipurpose room, explained company exec Don Stewart. In a recent demo, he showed how this would play out.

A wall-mounted flat-panel TV was on, showing a news program. Then, for prime-time viewing, a button on a remote control triggered a huge screen - hidden behind custom aluminum trim resembling a wall soffit - to float down in front of the flat panel. Turn on the front projector and it's show time!

Branded "Americana," this new, motorized Stewart screen is available with optional LED strip lighting that backlights the image, as eye doctors recommend, to reduce viewer eyestrain without spilling unnecessary light on the picture.

Another new Stewart product to fine-tune your multipurpose room is the AcousticShade motorized shading system.

Press a button and the three-ply window shades drop down, not just blacking out exterior light but also seriously dampening outside noise as well as unwanted inside resonance.

Stewart's stuff is pricey. Just one of the fixed-mount, black-velvet-framed, 100-inch screens goes for close to two grand.

But as this stuff magically transforms a room without building on an addition, you're getting plenty of bang (and zap! and pow!) for the bucks.

LET THERE BE LIGHT: Happy with your big-screen TV and sound setup but hankering for more movie theater-like ambience?

Lutron Electronics' RadioRA-SR system could be your ticket. Running with special radio frequency technology and thus easily installed without new wiring, this one-room control system lets you dim the lights to preset modes such as "preshow" (half-bright) or "feature time" (near or full blackout).

With added components, the Lutron system triggers motorized curtains to part (revealing a hidden TV screen) or close (to darken the room). And the whole show can be steered with a remote control that also operates audio/video gear. A RadioRA-SR starter system goes for $850.

E-mail Jonathan Takiff at takiffj@phillynews.com.