Marcello Luzi calls it the neglected sixth plane. The reason: Few people do anything interesting to their ceilings beyond choosing their favorite shade of white.

Yet little by little, design is creeping over the cut-in, at least in homes where artistic-minded people dwell. Luzi, of Weixler Peterson Luzi in Philadelphia, said he is seeing more coffered ceilings. Miriam Ansell, who owns Miriam Ansell Interiors of New Hope and New York, says at least a quarter of her customers are adding molding, color, paper, or decorative painting. More people are opening their minds to the possibilities, Luzi said, possibly because they watch interior design shows such as those on HGTV, which have turned the cameras atilt.

But no one is seeing a definitive trend, much to these designers' chagrin. "I'd like to make it a trend. I have a personal battle with the public," said Luzi, adding that he constantly preaches ceiling design to his students at Drexel University.

To these pros, leaving the ceiling out of the design scheme is unconscionable. Whether you're a pro or a DIYer, at least acknowledge it's worth more than a roller or two of white, they said.

"Think of the room as a container, integrating all surfaces," said Caroline Millett, of Millett Design in Philadelphia. "The ceiling is by far the most important in some rooms, like a spiral staircase . . . [or] a powder room. When someone sits on the toilet, the ceiling becomes important. Wallpaper it."

Heck, it might save you all that cutting-in time.

That said, it doesn't mean the ceiling always should be decorated, said Ansell.

"It depends on a lot of things, like the style of the room, the height of the ceiling. Do you want to bring it down? Make it farther away?" You need reasons, she said.

Barbara Voltz, of West Chester, found a slew of them when remodeling her Georgian Revival a few years ago. In the front hallway, the beams were not centered, so she and her husband made them look so with recessed drywall. In the dining room, the Voltzes solved an electricity-access issue by attaching the three chandeliers to decorative boxes that hid the wiring. In the kitchen, the ceiling is coffered because "you are walking in low and you want to bring the eye up," she said. Her dining room ceiling is painted charcoal to match the walls.

Of her finished ceilings: "It's like you didn't forget something."

Our European ancestors never forgot to look up. Their high-as-the-sky palazzo and church ceilings demanded attention. Go to a country house in England, Luzi said, and the ceiling is treated like the floor. Until the 20th century, Millett said, U.S. architects paid attention to height; there were grand ceremonial rooms, and hence decorated ceilings. But you won't see that in condos today.

Or in a Mayfair rowhouse.

But owning a modern-day home is no excuse to ignore the sixth plane, Luzi said. "The idea is, go ahead and treat it."

For example, paint. Ansell painted the ceiling and walls in a New York apartment an amethyst hue so the eye could focus on the fixtures in the apartment.

Millett said the lighter the color - save for white - the higher the ceiling will appear.

If you paint the ceiling with a high-gloss light blue, it will appear high like the sky. Use a matte finish if your ceiling is too high; it will make it appear lower. What you do to a ceiling can address problems of scale and proportion, too, says Millett.

When Ansell was designing a small kitchen with a tray ceiling, she papered all five planes with the same tomato-soup-colored paper.

"I didn't want to chop [the room] up. This way, you're only looking at the tomato color and not seeing a million different things in a small room."

How about seeing a million different designs on the ceiling? Holly Fisher, of Media, specializes in hanging wallpaper, particularly from the Victorian period. It's not unusual for her to hang multiple patterns on a ceiling, which she applies with ladders and planks - no scaffolds. (It's the first piece that's the killer, she said, just trying to get it straight across the ceiling.)

If paper and paint aren't interesting enough for you, try:

Putting in a skylight. "It creates an enormous visual difference," said Millett. "Yes, you're talking money, but boy do you have magic."

Removing the ceilings. Your too-low ceilings become higher, Millett said, and then you can paint the ductwork and exposed wires.

Changing your lighting. Buy four torchieres, or floor lamps, and put them in the corners, to make your ceiling higher; curve them down to make the look lower, said Millett.

Installing beams or planks.

Applying silver leaf paper. It will add "drama and bling," Luzi said.

Decorative molding is also an option, which Ansell used to redesign a South Brunswick couple's bedroom and sitting room. She wanted the rooms to at once look like they were one, but separate. By applying molding on the sitting room ceiling, she was able to establish the two rooms that were united with creams and café au lait colors.

If you don't feel confident with your ceiling skills, there's always professional help. Said Luzi: "Designers are really handy. We are thinking."