Think your high-definition TV is hot stuff, as sharp as it gets? At the biggest trade show in the Americas, ongoing through Friday in Las Vegas, TV makers will be doing their best to convince you that HDTVs are old hat, and should make room for “Ultra HDTV.”

It’s the latest gambit from an industry struggling with a shift in consumer spending from TVs, PCs and single-purpose devices such as camcorders to small, portable do-it-all gadgets, smartphones and tablets.

The trends suggest that the International CES (formerly the Consumer Electronics Show) is losing its stature as a start-of-the-year showcase for the gadgets that consumers will buy over the next 12 months.

The biggest trendsetter in mobile gadgets industry, Apple Inc., stays away, as it shuns all events it doesn’t organize itself. Apple rival Microsoft Corp. has also scaled back its patronage of the show. For the first time since 1999, Microsoft’s CEO won’t be delivering the kick-off keynote. Qualcomm Inc. has taken over the podium. It’s an important maker of chips that go into cellphones, but not a household name.

None of this seems to matter much to the industry people who go to the show, which is set to be bigger than ever, at least in terms of floor space.

Gary Shapiro, the CEO of the organizing Consumer Electronics Association, expects attendance close to the 156,000 people who turned out last year. That’s pretty much at capacity for Las Vegas, which has about 150,000 hotel rooms. The show doesn’t welcome gawkers: the attendees are executives, purchasing managers, engineers, marketers, journalists and others with connections to the industry.

Though some big names are scaling back or missing, there are many smaller companies clamoring for booth space and a spot in the limelight for a few days. While Apple doesn’t have an official presence at the show, there will be 500 companies displaying Apple accessories in the “iLounge Pavilion.”

Overall, the CES sold a record 1.9 million square feet of floor space (the equivalent of 33 football fields) for this year’s show. Here are some of the themes:

SHARPER TVs

Ultra HDTVs have four times the resolution of HDTVs. While this sounds extreme and unnecessary, you’ve probably already been exposed to projections at this resolution, because it’s used in digital movie theaters. Sony, LG, Westinghouse and others will be at the show with huge flat-panel TVs that bring that experience home, if you have a spare $20,000 or so.

While the sets are eye-catching, they will likely be niche products for years to come, if they ever catch on. They have to be really big — more than 60 inches, measured diagonally — to make the extra resolution really count. Also, there’s no easy way to get movies in UHDTV resolution.

“What’s going to be relevant to consumers at the show is the continued evolution of 3D TVs and Internet-connected TVs,” said Kumu Puri, senior executive with consulting firm Accenture’s Electronics & High-Tech group.

BIGGER PHONES

Unlike TVs, new phones are launched throughout the year, so CES isn’t much of a bellwether for phone trends. But this year, reports point to several super-sized smartphones, with screen bigger than five inches diagonally, making their debut at the show. These phones are so big they can be awkward to hold to the ear, but Samsung’s Galaxy Note series has shown that there’s a market for them. Wags call them “phablets” because they’re almost tablet-sized.

ACROBATIC PCs

Microsoft launched Windows 8 in October, in an attempt to make the PC work more like a tablet. PC makers obliged, with a slew of machines that blend the boundaries. They have touch screens that twist, fold back or detach from the keyboard. None of these seems to be a standout hit so far, but we can expect more experiments to be revealed at the show.

NO HANDS

CES has been a showcase in recent years for technologies that free users from keyboards, mice and buttons. Instead, they rely on cameras and other sophisticated sensors to track the user and interpret gestures and eye movements. Microsoft’s motion-tracking add-on for the Xbox 360 console, the Kinect, has introduced this type of technology to the living room. Startups and big TV makers are now looking to take it further.

For example, Tobii Technology, a Swedish company, is at the show to demonstrate “the world’s first gaze interaction computer peripheral” — basically a camera that tracks where the user is looking on the screen, potentially replacing the mouse.

PointGrab, an Israeli startup, will be showing off software that lets a regular laptop webcam interpret hand movements in the air in front of it.

Assaf Gad, head of marketing at PointGrab, said that CES is usually full of hopeful companies with speculative interaction technologies, “but this year, you can actually see real devices.”