Vito Anzalone, far right, looks at the back of Sony's 4K XBR LED televisions at the Sony booth during a news conference Monday in Las Vegas. The 2013 International CES gadget show, the biggest trade show in the Americas, is taking place week.

LAS VEGAS — The race to make TVs larger and larger has created a colossal problem for manufacturers: As screens grow, picture quality worsens — unless the viewer moves farther away from the screen.

The issue is playing out in cozy dens and family rooms around the world. To get the full benefit of a large high-definition screen, viewers must move back from their sets. Because the ideal viewing distance is no closer than three times the height of your screen, or about one and a half times the diagonal length, big TVs have literally forced many families’ backs against the wall.

This year, TV makers are doing their best to give huge-screen fanatics more breathing room. New “ultrahigh-definition” sets were shown off Monday by companies such as LG Electronics, Sharp and Samsung Electronics at the International CES gadget show in Las Vegas.

Consumers tend to buy a new set every seven years or so, and television manufacturers are hoping the technology will give consumers a reason to upgrade.

TV makers are also making their sets smarter. New TVs from Samsung, for instance, will recognize an expanded range of gestures so people can swipe through on-screen menus in a way that revolutionizes the old remote control.

Samsung President Boo-Keun Yoon said the new features are a response to the increased choices consumers have in what they watch.

“We have developed TVs that respond to people’s needs and lifestyles, TVs that know in advance what people want to watch, TVs that have the power to create the ultimate lean-back experience,” Yoon said.

With nearly 8.3 million pixels, an ultrahigh definition screen contains four times more pixels than an HD TV. Because of the higher resolution, viewers can sit close — according to some estimates, as close as the diagonal length of the screen, which is about a third closer than before — without losing clarity. That could be appealing to big-screen fanatics who live in small spaces.

Ultra-HD sets come as small as LG’s latest model, which stretches 55 inches diagonally. And estimated prices are dropping from the tens of thousands to below $10,000, bringing these multi-megapixel TVs well within the spending range of early adopters.

It could be a few years before prices come down enough for the masses to justify buying ultra-HD TVs.