First, there was high-definition TV. Now there's ultra-high-definition (UHD) TV. A number of display and TV manufacturers, from Samsung and LG to Westinghouse and Sharp, will be showing off new UHD TVs in Las Vegas, and some of them will be very big (both Samsung and Westinghouse are rumored to have 110-inch models coming). So what's the big difference? Higher resolutions. Much higher, in fact. A 4K UHD TV supports a 3,840 x 2,160 display resolution, which is four times the resolution of regular HD (hence the 4K moniker). An 8K model, meanwhile, supports a 7,680 × 4,320 resolution, or eight times what regular HD offers.