Should you get an HD or UHD display for your  home theater ? There are several things to consider before making this important decision.
1. HD has a pixel resolution of 1920x1080, while UHD (also commonly but inaccurately known as 4K) quadruples the resolution to 3840x2160, but that additional resolution does not offer much visible benefit at typical screen sizes and seating distances. (Of course, you can see a big difference at the "pixel-peeping" distance depicted above, but few people actually sit that close to their TV.)

2. UHD will offer several other enhancements, including high dynamic range (HDR), wider color gamut (WCG), and high frame rate (HFR), but the details are still being worked out. These enhancements will have a much greater impact on image quality than increased resolution.

3. There are several HDR systems vying for acceptance by display manufacturers and content creators, including SMPTE (the only one that's an open industry standard), Dolby Vision, Philips, Technicolor, and BBC.

4. The only currently available consumer displays with HDR and WCG capabilities are the Samsung SUHD TVs, which implement the SMPTE HDR standard; the  Vizio Reference Series will offer WCG and Dolby Vision HDR when it is released, presumably later this year. Also, the  Panasonic  CX850 and Sony X940C LCDs and LG EG9600 OLED are scheduled to get firmware updates that add HDR capabilities—at least for  streaming
 content—this year.

5. There is currently no consumer content with HDR, WCG, or HFR; Disney and Pixar have created HDR/WCG content for commercial cinema using Dolby Vision, and Fox has announced it will produce HDR content for the home market.

6. Streaming services  Amazon , M-Go, Netflix, and Vudu have announced plans to provide HDR content this year, but they could use different HDR systems. Will HDR-capable displays be able to decode multiple types of HDR signals? We don't know yet.

7. The only way to stream UHD content at this point is via the display's  built-in apps , the Sony FMP-X10 UHD server, or the Nvidia Shield streaming box; a Roku UHD streaming box is under development, as are others, I'm sure.

8. Ultra  HD Blu-ray Discs  will support the SMPTE, Dolby Vision, and Philips HDR systems as well as WCG when they—and the players needed to play them—start shipping by the end of this year. Those players should also support UHD streaming, presumably with HDR and WCG if available. To play UHD content with HDR from an outboard device, both the device and display must support HDMI 2.0a.

9. Many people argue that a UHDTV can make HD look much better than it does on an  HDTV , but that depends on the quality of the display's upscaler, and many others maintain that the increased resolution by itself does not improve the picture quality very much at typical screen sizes and seating distances.

10. Because of all the current uncertainty, I generally recommend that mainstream consumers and enthusiasts with limited means wait to buy a UHD display until the dust settles in a year or two. This recommendation does not necessarily apply to fervent  early adopters
 who replace their display every couple of years anyway; in fact, it's because of them that we see so much progress in the development of all consumer-electronics products.