It was at the movies where we all first encountered a 4K display. Not all digital theaters are 4K today, but many are, with Sony and Christie Digital the leading U.S. suppliers of 4K digital cinema projectors and systems. The theatrical standard for 4K resolution is 4096 x 2160 pixels. For the as yet infant home 4K market, however, the trend is toward 3840 x 2160, or basically double the horizontal and vertical resolution of the best current HD. This is done because a uniform doubling greatly simplifies the upconversion process for regular 1080p full HD to 4K and greatly minimizes the potential for artifacts. That amounts to 8,294,400 pixels, versus the 2,073,600 pixels (maximum) in our current HD format.

Proponents of 4K, which includes virtually all current TV makers, have adopted the Ultra HD moniker to differentiate it from traditional full 1080p HD in the marketplace. It is said to offer significant advantages over crusty old HD. With four times the number of pixels, the pixel structure will be virtually invisible, even when you sit close to a very large screen. Skeptics argue that 4K will be beneficial only in jumbo screen sizes. At 50 inches and under, 4K would not appear to make much sense—either visually or economically. But none of us has yet spent hands-on time with 4K sets in the largest currently popular and affordable consumer sizes. That’s what it will take to judge whether or not there will be any advantage to 4K in, say, a 65-inch set. Stay tuned.

The larger question about 4K is when. Apart from a few short Internet 4K downloads and the output of some video cameras, 4K material must currently be sourced from a computer server loaded with 4K files. Sony provides just such a device to buyers of the XBR-84X900, preloaded with 10 movies plus a variety of shorter material, as an extended loan. The server provided to the earliest buyers will be replaced at some point, and at no charge, with a more flexible design (re-loaded with the same content) to which external storage may be added. Subsequent buyers will receive the new server, also pre-loaded with the initial launch content. Additional downloadable movies will be offered periodically for a yet to be determined charge. Sony has an advantage over other HDTV manufacturers in its ability to offer native 4K material. It owns a major movie studio and is currently engaged in remastering dozens of titles in 4K for possible release in some form. New movies are increasingly being shot digitally in 4K as well.

Ongoing developments in video compression algorithms, specifically the pending rollout of the new HEVC (high-efficiency video coding) standard that will replace the AVC standard now commonly used for Blu-rays, may allow for a new Blu-ray-like player offering 4K movies and other programming on disc (though there’s zero chance that such a format will be compatible with existing Blu-ray players). But at present, there are no publicly announced plans for such a disc format as content providers wrestle with the murky future of packaged media competing against what till now have been inferior but more convenient downloads. A company called RED, which makes professional 4K cameras, has shown a compact, $1,450 Redray server using its own proprietary compression algorithm and is said to be working with a partner to deliver content to consumers. Information on what that might be, however, remains hazy.

Even with 4K streaming or download services being launched, or new disc or other hard media options becoming available, it’s clear that, for a long time to come, the vast majority of content anyone will watch on an Ultra HD display will be upscaled 1080p. As we did with the accompanying review of the Sony XBR-84X900 Ultra HD TV, Home Theater’s evaluations of these displays will continue to pay close attention to the quality and value of that conversion.—TJN