Things are indeed changing. The 1080p picture quality known by many as “Full HD” isn’t as full as what many once thought, with Sony joining LG in announcing a new 4K TV.

With a measurement of 84 inches diagonal, the Sony’s XBR-84X900 is a big TV for the company, and offers a resolution of 3840×2160, compared to the 1920×1080 normally seen on 1080p TVs. Like the LG announced this week, that’s four times the resolution of a Full HD TV.

Instead of “Full HD”, the new technology is called “Ultra Definition TV” or just UDTV for short, and it’s not the end of picture wars either, with an even more amazing UHDTV or “Ultra High Definition TV” arriving in the years to come.

Like when HD and Full HD were both introduced, the problem with this technology will stem from a lack of content made for this high 4K resolution, especially when people have now mostly caught up with new Full HD TVs.

For the eager early adopters, the Sony 4K TV features the company’s own “4K X-Reality Pro” technology, designed to interpolate and bring Full HD video up to the level where 4K works and looks awesome.

3D is also an area where Sony is making some changes, leaving its active 3D technology and shifting to the more popular passive 3D glasses. The resolution improving technology seen on 2D video will also work here, apparently upscaling 3D videos to the 4K resolution.

We’re keen to see it for ourselves, but Australians shouldn’t have to wait long, with Sony Australia saying that the 84 inch UDTV will be available locally by the end of 2012.