Sony chose a rainy afternoon in downtown Tokyo today to unveil a revolution in digital cinema - a projector that can show full cinema-size movies at four times the resolution of standard high definition, with an anti-piracy server system on the side.

The ¥15 million (£63,280) SRX-R220 CineAlta 4K digital projection system projects almost 9 million pixels in a 4096 x 2160 arrangement, giving it four times as many dots as a 1920 x 1080 HD TV.

HD TV driving progress

Naturally, a projector like this isn't meant for the home enthusiast - Sony hopes to sell it to Japan's cinemas and to have it in 1,000 screens by 2010. The inexorable progress of HD TV into the home has inevitably raised the bar of consumer expectation when it comes to picture quality, leaving the CineAlta 4K in prime position to meet those sales targets.

The projector has plenty of high-end technology powering its 20m-wide ultra high-definition displays. A 4.2kW bulb provides the light source, while mirrors, a prism and something Sony calls a 'Silicon X-tal Reflective Display' deliver the images to the screen.

Other 4K digital projectors have been on Sony's catalogue for a couple of years now, but have been unsuccessful due to the lack of protection provided against piracy.

Encrypted movies

To that end, the high price also includes a rack of RAID hard drives known as a 'media block' that hold the films to be project in encrypted form. The JPEG2000 -encoded flicks are decrypted by a key unique to each projector only when needed in an effort to stop would-be pirates simply walking off with the hard drives.

To make use of them, it would be necessary to take the 300kg projector along too, which could prove tricky. Still, there's nothing to stop ne'er-do-wells sneaking in a high-definition camcorder and taking their chances with the powers that be.