Sony has unveiled a digital cinema projector that can display an image with four times the resolution of a high-definition picture across a 20-metre screen.

The projector, which was used earlier this month to project the ‘Spiderman 3’ movie at its world premiere in Tokyo, is a giant. It stands more than 1.5 metres high, is 1.4 metres deep and 74 centimetres wide and weighs 300g.

At its heart sits a 4.2kW bulb (an average household bulb is about 60W) and light from here is bounced off mirrors and through a prism to be split into red, green and blue streams. Each of these goes through a 1.55in flat-panel display based on Sony's SXRD (Silicon Crystal Display) technology before being combined and magnified through a lens as wide as a man's hand.

The result, as Sony demonstrated today, is a spectacular image that's a rank above what you might be used to seeing at the movies. The projector outputs an image with 4,096 pixels by 2,160 pixels resolution, which is double that of HDTV both horizontally and vertically to result in more than 8 million pixels versus about 2 million on HDTV.

The images shown, drawn from the movie ‘Mystic India’ were crisp and clear, while colours were vibrant. Seeing it for the first time was a similar experience to switching to HDTV after always having watched standard definition television.

Sony is using the rising popularity of HDTV as leverage to sell the system. With high-definition home theatre systems in many a movie buff's home and broadcast HDTV being enjoyed by millions of people, it's becoming more difficult for movie theatres to entice customers based on picture quality. Sony hopes this pinch will push theatres to pay the roughly ¥1.5 million (£6,400) per screen that it costs for the CineAlta 4K system.

For the movie industry, which must be persuaded to invest in higher-quality cameras so they can make movies for the system, Sony is dangling a tasty-looking carrot called security.

At the base of each projector sits a bay that accepts a large 19in rack-mounted box dubbed a ‘media block’. This contains a RAID hard-disk drive array carrying a copy of the movie in JPEG2000 format. The breakdown of security on DVDs has taught the industry the damage that can be done when a digital system is hacked, so on the drives the movie file is encrypted.

A key unique feature for each system is used to decrypt the movie when it is shown and a system built into the projector ensures that the key is deleted should anyone attempt to remove the media block from the projector. In that way, anyone stealing the drives will be left with 300GB of encrypted data, said Sony.

Together the projector, media block and companion software make up the digital cinema system.