The idea of the display technology being a choice, rather than a given is important, because the technology being used to present 3D in the home isn't actually as important as the technology being used to carry and distribute it. This is where standardisation will be vital, lest any opportunity for 3D be squandered in yet another ugly format war. As always, however, there is some contention as to what this standard might end up being.

To start with, Panasonic's sequential 3D display technology runs hand in hand with a technology designed to store 3D content as sequential frames using the bandwidth and capacity of Blu-ray disk. This isn't particularly complicated and Panasonic's Hollywood technology arm has already developed a mastering technology, but it does require changes to the Blu-ray specification and to Blu-ray hardware. Tellingly, while Panasonic's demonstration 3D hardware - a Panasonic Blu-ray player, 103in plasma screen and XpanD 3D glasses - is adapted from off-the-shelf kit, Panasonic can't currently go into details about what exactly those adaptations entail. Certainly, you won't be able to run 3D content in Panasonic's format on an existing Blu-ray player, and there may well be changes needed to the HDMI specification too. On the plus side, it's possible that existing 1080p plasma and LCD screens may be compatible, provided they can operate at 120Hz. Panasonic plans to push its 3D standard to the Blu-ray consortium this year, with the aim being to release 3D hardware as early as next year.

Philips, predictably, has a rival format. Its system is based on the existing MPEG standards, but with an added channel for depth. In many respects, this isn't a huge departure from the TriDef format being used to power existing 3D ready screens from a PC. Currently, even Philips' 2D plus depth format only runs through a Windows PC, but there are plans to move it to consumer electronics and allow tricks like a real-time stereo camera to 2D plus depth conversion for live shows and sporting events, and eventually on-the-fly 2D to 3D conversion.

Dolby's proposed approach offers a credible alternative. It relies on an interlaced 3D image, with the two component images of the stereoscopic image arranged as two 'checkerboards' of pixels on the same screen, the 50 per cent loss of actual resolution being perceived as a more acceptable 30 per cent loss in practice. Other companies, notably Mitsubishi with its 3D technology, have tried this before, but where Dolby has been clever is in getting this checkerboard system to work and compress efficiently within the existing H.264 format - a considerable feat given that the whole basis of video compression is that neighbouring pixels correlate closely to each other, rather than separate out into different views.

The upshot of this is that Dolby's system is compliant with existing Blu-ray players, the existing HDMI standard, and indeed anything that can carry or transmit an H.264 stream. The only stipulation is that there needs to be a 3D display at the end of the chain to present the two views, though the system is actually agnostic as to what kind of display is actually used. Either sequential/active shutter glasses systems, polarized/passive glasses systems or lenticular displays should work fine. In fact, Dolby has demonstrated its technology with a range of off-the-shelf displays.

Hyundai has had a 46in 3D LCD TV based on a polarization system on sale in Japan since April last year.


Again, all these formats have their advantages and trade-offs. Panasonic is proud of the fact that its system presents full 3D in full HD, but will consumers who have bought into HD screens and Blu-ray players be willing to invest in new equipment just to play 3D content? On the other hand, while the backwards compatibility of the Dolby system is a huge plus, some might see the drop in resolution as an issue. Dolby's Senior Product Manager for Consumer Electronics, Matthew Chang assured me that the company is "looking for an experience that's consistent with Blu-ray" but we'll have to see the pudding before we get the proof.

At the moment, nobody knows which way this one will go. Currently, there are at least three industry bodies - the Consumer Electronics Association, the 3D Task Force of the Society of Motion Picture and Television Engineers and the 3D@Home Consortium - all trying to establish a working 3D standard, and that's without groups like MPEG and the Blu-ray consortium getting involved. One thing, however, is for sure: nobody in the consumer electronics industry wants to see a repeat of the ugly Blu-ray vs HD DVD debacle, so we can expect a working standard before hardware - and particularly software - hits the market.

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