Is 4K a Revolution in Big Budget Movie Production?
4K is becoming the choice for film post production. Some might claim that the reason for this is that the technology is now both fast and affordable enough to make 4K post within the reach of many more budgets. The sceptics will look no further than the DCI’s Digital Cinema System Specification, published in March 2006, which calls for 4K distribution. Although this document does not discuss post production, since the Initiative is the brainchild of many of the major movie studios (Disney, Fox, MGM, Paramount, Sony Pictures Entertainment, Universal and Warner Bros.), it is clearly driving expectations in post as this feeds distribution. Some might argue that it is a little premature, because making real money out of a 4K Digital Intermediate workflow is still a considerable challenge.
This expansion in 4K work from 35mm film shot projects has to be offset by the equal expansion in Digital Cinematography captured projects, the majority of which have been captured at HD resolutions of 1920 x 1080, and posted via a DI workflow at the same resolutions.
So why the rush to 4K? Notwithstanding that you can’t see the full benefit on screen – yet, anyway – there are a number of additional reasons for the 4K migration. As with any improvement in technology, it may be simply that one of them is ‘because it’s there’! Before passing judgment, have a quick look at your cell phone, computer or any other gadget – did you really need to change your trusty old one for the latest new-fangled model? The answer is of course a resounding ‘Yes!’ because that’s human nature…
The reason that 4K has been the standard which so many in the industry have been pushing towards is that it is widely held that 4K is equivalent to the fundamental resolution of original camera negative 35mm film. Thus scanning the OCN at 4K and carrying out the entire DI process at 4K (assuming the signal processing involved is highest quality) will produce a loss-free result, carrying forward all the original detail as it was shot. This has a couple of benefits.
Firstly, effects and composites in particular can look better and more convincing when done at higher resolution – it has been known for some time that material that has been down-converted to SD for the TV version from higher HD or 2K resolutions looks better than if transferred directly to SD on the telecine and posted at SD throughout. It’s all about ‘rounding’ as late as possible in the production chain – gaining the most from Nyquist’s theorem.
However, the rule of diminishing returns means this quality benefit drops off as resolutions increase, making the expense and technological overheads less and less worthwhile as the numbers get bigger...
But for many, the hope is that since a movie will typically be output to multiple formats nowadays (back to film, for digital projection at 2K and 4K, HD, SD, 16:9, 14:9, 4:3 pan and scan, culturally sensitive etc), all of the versions will look the best they possibly can from a 4K original – operational overheads aside.
Secondly, while some would argue that detail beyond 2K is largely wasted in the average viewing environment, on the ‘digital shelf’ it may not be. 4K has the potential to mean that rights owners can return to the movie many years into the future – maybe for reissue or re-editing – and it will still have every detail and nuance of the original (assuming of course that it has been stored on
a digital medium that won’t degrade dramatically within a few years!). Who’s to say that in 10 years time we won’t all have 4K DVD players (or whatever the equivalent then will be!) in our living rooms with massive 4K screens ready for the re-release of Spiderman 17 in all its original 4K glory?! Given that computer-type displays already exceed 2K today, perhaps these are a more
likely candidate for our future home viewing.
But for this scenario to hold true, the whole of the source footage will have to be scanned at 4K, not just the selected takes used for the on-line edit, meaning that the 4K ‘digital shelf’ storage requirement will jump from 8TB to 200TB for a single film for a below average 25:1 shooting ratio.
Just a passing thought - as the ‘digital shelf’ life of any digital medium is far shorter than that of the original source film, which can last for 100s of years if stored correctly, why not simply store the film and re-scan it when and if necessary at whatever resolution and bit depth is required?
But hang on a moment – is 4K really the holy grail? Why limit ourselves to the supposed
fundamental resolution of 35mm film? In parallel with the growth of 4K post, we’re also seeing significant growth in the use of digital capture. At present this is practically limited to (mostly) LOG based 10 bit HD-RGB (1920 x 1080) but 2K’s on the way and there’s no technical reason why the technology can’t grow to 4K and beyond. If things look better at 4K than 2K, then surely they’ll look better still at say 6K or 8K? On the evidence of digital stills cameras, the answer is ‘possibly
yes’ – giving a level of detail that’s beyond ‘photo-real’ – perhaps ‘real-real’ should be our ultimate goal? On the other hand, if you’ve checked out the latest research on resolving power of the human eye with moving images, it could equally be argued that we should just stop at 2K.
And then there’s the issue of film grain – or rather lack of – on perceived image resolution. If images captured via digital cinematography can look so clean at 1920 x 1080, requiring better set building and makeup compared to traditional 35mm shooting, what’s the real requirement for digital film resolutions above 2K?
So just what difference does 4K make to Mr and Mrs Average Movie-Goer? The sad truth is – that’s not what’s driving 4K post production at all! In practice, they simply won’t see much difference because by the time the movie has gone through the normal film optical duplication and distribution process to reach their local cinema, the vast majority of that 4K resolution has disappeared, leaving an image that is not much in excess of 1200 pixels of real resolution. Even Mr and Mrs Media-Industry, who are lucky enough to be able to see the movie projected via a first generation print at a movie premiere in an upscale big-city theater, will still see less than a quarter of the original OCN 4K detail – ie 2K max.
And even those able to see the film projected via the latest in digital theatre projection will be very unlikely to see a true 4K projection – because the projector in question simply won’t be 4K capable – they are very few and far between. In fact, you could argue that to see real benefits from a 4K Digital Intermediate post production and distribution chain you will need to be sitting in an IMAX theatre… where’s your nearest one?
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