IBC
The digital cinema conference sessions at IBC are dominated by discussion of High Dynamic Range (HDR), a means of augmenting the picture quality of content shown theatrically and in the home.
“The HDR revolution has shaken a lot of folk in the industry to be aware of the fidelity of their image,” says Dominic Glynn, Senior Scientist, Pixar. “It's a wake up call for those skating a fine line of efficiencies and short cuts to better protect their imagery throughout the pipeline if they want to leverage HDR into distribution.”
While it has long been possible to record the full dynamic range from light onto film stock, and more recently on digital image sensors, what has not been possible is a way of preserving that information through to final display.
A number of techniques and technologies have now aligned to enable this. At the display end this includes HDR-enabled Ultra HD TV sets which can decode and present higher brightness imagery. These will pour into shops at Christmas. Laser projectors deliver the necessary uplift in luminance for cinemas.
“For most of the past thirty years in CGI and VFX it was only possible to display a limited range of light values for images,” says Rick Sayre who worked with Glynn to create the HDR finish for ‘Inside Out’. “By convention we picked 1.0 for the brightest value we could make, and accepted that 0.0 wasn’t really black. Now, with the new high dynamic range displays, we can begin to talk about images as a photographer would - in terms of contrast, mid greys and tonal structure. Not only VFX elements and light probes, but finally the images the audience will see can move beyond that 0 to 1 range.”
Unlike the current migration to 4K and Ultra HD, the addition of HDR does not incur a huge knock-on cost in data handling. “Improving the pixel has a much lower incremental cost than making more of them,” he observes. “More pixels cost more to render but better pixels require more care.”
However, just a handful of cinemas worldwide have the necessary equipment to showcase HDR. It is an expensive proposition for exhibitors who have only just finalised migration to digital projectors. For the time being, laser-projected HDR will be the preserve of flagship auditoria known in the trade as Premium Large Format.
“Our hope is that HDR is a broadly proliferated platform,” says Glynn. “We recognise the economics involved and that right now this is bleeding edge. HDR speaks to premium exhibition.”
HDR for the home though is another matter. Hollywood studios are packaging catalogue and new titles (like ‘The Lego Movie’) with an HDR sheen.
Outside broadcaster tech teams are busy testing ways of transmitting HDR from the lens to the screen where HDR would lift the picture quality of sunlit or shadowed sports from football to cricket. HDR can also render visibly better HD picture too.
But there are issues which the IBC sessions will help thrash out. The main one is the lack of a standard formulation for the format. How bright should the whites be? How dark should the blacks be? Is additional training for colourists required? How much will HDR-enabled production kit (monitors, projectors, grading pipelines) cost?
It will also add complexity to mastering. Potentially separate HDR and SDR (normal or standard dynamic range) versions, and even individual masters for proprietary HDR formats from Dolby, Imax or Technicolor may be necessary. There is pressure on all sides to limit the number of source masters, one for TV and one DCI-compliant.
It is notable that BBC R&D is being honoured by IBC for a novel solution to the delivery and display of Ultra HD and HDR video for their technical paper “A display independent high dynamic range television system.”
HDR may “open up a window into a world we put so much time effort and love into,” for ILM's Image Pipeline Lead, Jeroen Schulte, yet the full creative implications have to be explored.
"We don't know yet what it means to light for HDR,” suggests Sayre. “You can show the audience [detail they wouldn't have seen before]. The question is whether you should, in terms of the story. We need to beware of gimmicks.”
“It's a high impact return for creatives,” asserts Glynn. “It affords a visceral yet subconscious feel for an audience. You don't need to read a white paper to understand that HDR enables higher quality filmmaking.”
Rick Sayre, Dominic Glynn and Jeroen Schulte give the IBC Big Screen keynote: ‘Extending the creative palette - Vision from Pixar and ILM.’
Note also three sessions on HDR: From zero to infinity which feature expert contributions from Curtis Clarke, and executives from Imax, Barco, Dolby, Sony Pictures and more.
Andrew Cotton and Tim Borer, authors of the BBC R&D paper will present it at 14:00 on Friday 11 September and receive their award at the IBC Awards on Sunday 13 September.
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