Moving up a grade7 September 2016
Camera technology is driving and exploiting a demand for ever higher resolution and high dynamic range, expanding creativity on the acquisition side. However the opportunities, and challenges, at the finishing end are also growing.
“We see a lot of grading now in standard television programmes, and there is a very clear push towards more artistic, more filmic look to it,” says Wolfgang Lempp, CEO of FilmLight. “It’s also fed of course by the modern cameras which have fantastic dynamic range, that allow you to play with lighting and grading in a way that wasn’t possible before. And anyone who has seen HDR realises very quickly that is more of a pull for the consumer than Ultra HD.”
“More and more mastering at 4K is taking place outside of DI for theatrical features,” says Simon Bartlett, marketing and business development EMEA for Post Production at SAM. “The main driver for this is the new breed of broadcasters such as Netflix and Amazon commissioning 4K work. 4K HDR will be a natural extension of this and will help up-sell 4K or Ultra HD consumer displays from HD.”
“Although there are challenges, mainly the cost investment and client education, the benefit of both 4K and HDR is increased viewer enjoyment as well as revenue for the post house,” says senior colourist and MD of The Look, Thomas Urbye. “As a colourist, I relish the opportunity to grade in HDR as the contrast range, and in some instances saturation, in REC709 can be restrictive. It’s not all about super sharp, super bright and highly saturated colours, but a more immersive viewing experience by creating visually stunning images. 4K and HDR helps to do that.”
Colourist and colour scientist Dado Valentic is the founder of Mytherapy, and after working on Netflix’s HDR production of Marco Polo, is very well placed to talk about the opportunities and challenges offered by cameras and monitors supporting higher dynamic range and wider colour gamuts.
“HDR is giving us incredible precision in shadows that we didn’t have before,” he says. “HDR screens offer a very high contrast and a larger amount of colour. You can also use much more available light on set. Because we have screens that are now able to display that light sensitivity, we can actually work [on set] more naturally. You don’t have to limit yourself by not being able to display what’s interior and exterior. You can see what’s out through the window.”
“We are able to expose more detail, but also sometimes unwanted detail, and problems that the camera might have captured,” he continues. “Any grading tricks that we were able to get away with in the past are becoming more visible. We have to work with much higher precision.”
The colourist also advises moderation in HDR. “I don’t want people to have their eyes fall out just because of how bright I can make something on the screen. Or skin to look like a cherry, because it can be as red as you want it. It’s more about creating beautiful images, using all the available data.”
Talking specifically about colour
“Before 4K HDR Television, colourists graded in Rec 709 with a 2.2 Gamma curve – it was pretty simple, but now there is more choice and more deliverables.” says Bartlett. “Therefore, the main challenge is not in the grading itself, but understanding the choices you have when working in a specific colour space with an appropriate transfer curve that is required by the different deliverable formats. Otherwise clipping and other artefacts might appear when colours can’t be reproduced on a particular display device. Post production pipelines will also probably need to gear up to efficiently service an increase in 4K demand and also to handle the increased number of deliverables from a 4K HDR master.”
“A lot of customers are playing with HDR, but shy away from it in the end,” says Patrick Morgan, product marketing manager for Digital Vision. “One of the big issues is standardisation – there’s no real [display] standard. The BBC and NHK pushing their Hybrid Log Gamma curve, and you’ve got Dolby pushing PQ [SMPTE 2084].”
“We’ve kind of future proofed ourselves [with Nucoda],” he says. “We’ve been working with DolbyVision for a long time, such as on Pixar’s Inside Out and Disney’s Tomorrowland. We changed our keyer, so that you can key on value as opposed to luminance. We changed our colour curves to be able to work in extended range. We changed our clipping tool, so we can tell it at what level to clip. We’ve got the PQ curve in our matrix. So we did a lot of stuff that people can now use to work in HDR. Standards will make it easier for the customer.”
Thomas Urbye says he has concerns about going from a committed REC709 project to REC2020: “To offer a truly great visual experience I think its necessary to grade for both, grading within the same system and using a special set of highly specialised grading transforms to get from the grade for REC709 to P3 or REC2020 – all signed off by myself and my clients. To just use a simple linear transform seems an unsophisticated and poor approach to the true visual opportunities offered by HDR.”
“Originally when we first started working with HDR, we would receive an SDR grade and repurpose the grade and make it HDR,” recalls Valentic. “I found that was not really giving me the best results. HDR images can look absolutely stunning and beautiful, and just taking an SDR master and stretching it to be HDR is not the way to do it. The best way for me was actually to grade in HDR and create a SDR master in parallel.”
Valentic developed his own tools for this, which he integrated into Blackmagic’s Da Vinci Resolve. It addressed practical concerns too.
“Just because we are delivering in HDR, it doesn’t mean we get extra time to do it,” he says. “Productions are not necessarily going to bankroll the upgrade to HDR. They want it delivered in the same time frame, and the same budget.”
Keeping up with colourists
Among the pre-NAB news we’ve seen is the new release of a toolset in Colorfront’s Transkoder 2016, which the company claims offers a way to output simultaneous, real-time grades on 4K 60p material to HDR 2084 PQ Rec2020 and Rec709 for SDR.
SAM has redesigned Quantel Rio to take advantage of 4K HDR. According to Simon Bartlett, this entails “wide colour gamut support, native colour space on disk , high dynamic range transfer curve support and 32-bit full float / 16-bit half float processing.”
Baselight 5.0, released by Filmlight for NAB, introduces a host of tools, including Base Grade, a set of controls which mimic the way the eye appreciates colour, via exposure, temperature and balance.
“It’s specifically there to deal with high dynamic range images in a natural ways,” says Wolfgang Lempp. “It’s a more photographic approach, rather than the conventional video based approach of Lift, Gamma, Gain. There’s also a lot of work that we’ve done behind the scenes in terms of colour management.”
Baselight 5.0 provides gamut optimisation to provide natural gamut mapping for deliverables and avoid clipping, as well as colour space ‘families’ – which aims to simplify the deliverables process for distinct viewing environments such as television, 4K projection and handheld devices.
Holistic thinking in colour
“One of the really important things for us, and it’s particularly true for television, is productivity,” says Lempp. “That’s why we’ve always pushed this idea that we should start grading early. There’s a lot you can do on set, or as part of post production and visual effects, if there is consistent way of viewing colour.”
Mytherapy follows a colour managed workflow, working with the DoP before shooting starts.
“We develop what we call a show LUT,” says Valentic. “We can track the metadata for the looks that were implemented on set to the grading suite, so when I conform, I don’t just conform the picture and sound, I also conform the colour metadata as well. I’m not inventing and creating a look at the end of the job.”
“I wouldn’t do HDR in any other way,” he adds. “I really do not want to do a job where it’s just shot and given to me for grading – that’s almost like rescuing something. In HDR we have to know what we’re getting, when they shoot it.”
Confirming Lempp’s observation, Valentic says his biggest bugbear is time: “To the producers, if you’re going to be working in HDR, give us more time. It’s not necessarily that we are slow in working with HDR, it’s just that we need to be more precise in what we’re doing, and that needs more attention to detail.”
By Thomas Urbye, The Look