Improved Definition - Not Just About More Pixels, by Richard Wilding

With the rise of 4k UHD seeming inevitable, Richard Wilding from post production powerhouse, Molinare, shares his experience of 4k workflows. Far from being unworkable, he says, good planning can enable even better creative results.

For Molinare, the 4K story began several years ago. Our first Baselight grading system, which we installed in 2004, was capable of working with 4K images way back then and at the time we proudly put a sign declaring "4K Grading" on the door. Truth be told, 4K work was scarce in those early years – we colour graded some short-form material from 4K film scans but 2K was very much the mainstay for full-length features.

 

Ten years further on, 4K or even higher resolutions are seemingly commonplace – modern digital cameras are constantly developing and increasing pixel count is being touted as a major factor for improved imagery. But improved definition needs more than pixels and that begins with the lens – high quality modern lenses may be deemed good enough to resolve 4K but the artistic use of older lenses or diffusion filters can reduce the captured resolution.

 

Then there is the camera sensor itself – is it really 4K? Bayer pattern sensors are widely used but they make a compromise in not having a red, green and blue value for every pixel site – instead they capture only one colour for each pixel and interpolate the other colours from those around it. So a 4K Bayer sensor captures less than 4K resolution images and, while a 6K or higher Bayer sensor certainly does better, it is not the same as a sensor that captures RGB values for every pixel.

 

That said, what is the impact of 4K on post production? The media files are bigger simply because the pixel count is around four times greater than 2K or HD. The general impact of that is more storage is needed and transfer times are slower for the equivalent duration of media. The ability of systems to playback and process the files is similarly affected, and technically assessing the images at full resolution requires high quality 4K displays and projectors that are currently rare.

 

In practice, this doesn’t mean that 4K is unworkable. Carefully planned storage management can help cope with the increased volume of media, and modern grading and editing systems perform much more smoothly with 4K images than the ground-breaking early Baselight of a decade ago – Molinare’s recently upgraded suites can playback 4K with ease. The increased demands of 4K for playback and storage do ‘rob’ us of some of the gains made by the natural progression of computing power and increasing affordability of data storage but, in time, we will make up that ground again.

 

The recent feature post production on ‘Belle’ was an ideal opportunity for us to trial an end-to-end longform 4K workflow. Ben Smithard, the DoP, choose to shoot on the Sony F65, which has a high resolution Bayer pattern sensor and, although the final delivery was 2K, we opted to undertake the whole post production in 4K to see what the benefits or pitfalls might be. The outcome was that we found that the creative grade was not significantly hampered by the demands of the extra resolution and in some cases the finer detail made it easier to finesse complex grading of scenes. Rendering took longer compared to 2K of course, and the resultant 4K files needed more storage, but the creative process was still fluid.

 

But 4K isn’t just about the cinema experience – it’s coming to our homes too. With TV set manufacturers pushing the sale of domestic 4K displays, and early-adopters, such as Netflix, providing 4K content, the rise of 4K UHD seems inevitable. This may happen regardless of the consumer desire for the higher resolution but it’s not all just about pixel count – higher frame rates, typically 60 fps, are proposed and better image depth too. For many viewers, particularly those without massive screens, those other benefits may be the most appreciable – sport coverage, in particular, may highlight the benefit of improved motion delivered by higher frame rates.

 

So while 2K and HD production remains the mainstream, Molinare has been naturally growing to meet the demands of higher resolution post and we will continue to develop our systems and creative tools to meet the rising tide of 4K production.