THE PROS AND CONS OF LED SCREENS AS GREEN SCREEN REPLACEMENT

New virtual production methods using LED walls as backdrops for filming are still comparatively new, but there are many great benefits that may mean traditional green screens become a thing of the past. Of course, as with any new technology there are also some shortcomings and pitfalls. We’ll talk through them all in this blog.

Some of the pros of using LED walls instead of traditional green screens:

• • Capture VFX in-camera
    • Directors and DOPs can now see the full picture through the lens, live on set, and work with the technical team to make real-time adjustments pre-shooting

• • Realistic reflections
    • Previously the bane of post-production, now reflections are immediately accurately captured on set, reflecting the “world” around the actors on all set and costumes

• • Realistic ambient lighting
    • LED panels deliver dynamic and nuanced coloured light, creating a much more lifelike environment to be captured in camera, saving time in grading later on

• • Ease time pressure on-set
    • Capture perfect outdoor lighting in the real world, and have it on-set for as many hours as needed in a controlled environment

• • Immersive on-set experience
    • Create a seamless blend of physical set with pre-shot or VFX environments, so that for the first time actors and the creative team can see and react to a CGI world in real time

• Shorter post-production time
  • Most of the CGI work is done pre-shooting, and the realistic lighting and reflections mean the post-production process is considerably streamlined

And some cons you might not be aware of:

• • Can be expensive
    • Depending on the scope of the shoot, LED green screen replacement can be expensive, involving several LED panels and a quality LED processor to ensure you don’t run into any of the other issues listed below

• • Camera picking up moiré
    • Keeping the screen separated from the foreground and ensuring a suitably shallow depth of field is essential to avoid unsightly moiré effects

• • Visual artefacts
    • It is possible to get interactions between particular camera technology and the refresh patters of LED screens, which can be unexpected (such as the potential for scan mux lines when a camera is tilted up or down)

• • Dropped or doubled frames
    • Poor quality processing without proper genlocking can cause issues with sync between the screens and the camera’s shutter

• • Latency
    • If using the LED screen as part of a virtual production setup using camera tracking, you need a powerful processor capable of extremely low latency, otherwise the footage on the screen won’t sync with the movements of the camera

• • Colour accuracy
    • Cameras sense colour differently to the human eye, so it is important that your processing provides the required level of colour accuracy and the tools to tweak the colour output

• Careful set lighting
  • Traditional set lighting needs to be adapted to balance with the emissive lighting coming from the LED screen, as well as minimising light spill onto any screen surfaces

The best news here is that most of the cons of replacing green screens with LED screens can be overcome with careful planning, diligent camera tests pre-shoot, and – crucially – quality LED screens with powerful processing behind them.

Brompton has a team of technical support engineers who are highly experienced with setups using LED screens as green screen replacements for virtual studios and virtual production on film and TV sets. If you’d like to know more, get in touch at: info@bromptontech.com