Virtual production is now an established technique, but in terms of product development for the space, the industry is still very much in its infancy. Brompton-driven LED screens are often described as the most solid and reliable part of the VP chain, but that doesn’t take away from the fact that most of the equipment being used for virtual production was originally designed with other applications primarily in mind, and that products specifically designed for the application have the potential to offer a lot of value.
LED screens have historically been designed as displays for direct view, with little importance placed on the screen's ability to provide illumination. In VP setups, however, a key benefit is the illumination provided by the LED screen, which helps the actors and foreground scenic elements blend into the virtual environment. Conventional LED screens are not very good at imitating the kind of light produced by natural sources. This light has smooth spectral characteristics, unlike that produced by LED panels, which consists of three spectral spikes — one for red, green and blue. This means that when objects or people are illuminated by this light, some colors don’t look correct – referred to as poor color rendering. While this can be to some extent mitigated by the addition of broad-spectrum conventional lighting, the effect can’t be completely removed. This is also not ideal from a creative workflow perspective — starting from a baseline that looks wrong and having to fix it is far less optimal than starting from something that looks correct and then getting to spend time crafting the look to your creative vision. Unfortunately, one of the things most obviously affected by these color shifts is skin tones, which get shifted unnaturally towards red — not ideal when the screen lights actors!
Adding a broadband (effectively white) emitter to each pixel of the LED panels allows pale colors to be produced with much smoother spectra, which improves color rendering enormously. The LED packages are challenging to manufacture, and maintaining optimal characteristics – for example, consistent viewing angles – is an area of active development. The computation complexity of deriving the drive signal for this fourth emitter, while maintaining per-pixel calibration and color accuracy, is very high, requiring extremely powerful next generation panel receiver cards, like the Brompton G1, to deliver. Adding on controls to allow the spectrum to be adjusted to match the camera response, or for creative reasons, furthers the burden on the control system, but creates the flexibility needed to get the most out of the system. The first LED panels with four emitters will be available in early 2024 – a first generation of products specifically designed to solve problems in virtual production.
The power of next-generation receiver cards will allow for solutions and performance improvements in many areas, with color rendering improvements being an important start.
Adrian Jeakins is Director of Engineering for Brompton Technology (www.bromptontech.com), a West London-based developer and manufacturer of LED processing products.