Brompton Technology demonstrated their new TrueLight calibration system at NAB 2023. Driven by the company’s new Tessera G1 receiver card, TrueLight can achieve a full calibration of all pixels and control of the broader spectral output from new types of LED panel that include diodes emitting a colour outside the standard RGB format. This extended light spectrum gives more accurate colour rendering, illuminating people and sets more realistically.

Attendees viewed TrueLight in action during demos at the Show, made in collaboration with ROE Visual who showed their new Carbon 5 RGBW panel running on TrueLight, with the Brompton Tessera processor. TrueLight uses Brompton's proprietary Dynamic Calibration for spectral measurement, performed by the company’s Hydra measurement system.

Spectral Output

Measuring spectral output of a light source involves observing and measuring each of the wavelengths that it emits. Spectral output is defined as the intensity of light at each wavelength, over the complete range of wavelengths emitted by the light source. This spectral power distribution is like a fingerprint of a light source, and indicates how it renders colours.

Brompton’s combined measurement/calibration system is capable of complete spectrally-aware calibration for the new non-standard emitters to ensure colorimetric precision, full colour and luminance correction are applied on a per-pixel basis, delivering the image quality necessary for direct-view applications, including reflections. All possible RGBW spectral mixes are fully corrected, maintaining calibration accuracy at all times.

Dynamic Calibration

Dynamic Calibration maintains uniformity and takes full advantage of LEDs to improve brightness and colour saturation. Traditionally, a fixed, factory-specified calibration is applied and used for all content over the entire life of the panel, which may result in panels performing below the brightness they are capable of.

Dynamic Calibration is a more flexible approach, using the Tessera R2 receiver card’s Dynamic Engine to process image and hardware information in real-time to intelligently determine the best possible way to drive each LED. The resulting adaptive panel performance aims to achieve brighter whites and improve contrast ratios, colour saturation and colour accuracy for better image depth and realism.

For example the extremely bright areas of video content can use the LEDs’ full brightness to increase visual impact and, leaning on colour accuracy, the more subtle areas of content like skin tones are carefully balanced for a lifelike effect. In areas of vivid colour, Dynamic Calibration adapts to use the maximum available gamut of the LEDs.

Beyond the automation, the dynamic nature of the system means brightness, primary colours and white point are always user-adjustable. Also, should recalibration be necessary, it can now be done at any time from the DynaCal UI on Tessera processors. Changes show in real-time on the screen, even during a live event. This level of interactivity encourages experimentation and more deliberate choice of colour and brightness. Zebra indicators can be enabled to highlight areas of the image that are pushing the LEDs beyond their peak brightness or colour gamut, helping the user to quickly fine-tune the diodes.

DynaCal interface for re-calibration

ROE Carbon 5 RGBW Panel

The ROE Carbon 5 RGBW is one of the first of the new type of panel, calibrated by Hydra to make the panel's fourth emitter colour available, outputting a broad spectrum white. “Users can dynamically adapt the spectral behaviour using controls in the TrueLight processor UI, including optionally disabling the ‘W’ LEDs for conventional fully-calibrated RGB-only operation,” said Cesar Caceres, Brompton's Product Lead.

Using many of the software features of the Tessera processors, TrueLight takes advantage of PureTone for consistent linearity of both RGB and ‘W’ LED output, ThermaCal for temperature correction of all LED colours, ShutterSync to eliminate on-camera artifacts for RGBW lighting and direct-view applications, and Extended Bit Depth to enhance the dynamic range of RGBW output, among others.

Chris Deighton, Brompton's CTO, commented, "There has been increasing interest in broader spectral output from LED panels, and we aimed to meet this demand without compromising the existing levels of image quality and flexibility in Brompton equipment.

“The processing power available in the G1 receiver card means TrueLight can perform spectrally-aware full-colour per-pixel calibration of all four RGBW LED colours, with fully dynamic controls to adapt the spectral behaviour in real-time. We're looking forward to seeing how the industry adopts this technology to achieve ever more realistic in-camera visual effects." www.bromptontech.com