Many volumes have LED ceilings or flanking walls that will never be in shot but are there solely to contribute to the lighting of a scene. The realistic reflections and lighting the LED panels provide are a crucial element in achieving realistic in-camera visual effects.
The problem we face with RGB panels as a light source, however, is that the spectral output of RGB is poor for colour-rendition, leading to colour shifts and unnatural skin tones. But adding an additional emitter, such as white, to an LED panel provides a broader spectrum with light output across all wavelengths, so skin tones look natural and colour shifts are avoided, ensuring better blending of any lit foreground elements with the virtual background.
In this image, you can see how different some colours look when illuminated by RGB vs. RGBW. Here, two images of the same colour checker chart have been combined. The circles in the centre of each block show what it looked like under illumination from RGB, and the outside shows what it looked like under illumination from RGBW. You can see significant colour shifts affecting colours in the yellow-orange range.
Here we do the same test with a model, and you can clearly see how skin tones look flushed under RGB, but more natural under RGBW.
The challenge is maintaining per-pixel colour accuracy and having user control of the conversion from RGB to RGBW. This is what Brompton’s new TrueLight® technology delivers.
We’ll look at these challenges and more in upcoming blogs in our ‘panels and lighting’ series.