Finally painting with light
Posted on Jan 22, 2025
The most recent advancements in lighting tech are not just new toys, but fundamental philosophies and perspectives on the craft
WORDS | Adrian Pennington
The concept of image-based lighting (IBL) is simple: lighting using images. It’s a well-established virtual lighting technique that uses calibrated photographic or videographic RGB colour information to generate subject and environment lighting. Virtual production popularised IBL as a method for motivating light with LED displays, but it’s becoming a more mainstream part of the cinematographer’s arsenal.
“There’s rarely a case in which you can’t use it any more,” explains Tim Kang, principal engineer in imaging applications for lighting vendor Aputure. IBL uses images displayed on LED set lights to produce realistic reflections and ambient lighting in a scene. It gives the cinematographer subtle lighting effects that help make objects appear as though they naturally belong in a given environment. The three main benefits are accuracy, time saving and much more control. “The biggest one for me is control,” says Kang. “We’ve been chasing naturalism in lighting for around 100 years, but we’re only able to approximate an image of the real world.
“With IBL, you can get the naturalism you want and then control the variables and fix them much more directly. The problem is that people still associate this concept with an incredibly niche, expensive LED environment, when in fact IBL is a fundamental lighting philosophy. It involves using any kind of image – like a pattern painted live or a light card – as a lighting source. It also utilises a lighting control methodology that employs an entire environment of lighting fixtures – not merely displays – to generate IBL onto a scene.”
There are now clear technical steps for transforming lighting fixtures into colour-accurate and video-driven lighting pixels. This is why Kang believes the entire craft of entertainment lighting can formally shift its mindset from pixel mapping as a live entertainment effect towards physically – and accurately – executing creatively intentional lighting environments and concepts. “It isn’t very complicated, as long as you’ve got a simple software package and a lighting fixture that understands how to correctly interpret the values. Then it’s just a matter of plug and play. You load the fixture up in your software. You load in your content. You play back the light.
“To enable this, you need to have good data coming in and good data going out. You also need to have the right physics tied to that data.” Aputure has now released tools that take Ethernet data from a video source containing RGB information, translate it into DMX data for lighting control and output that data to all your lights. “Before this, it was extremely expensive. Now, IBL is much more accessible,” Kang says. Light fixtures need to be fully calibrated so that you have got the best spectrum coming out of it for any colour value you throw at it.
“If you want to use a shade of light that’s kind of a cool moonlight, you’re not going to just use red, green and blue diodes alone to simulate that colour. You need to output as much spectrum that matches real moonlight as possible.” The company offers a fixture that is fully tunable for white and incorporates an element of the spectrum that matches daylight sources for more consistent colour responses across all cameras. “Because camera sensors are designed for standard white light (for accurate colour fidelity), the closer you can match the physics of white light, the fewer problems you’ll have in post. It’s as simple as that.”
Each calibrated light fixture has to understand video inputs. One way to do this is to control the lights with a DMX profile. Alternatively, you could use a software like Assimilate Live FX Studio to manage and interpret the video to the correct colour values.
What differentiates IBL from pixel mapping is not only granular control, but the ability to accurately dial in colour that dynamically matches video environments. “While lighting technicians in the event lighting industry only ever need to create the suggestion of a colour (on the stage or a performer), what IBL gives cinematographers is an accurate interpretation of colour space.
“You can use Photoshop-style tools to literally paint onto your fixtures. You can set it to a certain shade of green and instantly see that exact green on-set. You can even use colour grading tools to adjust each fixture’s hue and trim.
“The fact that colour can be painted on fixtures is an absolute dream for gaffers and cinematographers. Most of them see themselves as painters of light. Being able to paint light onto fixtures, as well as change and reset shades and hues, is the ultimate iteration of that.
“That immediacy and granularity is distinct from pixel mapping,” Kang concludes. We have now entered the territory of expression: it’s immediate, it’s dynamic, it’s responsive and that’s what you need in a hectic set environment. IBL really is the future.”
This story appears in the January 2025 issue of Definition
