Hue-Preserving Color Transforms for LED Wall Virtual Production Workflows

Virtual production using light-emitting diode (LED) wall display technology is gaining popularity in the entertainment industry to produce motion pictures, episodic television, live broadcast, and esports content. This new paradigm typically uses one or more large LED displays that contain millions of individual LEDs that are used to display a virtual background and/or foreground objects from a virtual scene that is simultaneously captured by the digital photographic camera on set, resulting in the so-called “in-camera visual effects.” In a virtual production workflow, digital cameras capture the actors and objects on the set in the foreground while simultaneously capturing the image shown on the LED wall behind the actors. Realtime video game rendering engines update the image shown on the LED wall to compensate for changes in camera location, camera pose, and lens focal length. Modern digital camera workflows typically include color transforms that were not designed to accurately render the large areas of saturated colors that are possible when capturing the image shown on an LED wall. Some examples of a hue shift that can occur in typical workflows are blue to cyan, red to pink, red to orange, and green to yellow. We found that these hue shifts can occur dynamically while racking focus to and from the LED wall and also statically when the LED wall is kept out of focus, which is a common technique that is used to minimize moiré artifacts. This article explores a simple modification of these common color transforms to preserve the hue of the scene while also creating a similar look to the existing color transforms.