HDR Lighting Dilation for Dynamic Range Reduction on Virtual Production Stages

TL;DR

This paper introduces a method to reduce the dynamic range of HDRI environment maps for virtual production by dilating bright regions, preserving energy, and minimizing light spread for better display on limited-range lighting systems.

Contribution

A novel technique for dynamic range reduction in HDRI maps that preserves energy and minimizes light spread, suitable for virtual production environments.

Findings

Effective dynamic range reduction while conserving energy

Prevents chromatic fringing in the resulting illumination

Applicable to virtual production LED stages

Abstract

We present a technique to reduce the dynamic range of an HDRI lighting environment map in an efficient, energy-preserving manner by spreading out the light of concentrated light sources. This allows us to display a reasonable approximation of the illumination of an HDRI map in a lighting reproduction system with limited dynamic range such as virtual production LED Stage. The technique identifies regions of the HDRI map above a given pixel threshold, dilates these regions until the average pixel value within each is below the threshold, and finally replaces each dilated region's pixels with the region's average pixel value. The new HDRI map contains the same energy as the original, spreads the light as little as possible, and avoids chromatic fringing.