Assessing Color-rendering Differences in Cinematic Lighting with a New Metamer Mismatch Metric

Consistent color-rendering in motion pictures is critical for creating natural scenes that enhance storytelling and don’t distract the audience’s attention. In today’s production environments, it is common to use a wide variety of light sources. Traditional tungsten-halogen sources—red, green, and blue lightemitting diode (RGB LED) sources and white light LEDs—are often mixed, leading to color-rendering issues. This paper introduces a new metric, the Camera Lighting Metamer Index (CLMI), rooted in the concept of metamer mismatching. The CLMI is for assessing the color-rendering differences of disparate sources when a single camera is used and the camera’s spectral sensitivities are known. By leveraging the known spectral sensitivities of the camera and the spectral power distributions (SPDs) of the light sources, CLMI quantifies the potential for color discrepancies between objects lit by the different sources. We propose that this metric can serve as a useful tool for cinematographers and visual effects artists, providing more predictable and precise control over color fidelity. The metric could also be used to supplement existing generalized metrics, such as Spectral Similarity Index (SSI), when detailed camera and light source spectral characteristics are available.