Color Rendering (Optimization of Color Rendering of LED Light Sources Based on Modern Colorimetric Metrics and Adaptive Evaluation Models)

Abstract

The fidelity of color perception under various lighting conditions is crucial in lighting quality assessment. Traditional color rendering metrics, like the Total Color Rendering Index (CRI or Ra) developed by the Commision Internationale l’Eclairage (CIE) in 1964, provide an average measure of color fidelity across a limited set of color samples but do not capture individual color variations. This metric, while widely used, has limitations in predicting color fidelity, especially for specific colors or applications where precise color rendition (such as in skin tones, food items, or particular-colored objects) is essential. That is, this traditional method of evaluating color rendering has a number of limitations, such as using only eight test colors, which is insufficient for a wide range of sources and does not take into account new types of light sources, such as modern LEDs. With the advent of solid-state lighting, especially LEDs, the limitations of CRI became more pronounced, leading to calls for improved metrics. In response, the Society of Lighting Engineers of North America (IESNA) proposed the Color Fidelity Index (Rf), incorporating 99 uniformly distributed color samples and a refined color space to better predict visual color perception. And the color saturation index (Rg). These methods use modern color spaces, such as CIE CAM02-UCS, to increase the accuracy of the work. That is why modern approaches to assessing color rendering will allow us to take into account various types of light sources, including LED ones, ensure the accuracy of transmission where colors are critical and create standards for harmonizing lighting in different industries. The development of these metric systems helps to create better quality light sources and increase the comfort of human color perception. A calculation method was applied, which is determining the deviation of each test color from the reference one under standard lighting and averaging the deviations to obtain the final index. This article explores the fidelity of color indices, compares the efficacy of Ra and Rf metrics, and analyzes their application across various lighting sources, providing insights into the future of color rendering standards.