Optimizing HUD-EVS Readability: Effects of Hue, Saturation and Lightness on Information Recognition

Enhanced Vision System (EVS) offers a display advantage that conventional devices lack, enabling interface information to be overlaid on real-world imagery. However, information overload, especially in complex environments, can reduce the recognizability of important information and impair decision-making. This study investigates a dual color-coding strategy to optimize the recognizability of Primary Information (PI) and Secondary Information (SI) in Head-Up Display–Enhanced Vision System (HUD-EVS) against complex backgrounds. The results show that adjusting the hue, saturation, and lightness of SI affects the recognizability of both PI and SI. Specifically, certain saturation (20% or 80%) and lightness (60%) combinations should be avoided to ensure PI prominence and maintain sufficient recognizability for SI. These findings provide insights for designing color-coding strategies for EVS, enhancing the recognizability of information on mobile devices.