Optimizing and evaluating new automotive HMI image enhancement algorithms under bright light conditions using display reflectance characteristics

Abstract

Abstract We have developed and investigated new image enhancement (tone mapping) algorithms for automotive Human Machine Interfaces (HMIs) so that displays can be better read in bright light. Our ‘ΔL/L’ approach with adaptive color rendering (CR) is based on Weber's fraction and is easy to use with various displays and illumination variables. In tests with automotive HMIs under different lighting conditions—including driver glare—the ‘ΔL/L + CR’ image enhancement method proved to be a good choice. First, reflective, transflective, and transmissive displays were tested and their image quality compared with and without new tone mapping. It was found that enhancing improved the gray scale perception, even on reflective (e‐paper by dithering) displays. A transmissive LCD, which only reflects monochrome, is highly suitable for mostly monochrome content as it maintains a high contrast ratio under bright light; however, its gamut is degraded at large extent. Transmissive matte LCDs perform best with image enhancement for automotive color HMIs.