Image-based analysis of electrochromic materials: Gamma correction with a LEGO luminance checker

Abstract

This study explores the use of smartphone RGB cameras for reflectance measurements in electrochromic systems, using tungsten trioxide (WO₃) electrodes. The work highlights the challenges and inaccuracies introduced by gamma correction. While gamma correction enhances image aesthetics, it introduces significant non-linearities in RGB data, complicating scientific analyses. We propose an innovative calibration method using LEGO® pieces as a reliable luminance reference, allowing for accurate gamma correction. Our methodology ensures consistent and precise measurements across varying lighting conditions, bridging the gap between traditional spectrophotometry and accessible image-based analysis. By comparing results from RGB cameras with UV-Vis spectroscopy, we demonstrate that corrected RGB data can reliably replicate spectrophotometric data in terms of contrast ratio and response time, making this approach viable for low-cost, portable diagnostics, as well as for diverse scientific applications. This work demonstrates the potential of RGB cameras in scientific research and proposes image analysis protocols for their use in electrochromic studies.