Nooree Na, a Ph.D. candidate of CED Lab made a presentation entitled “Dynamics of backlight luminance for using smartphone in dark environment” on the IS&T/SPIE Electronic Imaging (EI 2014) conference in CA: Burlingame, USA. This study proposes a dynamic backlight luminance, which gradually changes as time passes for comfortable use of a smartphone display in a dark environment. Jiho Jang, a master candidate of CED Lab contributed to the experiment and a co-author of the conference paper.

Abstract

This study developed dynamic backlight luminance, which gradually changes as time passes for comfortable use of a smartphone display in a dark environment. The study was carried out in two stages. In the first stage, a user test was conducted to identify the optimal luminance by assessing the facial squint level, subjective glare evaluation, eye blink frequency and users’ subjective preferences. Based on the results of the user test, the dynamics of backlight luminance was designed. It has two levels of luminance: the optimal level for initial viewing to avoid sudden glare or fatigue to users’ eyes, and the optimal level for constant viewing, which is comfortable, but also bright enough for constant reading of the displayed material. The luminance for initial viewing starts from 10 cd/m², and it gradually increases to 40 cd/m² for users’ visual comfort at constant viewing for 20 seconds; In the second stage, a validation test on dynamics of backlight luminance was conducted to verify the effectiveness of the developed dynamics. It involving users’ subjective preferences, eye blink frequency, and brainwave analysis using the electroencephalogram (EEG) to confirm that the proposed dynamic backlighting enhances users’ visual comfort and visual cognition, particularly for using smartphones in a dark environment.