Exploring eye adaptation in head-mounted display for energy efficient smartphone virtual reality

Smartphone virtual reality (VR) can offer immersive experience while being affordable and easy to use. To enhance the VR experience under limited smartphone computation and battery resources, solutions have been proposed for efficient rendering and content delivery. However, efforts towards optimizing the distinct headmounted display (HMD) are unfortunately limited. This paper unveils the opportunity of optimizing smartphone VR by leveraging human vision in HMD. In particular, we shift the default fixed full brightness in VR video/game Apps to a dark adaptation based dynamically scaled brightness. By exploiting the time-varying sensitivity of human eyes in dark HMD, we can reduce VR display energy while maintaining brightness perception. The proposed system, Strix, is empowered by a dark adaptation model trained from classic experimental data, a varying trend of perceptual full brightness derived from the dark adaptation model, and a smooth brightness transition scheme balancing energy and experience. Experimental results show that Strix can achieve 25% system energy reduction without negatively impacting brightness perception.