Visual quality analysis for dynamic backlight scaling in LCD systems

—With the trend toward high-quality large form factor displays on high-end handhelds, LCD backlight accounts for a significant and increasing percentage of the total energy budget. Substantial energy savings can be achieved by dynamically adapting backlight intensity levels while compensating for the ensuing visual quality degradation with image pixel transformations. Several compensation techniques have been recently developed to this purpose, but none of them has been fully characterized in terms of quality losses considering jointly the non-idealities present in a real embedded video chain and the peculiar characteristics of the human visual system (HVS). We have developed a quality analysis framework based on an accurate embedded visualization system model and HVS-aware metrics. We use it to assess the visual quality performance of existing dynamic backlight scaling (DBS) solutions. Experimental results show that none of the DBS techniques available today is fully capable of keeping quality loss under control, and that there is significant room for improvement in this direction.