DBS4video: dynamic luminance backlight scaling based on multi-histogram frame characterization for video streaming application

Almost every modern portable handheld device is equipped with a coloured LCD display. The backlight of the LCD accounts for a significant percentage of the total energy consumption. Substantial energy savings can be achieved by dynamically adapting backlight intensity levels on such low-power portable devices. In this paper, we present the DBS4video framework which allows dynamic scaling of the backlight with a negligible impact on QoS for video streaming applications. DBS4video exploits in a smart and efficient way the hardware image processing unit integrated in almost every new multimedia application processor to implement a hardware assisted image compensation. The proposed approach overcomes CPU-intensive techniques by saving system power without requiring either a dedicated display technology or hardware modification. We introduce also a new image processing kernel based on multiple histograms collection for a single frame. We provide a real implementation of the proposed framework on a Freescale application development board based on the i.MX31 processor. We carried out a full characterization of the overall system power consumption versus QoS.