Quality Adapted Backlight Scaling (QABS) for Video Streaming to Mobile Handheld Devices
For a typical portable handheld device, the backlight accounts for a significant percentage of the total energy consumption (e.g., around 30% for a Compaq iPAQ 3650). Substantial energy savings can be achieved by dynamically adapting backlight intensity levels on such low-power portable devices. In this paper, we analyze the characteristics of video streaming services and propose an adaptive scheme called Quality Adapted Backlight Scaling (QABS), to achieve backlight energy savings for video playback applications on handheld devices. Specifically, we present a fast algorithm to optimize backlight dimming while keeping the degradation in image quality to a minimum so that the overall service quality is close to a specified threshold. Additionally, we propose two effective techniques to prevent frequent backlight switching, which negatively affects user perception of video. Our initial experimental results indicate that the energy used for backlight is significantly reduced, while the desired quality is satisfied. The proposed algorithms can be realized in real time.
Unable to display preview. Download preview PDF.
- 1.Pasricha, S., Luthra, M., Mohapatra, S., Dutt, N., Venkatasubramanian, N.: Dynamic Backlight Adaptation for Low Power Handheld Devices. To appear in IEEE Design and Test (IEEE D&T), Special Issue on Embedded Systems for Real Time Embedded Systems (September 2004)Google Scholar
- 2.Chang, N., Choi, I., Shim, H.: DLS: Dynamic Backlight Luminance Scaling of Liquid Crystal Display. IEEE Transaction on VLSI System 1 (August 2004)Google Scholar
- 3.Cheng, W.-C., Hou, Y., Pedram, M.: Power Minimization in a Backlit TFT-LCD Display by Concurrent Brightness and Contrast Scaling. In: Proceedings of the Design, Automation and Test in Europe (February 2004)Google Scholar
- 4.Zachary, J.L.: Introduction to Scientific Programming: Computational Problem Solving Using Maple and C. Telos Publishers (1996)Google Scholar