In this paper, we show how tone mapping techniques can be used to dynamically increase the image brightness, thus allowing the LCD backlight levels to be reduced. This saves significant power as the majority of the LCD's display power is consumed by its backlight. The Gamma function (or equivalent) can be efficiently implemented in smartphones with minimal resource cost. We describe how we overcame the Gamma function's non-linear nature by using adaptive thresholds to apply different Gamma values to images with differing brightness levels. These adaptive thresholds allow us to save significant amounts of power while preserving the image quality. We implemented our solution on a laptop and two Android smartphones. Finally, we present measured analytical results for two different games (Quake III and Planeshift), and user study results (using Quake III and 60 participants) that shows that we can save up to 68% of the display power without significantly affecting the perceived gameplay quality.

With the improved processing power, graphic quality and high-speed wireless connection in recent generations of mobile phone, it looks more attractive than ever to introduce networked games on these devices. While device features and application resource requirements are rapidly growing, the battery technologies are not growing at the same pace. Networked Mobile games are a class of application, which consume higher levels of energy, as they are naturally more computationally intensive and use hardware components including audio, display and network to their fullest capacities. Therefore, the main concern is the limitation of the battery power of such portable devices to support the potentially long-hour of game play.In this paper we present ARIVU, a power aware middleware that dynamically controls the energy consumption of wireless interface based on the game and system state while maintaining the user experience. ARIVU provides the relevant API for game developers to easily integrate the middleware. We measure power consumption of game play over different wireless interfaces including 3.5G (HSPA), 802.11g and ZigBee. The middleware is able to save up to 40% of the total energy consumed by the wireless interfaces (802.11g and ZigBee). In addition, we show the efficiency of ZigBee interface as potential low power interface for networked game applications.

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