A Camera-Based Energy Management of Computer Displays and TV Sets

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With increase in image quality and screen sizes, the energy consumption of computer displays and television sets has significantly grown. In a typical personal computer or PC, display accounts for 30%~50% of the total PC energy consumption [Mahesri 2005, Robertson 2002]. For instance, typical 19 inch LCD monitor, such as Sony SDM-S93 (1280x1024 pixels), burns in active mode 50W or almost 38% of the total desktop system power (130W). With large popularity of video and gaming applications, LCD makers are being called on to cut power consumption while providing better images. Rapid utilization of multiple displays -each consuming tens of watts -throughout homes, offices and buildings increases cost and environmental impact of energy consumption significantly. Although most PC displays support power management, new robust methods are needed for evolving display usage scenarios. For TV sets, the quest for efficient display energy management is more severe, because modern TVs have much bigger screens than computer displays and therefore consume more power. Although the LCD TVs are more efficient than their cathode-ray tubes (or CRT) TVs, recently emerged plasma television sets are twice as bigger and about four times more energy than their cathode-ray tube equivalents [Coughlan, 2006]. A 50-inch flat-screen plasma HDTV now burns over 500Watts of power [Plasma TV, 2006]; consuming almost the same amount of energy as dishwasher or in-room air-conditioner. The problem however does not relate only to plasma television sets. The LCD TV sets also consume a lot. A typical 42” LCD TV takes 169-250Watts of power per each hour [TV Power Consumption, 2008]. According to Nielsen Media Research Inc. [Nielsen 2009] over 99% of all households in US have TV sets, with 2.24 TVs per household in average. Since TV is ON for almost 5 hours in an average US home a day [Television & Health], it has become one of the largest energy consumers. Due to emerging problems of global warming and fossil fuel shortage, reducing TV energy is very important. Up to the date, reducing energy consumption of LCD displays has been tackled mainly through system and circuit optimizations, which either ignore the user, assuming fixed and stable demands on system operation or rely on very simplified policies, which eventually lead to large energy losses. Generally, there are two sources of energy losses in a device: intrinsic losses and the user-related losses. The intrinsic energy losses are caused by the engineering design, technology and materials used in construction of the device. For example, a plasma TV intrinsically dissipates more energy than a LCD TV, etc. The user-