Using Video Technology for Reducing TV Energy Choong Geun Lee, Vasily G. Moshnyaga and Koji Hashimoto Department of Electronics Engineering and Computer Science, Fukuoka University 8-19-1 Nanakuma, Jonan-ku, Fukuoka, 814-0144 Japan Abstract— In this paper we present a new approach to lower energy consumption of television set. Unlike existing methods, which “sense” a TV viewer through motion sensor or remote controller, our approach “monitors” the viewer through a video camera. The proposed method keeps TV screen active only if there is someone looking at the screen. When no viewer is present in front of the camera, the TV screen is dimmed to save power while the TV audio system is kept ON. Experiments show that such energy management can reduce the TV power consumption significantly especially when TV is left ON unwatched. I. INTRODUCTION A. Motivation of this work Despite of wide acceptance of “green energy” regulations, TVs have become more energy consuming. Recently emerged plasma televisions, which are 50% bigger than their cathode-ray tube equivalents, consume about four times more energy [1]. A 50-inch flat-screen plasma HDTV now burns over 500Watts [2] of power consuming same energy as dishwasher or in-room air-conditioner. However the problem does not relate only to plasma TV. The LCD TV sets also consume a lot. A typical 42” LCD TV takes 169-250Watts of power per each hour [2]. According to Nielsen Media Research Inc. [3] over 99% of all households in US have TV sets, with 2.24 TVs per household in average. The number of hours TV is watched annually by Americans is 250 billion! As result, reducing TVs energy has become a very important problem. B. Related research A number of methods have been proposed to save TV energy. Dimming the screen brightness is one of the most effective power saving techniques proposed for TV. A common approach is to scale down or dim the backlight luminance. This approach is based on observation that transmissive and transflective color TFT LCD panels [4] do not illuminate itself but filter a backlight, the primary source of display energy dissipation. Because simply dimming the backlight degrades the screen visibility, Choi, et al [5] proposed to maintain brightness or contrast of the LCD panel when the backlight is dimmed down. To reduce the average energy demands of the backlight, Gatti, et al [6] suggested the backlight auto regulation scheme. Cheng and Pedram [7] showed that a concurrent brightness and contrast scaling (CBCS) technique further enhances image fidelity with a dim backlight, and thus saves an extra power. Chang, et al [8] introduced a dynamic luminance scaling or DLS technique that dimmed the backlight while allowing more light to pass through the screen panel to compensate for the loss of brightness in the original image. Shim, et al [9] combined the DLS technique with dynamic contrast enhancement and applied it for transflective TFT LCD panels. Pasricha, et al [10] presented an adaptive middleware-based technique to optimize backlight power when playing streaming video. A modification of the LCD panel to permit zoned backlighting is discussed in [11]. There are also a variety of schemes for automated adjustment of brightness in high dynamic range panoramic images, e.g. [12-13]. These schemes dynamically brighten or darken image regions depending on the scene content and average local luminance. The view-port center (the center of area with dimensions (width/2*height/2) is constantly monitored and the average pixel luminance of the view-port is calculated. This value is then compared with a preset optimum value and brightness is adjusted accordingly. Despite differences, the proposed brightness and/or contrast adjustment techniques have one feature in common. Namely, they work independently of the viewer presence. In modern TVs, users can set the brightness by selecting one of three operation modes: the “standard mode” delivers the highest level of brightness; the “saving mode” refers to the dimmed screen and “no brightness mode” reflects the dark screen. The brightness level in the saving mode can also be changed. Unless the user changes the mode, the TV maintains same brightness independently of whether the user watches the TV or not. Similarly to computer users, majority of TV viewers do not change brightness for energy savings, fearing that it affects picture quality. Besides, users usually watch TV while doing other activities: reading books, working on PC, preparing food, chatting with friends, etc. According to statistics, a TV is ON for almost 5 hours in an average US home a day [3]. In other words, a TV only The work was sponsored by The Ministry of Education, Culture, Sports, Science and Technology of Japan, Grant-in-Aid for Scientific Research (C) No.19500049