Organic light-emitting diode (OLED) technology is considered as a promising alternative to mobile displays. This paper explores how to reduce the OLED power consumption by exploiting visual attention. First, we model the problem of OLED image scaling optimization, with the objective of minimizing the power required to display an image without adversely impacting the user's visual experience. Then, we propose an algorithm to solve the fundamental problem, and prove its optimality even without the accurate power model. Finally, based on the algorithm, we consider implementation issues and realize two application scenarios on a commercial OLED mobile tablet. The results of experiments conducted on the tablet with real images demonstrate that the proposed methodology can achieve significant power savings while retaining the visual quality.