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Real-time stereo vision is attractive in many applications like robot navigation and 3-D scene reconstruction. Data parallel platforms, e.g., graphics processing unit (GPU), are often used for real-time stereo, because most stereo algorithms involve a large portion of data parallel computations. In this paper, we propose a stereo system on GPU which pushes the Pareto-efficiency frontline in the accuracy and speed tradeoff space. Our system is based on a hardware-aware algorithm design approach. The system consists of new algorithms and code optimization techniques. We emphasize on keeping the highly data parallel structure in the algorithm design process such that the algorithms can be effectively mapped to massively data parallel platforms. We propose two stereo algorithms: namely, exponential step size adaptive weight (ESAW), and exponential step size message propagation (ESMP). ESAW reduces computational complexity without sacrificing disparity accuracy. ESMP is an extension of ESAW, which incorporates the smoothness term to better model non-frontal planes. ESMP offers additional choice in the accuracy and speed tradeoff space. We adopt code optimization methodologies from the performance tuning community, and apply them to this specific application. Such an approach gives higher performance than optimizing the code in an “ad hoc” manner, and helps understanding the code efficiency. Experiment results demonstrate a speedup factor of 2.7-8.5 over state-of-the-art stereo systems at comparable disparity accuracy.