A Real-time Energy-Efficient Superpixel Hardware Accelerator for Mobile Computer Vision Applications

Superpixel generation is a common preprocessing step in vision processing aimed at dividing an image into non-overlapping regions. Simple Linear Iterative Clustering (SLIC) is a commonly used superpixel algorithm that offers a good balance between performance and accuracy. However, the algorithm’s high computational and memory bandwidth requirements result in performance and energy efficiency that do not meet the requirements of realtime embedded applications. In this work, we explore the design of an energy-efficient superpixel accelerator for real-time computer vision applications. We propose a novel algorithm, Subsampled SLIC (S-SLIC), that uses pixel subsampling to reduce the memory bandwidth by 1.8x. We integrate S-SLIC into an energy-efficient superpixel accelerator and perform an in-depth design space exploration to optimize the design. We completed a detailed design in a 16nm FinFET technology using commercially-available EDA tools for high-level synthesis to map the design automatically from a C-based representation to a gate-level implementation. The proposed S-SLIC accelerator achieves real-time performance (30 frames per second) with 250x better energy efficiency than an optimized SLIC software implementation running on a mobile GPU.