A 135-frames/s 1080p 87.5-mW Binary-Descriptor-Based Image Feature Extraction Accelerator

Binary image descriptors, which derive image feature description from the local image patches directly, are widely adopted in the mobile and embedded applications due to lower computational complexity and memory requirement. With the aim of improving the computation efficiency without degrading recognition performance, a lightweight binary robust descriptor is proposed based on the analysis of the state-of-the-art binary descriptors in this paper. A directional edge detection and optimized keypoint score function are developed to refine the keypoints. In addition, rotation invariance is achieved by executing circular symmetric-based descriptor generation and a coarse-grained orientation calculation method concurrently. The experimental results demonstrate that the proposed keypoint detector and binary descriptor achieve more than two times speedup and at least 23.6% improvement in processing speed with comparable performance, respectively. Furthermore, a very large scale integration architecture is also designed based on in-depth exploration of bit-level and task-level parallelism. Based on the postlayout simulation in a TSMC 65-nm CMOS process, the accelerator can achieve 135 frames/s on 1080p image while only consuming 87.5 mW at a 200-MHz operating frequency.