Proper Body Landmark Subset Enables More Accurate and 5X Faster Recognition of Isolated Signs in LIBRAS
Lightweight keypoint detection for Brazilian Sign Language (LIBRAS) isolated-word recognition faces a fundamental trade-off between recognition accuracy and inference speed. Method: This paper proposes an efficient recognition framework based on optimized keypoint subset selection and missing-keypoint compensation. It employs MediaPipe for body keypoint extraction, introduces a discriminability-driven strategy to identify the minimal effective keypoint subset for sign motion representation, and applies spline interpolation to recover keypoints lost due to occlusion or detection failure. Contribution/Results: The method preserves skeletal motion fidelity while significantly reducing computational redundancy. Experiments demonstrate that, compared to state-of-the-art approaches, our method achieves a 1.2% absolute accuracy gain, a 5.3× speedup in inference latency, and a 68% reduction in model parameters—enabling scalable, robust sign language recognition under resource-constrained conditions.