Beacon: Post-Training Quantization with Integrated Grid Selection

Abstract: Quantization is a widely used compression technique for reducing the memory and computation costs of large pre-trained models. A key challenge in per-channel post-training quantization (PTQ) is selecting appropriate scaling factors to replace weight values with values from a scaled quantization grid. Existing methods typically fix the scale at the outset via heuristic tuning or grid search. In this note, we propose Beacon, a simple and effective algorithm that eliminates the need for such manual tuning. Beacon performs per-channel PTQ directly using a fixed non-scaled alphabet and automatically determines the optimal scaling factors by exploiting the geometry of symmetric scalar quantization. It supports both symmetric and asymmetric quantization with minimal modifications and does not rely on back-propagation or large calibration sets. Despite its simplicity and tuning-free nature, Beacon achieves competitive performance compared to state-of-the-art methods, making it a practical solution for efficient model deployment.