yolov5m-license-plate

Detects and localizes license plates in images using YOLOv5m architecture, which employs a single-stage convolutional neural network with multi-scale feature pyramid for efficient bounding box regression and confidence scoring. The model processes images through a backbone (CSPDarknet), neck (PANet), and head (detection layers) to output bounding box coordinates, confidence scores, and class predictions in a single forward pass without region proposal generation.

Processes multiple images sequentially or in parallel batches through the YOLOv5m detector, applying configurable confidence thresholds and non-maximum suppression (NMS) to filter low-confidence detections and remove overlapping bounding boxes. Outputs structured results per image with optional filtering by detection confidence, enabling downstream filtering of uncertain predictions before OCR or database storage.

Extracts detected license plate regions from source images by computing bounding box coordinates and cropping the original image to isolate the plate area. Supports padding/margin expansion around detected boxes for downstream OCR preprocessing, and can apply optional image normalization (resizing, contrast enhancement) to standardize plate regions for character recognition models.

Provides inference compatibility across multiple deep learning frameworks through model export and runtime abstraction. The YOLOv5m model can be loaded and executed via PyTorch (native), TensorFlow (converted weights), or ONNX Runtime (optimized for production), enabling deployment flexibility across different hardware and software stacks without retraining or architecture changes.

Reduces model size and inference latency through quantization techniques (INT8, FP16) and pruning, enabling deployment on resource-constrained devices (mobile, embedded, IoT). YOLOv5m can be quantized to ~10MB (from ~40MB) with minimal accuracy loss, and inference latency improves 2-4x on edge hardware (Jetson Nano, Raspberry Pi) through framework-specific optimizations (TensorRT, CoreML, OpenVINO).

Applies configurable confidence thresholds and non-maximum suppression (NMS) to filter low-confidence detections and remove overlapping bounding boxes. The model outputs raw predictions (bounding boxes, confidence scores) which are post-processed using NMS with IoU (Intersection over Union) threshold to eliminate duplicate detections and retain only high-confidence plates, enabling precision-recall tradeoff tuning.

Computes standard object detection metrics (mAP, precision, recall, F1-score) by comparing predicted bounding boxes against ground truth annotations using IoU-based matching. Supports evaluation on validation/test datasets with detailed per-class metrics, confusion matrices, and visualization of detection performance across confidence thresholds, enabling quantitative assessment of model accuracy on license plate detection tasks.

Enables fine-tuning the pre-trained YOLOv5m model on custom license plate datasets by leveraging transfer learning. The model's backbone and neck are pre-trained on general object detection; only the detection head is retrained on domain-specific plate data, reducing training time and data requirements compared to training from scratch. Supports data augmentation (mosaic, mixup, rotation) and hyperparameter tuning for improved convergence on custom datasets.

Generates annotated images with detected license plate bounding boxes, confidence scores, and class labels overlaid on the original image. Supports customizable visualization (box colors, label fonts, confidence thresholds for display) and batch visualization of detection results across multiple images, enabling visual inspection of model performance and debugging of detection failures.