Add production ALPR models (YOLO detector + CRNN reader + CNN fallback) and model card
Browse files- README.md +117 -0
- ocr_cnn.labels.json +30 -0
- ocr_cnn.onnx +3 -0
- ocr_crnn.labels.json +1 -0
- ocr_crnn.onnx +3 -0
- plate_yolo.onnx +3 -0
README.md
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---
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license: mit
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language:
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- fa
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library_name: onnxruntime
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pipeline_tag: image-to-text
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tags:
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- alpr
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- license-plate-recognition
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- ocr
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- persian
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- farsi
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- iranian-license-plate
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- crnn
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- ctc
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- yolo
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- onnx
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- object-detection
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---
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# ocr-persian — Iranian License-Plate Recognition Models
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Production ONNX models for detecting and reading **Iranian vehicle license
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plates**, powering the [**Platrix**](https://github.com/AliAkrami1375/Platrix)
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real-time, self-hosted plate-surveillance system.
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The pipeline is **two-stage**: a YOLO **detector** locates the plate in the
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frame, then a segmentation-free **CRNN + CTC reader** reads the whole plate at
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once and returns the standard Iranian layout `DD L DDD DD`
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(two digits · letter · three digits · two-digit region), e.g. `۸۱ و ۶۳۸ ۱۳`.
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All models run with **ONNX Runtime** — no PyTorch or TensorFlow needed at
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inference time.
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---
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## Files
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| File | Role | Input | Output |
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|------|------|-------|--------|
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| `plate_yolo.onnx` | **Plate detector** (YOLOv8) | `1×3×H×W` RGB, letterboxed, `/255` | `1×5×N` → `cx,cy,w,h,conf` |
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| `ocr_crnn.onnx` | **Whole-plate reader** (CRNN+CTC) — *recommended* | `1×1×32×128` grayscale, `/255` | `1×T×(C+1)` logits (CTC, blank = last) |
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| `ocr_crnn.labels.json` | Class list for the CRNN (index → character) | — | 32 classes |
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| `ocr_cnn.onnx` | Per-character classifier (lightweight fallback) | `1×1×32×32` grayscale | class logits |
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| `ocr_cnn.labels.json` | Class list for the per-char classifier | — | — |
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**Character set (32 classes):** digits `0–9` and the Persian plate letters
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`ا ب ت ث ج ح د ز س ش ص ط ع ق ل م ن ه و پ ژ ی`.
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---
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## Why a segmentation-free reader?
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Splitting a plate into individual characters is fragile on real photos
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(shadows, motion blur, tilt, dirt). The CRNN reads the **entire plate in one
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pass** with a CTC head, which is far more robust. It is trained on **real
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Iranian plate-character shapes**, so look-alike glyphs (e.g. the digit `۴` vs
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`۶`) are read correctly.
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A key detail: the **same image-enhancement** (upscale → denoise → CLAHE
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contrast → unsharp) is applied both during training and at serving time, so
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there is no train/serve mismatch — the enhancement genuinely helps accuracy
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instead of shifting the input distribution.
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---
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## Quick usage
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```bash
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pip install onnxruntime opencv-python-headless numpy
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huggingface-cli download Dibachain/ocr-persian \
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plate_yolo.onnx ocr_crnn.onnx ocr_crnn.labels.json --local-dir models/
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```
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```python
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import json, cv2, numpy as np, onnxruntime as ort
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# --- Reader (CRNN + CTC) ---
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labels = json.load(open("models/ocr_crnn.labels.json", encoding="utf-8"))
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blank = len(labels) # CTC blank is the last index
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crnn = ort.InferenceSession("models/ocr_crnn.onnx", providers=["CPUExecutionProvider"])
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def read_plate(plate_bgr):
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g = cv2.cvtColor(plate_bgr, cv2.COLOR_BGR2GRAY)
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g = cv2.resize(g, (128, 32)).astype(np.float32) / 255.0 # 1x1x32x128
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logits = crnn.run(None, {"input": g[None, None]})[0][0] # T x (C+1)
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ids, out, prev = logits.argmax(1), [], -1
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for i in ids: # greedy CTC decode
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if i != blank and i != prev:
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out.append(labels[i])
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prev = i
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return "".join(out)
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```
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Run `plate_yolo.onnx` first to crop the plate from a full frame (standard
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YOLOv8 letterbox pre-process + confidence/NMS post-process), then pass the crop
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to `read_plate`. The full, batteries-included pipeline — detection, enhancement,
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grammar-constrained decoding, multi-camera streaming, watchlists and a web
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dashboard — lives in the [Platrix repository](https://github.com/AliAkrami1375/Platrix).
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---
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## Intended use & limitations
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- **Intended for** lawful applications such as parking management, access
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control, gate automation and traffic analytics.
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- **Optimised for** standard private Iranian plates. Very low-resolution,
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heavily occluded, or non-standard plates may reduce accuracy.
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- You are responsible for complying with the privacy and surveillance laws that
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apply to your deployment.
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---
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## Links
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- **Project & full pipeline:** https://github.com/AliAkrami1375/Platrix
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- **License:** MIT
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ocr_cnn.labels.json
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[
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"0",
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"1",
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"2",
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"3",
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"4",
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"5",
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"6",
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"7",
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"8",
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"9",
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"ا",
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"ب",
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"ت",
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"ج",
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"د",
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"س",
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"ص",
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"ط",
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"ع",
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"ق",
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"ل",
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"م",
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"ن",
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"ه",
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"و",
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"پ",
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"ژ",
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"ی"
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]
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ocr_cnn.onnx
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version https://git-lfs.github.com/spec/v1
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oid sha256:7d573c51cc855a8e080f1f88597477f4fb5a2b9cafa1bb125bd6038e441f5bca
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size 2226402
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ocr_crnn.labels.json
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["0", "1", "2", "3", "4", "5", "6", "7", "8", "9", "ا", "ب", "ت", "ث", "ج", "ح", "د", "ز", "س", "ش", "ص", "ط", "ع", "ق", "ل", "م", "ن", "ه", "و", "پ", "ژ", "ی"]
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ocr_crnn.onnx
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version https://git-lfs.github.com/spec/v1
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oid sha256:45f8c45f29eb1ee91f6274cb8d9c328da1a2050ea7d8596bae61f4a6b9f9fb1e
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size 10452525
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plate_yolo.onnx
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version https://git-lfs.github.com/spec/v1
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oid sha256:a54e475c402e6036bb5c70f1a6ff75179e76098a5c8039bb5d148c0b6421f5c6
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size 12608775
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