PR #58: Number Plate Detection using OpenCV

Add number plate detection using OpenCV (clean submission)
Merge pull request #58 from iamdevdhanush/number_plate_detection

Author: iamwatchdogs

Number-Plate-Detection/Numberplatedetection.py

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+import cv2
+import os
+import time
+
+cascade_path = cv2.data.haarcascades + "haarcascade_russian_plate_number.xml"
+plate_cascade = cv2.CascadeClassifier(cascade_path)
+
+if plate_cascade.empty():
+    raise IOError("Error loading Haar cascade")
+
+# Output directory
+os.makedirs("plates", exist_ok=True)
+
+cap = cv2.VideoCapture(0)
+if not cap.isOpened():
+    raise IOError("Cannot open webcam")
+
+plate_count = 0
+last_save_time = 0
+save_delay = 0.5 
+
+while True:
+    ret, frame = cap.read()
+    if not ret:
+        break
+
+    frame = cv2.resize(frame, (960, 540))
+    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
+    gray = cv2.equalizeHist(gray)
+    gray = cv2.bilateralFilter(gray, 11, 17, 17)
+
+    roi = gray[270:540, :]
+    plates = plate_cascade.detectMultiScale(
+        roi,
+        scaleFactor=1.05,
+        minNeighbors=7,
+        minSize=(60, 20)
+    )
+
+    current_time = time.time()
+
+    for (x, y, w, h) in plates:
+        y += 270
+        aspect_ratio = w / h
+
+        if 2 < aspect_ratio < 5:
+            cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 255, 0), 2)
+
+            if current_time - last_save_time > save_delay:
+                plate_count += 1
+                plate_img = frame[y:y+h, x:x+w]
+                cv2.imwrite(f"plates/plate_{plate_count}.jpg", plate_img)
+                last_save_time = current_time
+
+    cv2.imshow("Number Plate Detection", frame)
+
+    if cv2.waitKey(1) & 0xFF == ord("q"):
+        break
+
+cap.release()
+cv2.destroyAllWindows()

Number-Plate-Detection/README.md

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+# Number Plate Detection 🚘🔍
+
+This project is a simple **Number Plate Detection** system built using **Python** and **OpenCV**.  
+It uses classical image processing techniques and OpenCV’s **built-in Haar Cascade classifier** to detect vehicle number plates in real time using a webcam.
+
+---
+
+## 📸 Demo
+
+![Demo Screenshot](https://github.com/user-attachments/assets/fd6d233e-a948-4015-aab3-50ec09ac9f75)
+
+---
+
+## 🧠 Features
+
+- Real-time number plate detection using webcam
+- Uses OpenCV’s built-in Haar Cascade classifier
+- Draws bounding boxes around detected number plates
+- Lightweight and beginner-friendly
+- Can be extended for OCR (text extraction)
+
+---
+
+## 🛠️ Technologies Used
+
+- Python 3.x
+- OpenCV
+
+---
+
+
+## 📁 Project Structure
+
+```
+Number-Plate-Detection/
+│
+├── Numberplatedetection.py   # Main script
+└── README.md                 # Project documentation
+```
+