汽车牌照识别系统

import cv2
import numpy as np

def locate_plate(image_path):
    image = cv2.imread(image_path)
    gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
    blurred = cv2.GaussianBlur(gray, (5, 5), 0)
    edged = cv2.Canny(blurred, 50, 150)
    
    contours, _ = cv2.findContours(edged.copy(), cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)
    contours = sorted(contours, key=cv2.contourArea, reverse=True)[:10]
    
    plate_contour = None
    for contour in contours:
        perimeter = cv2.arcLength(contour, True)
        approx = cv2.approxPolyDP(contour, 0.02 * perimeter, True)
        if len(approx) == 4:
            plate_contour = approx
            break
    
    if plate_contour is not None:
        x, y, w, h = cv2.boundingRect(plate_contour)
        cv2.rectangle(image, (x, y), (x + w, y + h), (0, 255, 0), 2)
        cv2.imshow("Plate", image)
        cv2.waitKey(0)
    else:
        print("No plate found")

locate_plate("path_to_image.jpg")