车牌检测的python代码

以下是基于OpenCV实现的车牌检测的Python代码：

import cv2
import numpy as np

# 读入图片
img = cv2.imread('car.jpg')

# 将图片转换为灰度图
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

# 进行高斯模糊
blur = cv2.GaussianBlur(gray, (5, 5), 0)

# 进行Canny边缘检测
edges = cv2.Canny(blur, 100, 200)

# 进行形态学操作
kernel = cv2.getStructuringElement(cv2.MORPH_RECT, (5, 5))
closed = cv2.morphologyEx(edges, cv2.MORPH_CLOSE, kernel)

# 寻找轮廓
contours, hierarchy = cv2.findContours(closed, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE)

# 遍历轮廓
for contour in contours:
    # 计算轮廓的面积和周长
    area = cv2.contourArea(contour)
    perimeter = cv2.arcLength(contour, True)

    # 进行面积和周长的筛选
    if area > 1000 and perimeter > 100:
        # 进行透视变换
        rect = cv2.minAreaRect(contour)
        box = cv2.boxPoints(rect)
        box = np.int0(box)
        cv2.drawContours(img, [box], 0, (0, 0, 255), 2)

# 显示结果
cv2.imshow('License Plate Detection', img)
cv2.waitKey(0)
cv2.destroyAllWindows()

需要注意的是，这段代码只是一个简单的车牌检测示例，实际应用中还需要对检测到的车牌进行字符识别等后续处理。