OpenCV实例：方形检测

OpenCV实例：方形检测

本篇文章将为大家介绍如何使用OpenCV库进行方形检测的实现。通过该实例，我们可以轻松地检测图片或视频中的方形物体。

实现代码如下：

import cv2
import numpy as np
 
# 加载测试图片
img = cv2.imread('test.png')
 
# 灰度化处理
gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
 
# 边缘检测
edges = cv2.Canny(gray, 50, 150, apertureSize = 3)
cv2.imshow('edges', edges)
 
# 轮廓检测
contours, hierarchy = cv2.findContours(edges,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)
 
# 寻找方形轮廓
squares = []
for i in range(len(contours)):
    cnt = contours[i]
    area = cv2.contourArea(cnt)
    if area > 500 and area < 5000:
        perimeter = cv2.arcLength(cnt,True)
        approx = cv2.approxPolyDP(cnt,0.02*perimeter,True)
        if len(approx) == 4 and cv2.isContourConvex(approx):
            squares.append(approx)
 
# 绘制方形轮廓
cv2.drawContours(img