Python Opencv实践 - 矩形轮廓绘制(直边矩形，最小外接矩形)

import cv2 as cv
import numpy as np
import matplotlib.pyplot as pltimg = cv.imread("../SampleImages/stars.png")
plt.imshow(img[:,:,::-1])img_gray = cv.cvtColor(img, cv.COLOR_BGR2GRAY)
#通过cv.threshold转换为二值图
ret,thresh = cv.threshold(img_gray, 127, 255, 0)
plt.imshow(thresh, cmap=plt.cm.gray)#轮廓检测
contours,hierarchy = cv.findContours(thresh, 1, 2)
#绘制轮廓
img_contours_org = img.copy()
img_contours_org = cv.drawContours(img_contours_org, contours, -1, (0,255,0), 2)
plt.imshow(img_contours_org[:,:,::-1])img_rect_contour = img.copy()
for contour in contours:#1. 绘制直边界矩形#x,y,w,h = cv.boundingRect(contour)#contour: 轮廓信息#x,y,w,h: 矩形左上角(x,y)坐标，以及矩形的宽度和高度#参考资料：https://blog.csdn.net/hjxu2016/article/details/77833984x,y,w,h = cv.boundingRect(contour)img_rect_contour = cv.rectangle(img_rect_contour, (x,y), (x+w,y+h), (0,255,0), 2)#2. 绘制旋边界矩形结果#rect = cv.minAreaRect(contour)#contour：轮廓信息#rect: 最小外接矩阵的信息（中心（x,y）,（w,h）,旋转角度）#参考资料：https://blog.csdn.net/lanyuelvyun/article/details/76614872rect = cv.minAreaRect(contour)#使用boxPoints获得最小外接矩阵的4个顶点坐标box = cv.boxPoints(rect)#转换为int类型box = np.intp(box)#使用cv.polylines绘制外接矩形cv.polylines(img_rect_contour, [box], True, (0,0,255), 2)plt.imshow(img_rect_contour[:,:,::-1])