[rectangle]绘制边框
定义
def rectangle(img, pt1, pt2, color, thickness=None, lineType=None, shift=None):
img：图像pt1：左上角坐标点pt2：右下角坐标点color：颜色thickness：线条粗细程度lineType：线条类型，参考LineTypes
Note：在输入图像上进行边框绘制
示例
import cv2
import numpy as np
if __name__ == '__main__':
# 创建空白3通道图像
img = np.ones((500, 500, 3)) * 255
cv2.rectangle(img, (20, 20), (120, 120), (0, 0, 255), thickness=1)
cv2.rectangle(img, (50, 100), (380, 450), (0, 255, 0), thickness=2)
cv2.imshow('img', img)
cv2.waitKey(0)
