python cv2画点

要使用Python的cv2库在图像上画点，可以按照以下步骤进行操作：

1. 导入cv2模块和numpy模块：
import cv2
import numpy as np

2. 创建一个空白图像：
image = np.zeros((256, 256, 3), np.uint8)

3. 定义一个回调函数onmouse_pick_points，用于处理鼠标事件，在该函数中绘制点和输出坐标：
def onmouse_pick_points(event, x, y, flags, param):
if event == cv2.EVENT_LBUTTONDOWN:
print('x = %d, y = %d' % (x, y))
cv2.drawMarker(param, (x, y), (0, 255, 0))

4. 创建一个窗口并设置鼠标回调函数：
WIN_NAME = 'pick_points'
cv2.namedWindow(WIN_NAME, 0)
cv2.setMouseCallback(WIN_NAME, onmouse_pick_points, image)

5. 进入主循环，显示图像并等待键盘输入，按下ESC键退出：
while True:
cv2.imshow(WIN_NAME, image)
key = cv2.waitKey(30)
if key == 27: # ESC
break

6. 关闭窗口：
cv2.destroyAllWindows()

这样就可以通过鼠标点击，在图像上绘制点，并输出点的坐标。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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