# 打开样图
img = cv.imread('dm2.png',0)
# 定义滚动条事件为打印当前的值
def nothing(x):
    minval = cv.getTrackbarPos('minval','image')
    maxval = cv.getTrackbarPos('maxval','image')
    print(f"当前阈值 min:{minval} max:{maxval}")
# 创建可改变大小的窗口
cv.namedWindow('image',cv.WINDOW_NORMAL)
# 定义min和max滚动条，绑定到窗口image
cv.createTrackbar('minval','image',0,255,nothing)
cv.createTrackbar('maxval','image',0,255,nothing)
# 初始化min和max值
minval = 100
maxval = 200
while(1):
    # 按esc退出
    k = cv.waitKey(1) & 0xFF
    if k == 27:
        break
    # 获取滚动条变化后的min和max值
    minval = cv.getTrackbarPos('minval','image')
    maxval = cv.getTrackbarPos('maxval','image')
    # 检测边缘后的图像
    edges = cv.Canny(img,minval,maxval)
    # 展示
    cv.imshow('image',edges)
# 自动销毁所有窗口
cv.destroyAllWindows()

image