python基于opencv实现分析每帧视频，从视频画面中提取出乒乓球的遮罩，然后再提取出乒乓球。

首先要利用VideoCapture读入视频信息。采用颜色追踪的方法来确定小球位置，查找遮罩图的轮廓，确定该轮廓的包围框，将包围框的中心作为乒乓球的位置，更新乒乓球位置

具体代码：

import cv2
import numpy as np



def empty(a):
    pass


def draw_direction(img, lx, ly, nx, ny):
    dx = nx - lx
    dy = ny - ly
    if abs(dx) < 4 and abs(dy) < 4:
        dx = 0
        dy = 0
    else:
        r = (dx**2 + dy**2)**0.5
        dx = int(dx/r*40)
        dy = int(dy/r*40)

    cv2.arrowedLine(img, (60, 100), (60+dx, 100+dy), (0, 255, 0), 2)#窗口设定



frameWidth = 640
frameHeight = 480
cap = cv2.VideoCapture("pingpangqiu.mp4")
cap.set(3, frameWidth)
cap.set(4, frameHeight)
cap.set(10, 80)        # 设置亮度
pulse_ms = 30


lower = np.array([4, 180, 156])     # 橙色乒乓球4<=h<=32
upper = np.array([32, 255, 255])

targetPos_x = 0
targetPos_y = 0
lastPos_x = 0
lastPos_y = 0

while True:
    _, img = cap.read()

    imgHsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)



    imgMask = cv2.inRange(imgHsv, lower, upper)     # 获取遮罩

    imgOutput = cv2.bitwise_and(img, img, mask=imgMask)
    contours, hierarchy = cv2.findContours(imgMask, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_NONE)   # 查找轮廓
    imgMask = cv2.cvtColor(imgMask, cv2.COLOR_GRAY2BGR)     # 转换后，后期才能够与原画面拼接，否则与原图维数不同

    orange_lower = np.array([11, 43, 46])
    orange_upper = np.array([25, 255, 255])  # 颜色色域
    img_hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)  # 转换为hsv
    mask = cv2.inRange(img_hsv, orange_lower, orange_upper)  # mask 启动
    mask = cv2.erode(mask, None, iterations=2)
    mask = cv2.GaussianBlur(mask, (3, 3), 0)
    # erode 和 GaussianBlur 是用来使得图片或视频更加模糊的 这样可以突出色彩，色彩追踪也会更加精准


    imgStack = np.hstack([img, imgOutput])
    cv2.imshow('Horizontal Stacking', imgStack)     # 显示
    cv2.imshow('mask', mask)
    if cv2.waitKey(pulse_ms) & 0xFF == ord('q'):          # 按下“q”退出
        print("Quit\n")
        break

cap.release()
cv2.destroyAllWindows()