python-opencv 机器视觉 质心，形心 坐标 颜色分拣

#!/usr/bin/python
# -*- coding: utf-8 -*-
import cv2
import time
import numpy as np
from matplotlib import pyplot as plt
import cv2.cv as cv

capture = cv2.VideoCapture(0)
print capture.isOpened()

while True:
    ret, image = capture.read()
    hsv = cv2.cvtColor(image, cv2.COLOR_BGR2HSV)    # 转HSV空间
    # define range of blue color in HSV #定义取值的颜色空间
    lower_blue = np.array([10, 50, 50])
    upper_blue = np.array([40, 255, 255])
    # Threshold the HSV image to get only blue colors
    mask = cv2.inRange(hsv, lower_blue, upper_blue)
    # Bitwise-AND mask and original image
    res = cv2.bitwise_and(image, image, mask=mask)

    # 构造5×5的结构元素，分别为十字形、菱形、方形和X型
    cross = cv2.getStructuringElement(cv2.MORPH_CROSS,(5, 5))       # 十字形
    # 菱形结构元素的定义稍麻烦一些
    diamond = cv2.getStructuringElement(cv2.MORPH_RECT,(5, 5))      # 菱形
    diamond[0, 0] = 0
    diamond[0, 1] = 0
    diamond[1, 0] = 0
    diamond[4, 4] = 0