opencv 颜色检测

参考：
https://stackoverflow.com/questions/20912948/color-detection-using-opencv-python

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1、检测蓝色

import cv2
import numpy as np

cap = cv2.VideoCapture("vtest.avi")

while(1):

    # Take each frame
    _, frame = cap.read()

    # Convert BGR to HSV
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    # define range of blue color in HSV
    lower_blue = np.array([110,50,50],np.uint8)
    upper_blue = np.array([130,255,255],np.uint8)

    # 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(frame,frame, mask= mask)

    cv2.imshow('frame',frame)
    cv2.imshow('mask',mask)
    cv2.imshow('res',res)
    k = cv2.waitKey(5) & 0xFF
    if k == 27:
        break

cv2.destroyAllWindows()

2、检测红色

import cv2
import numpy as np

cap = cv2.VideoCapture("vtest.avi")

while(1):

    # Take each frame
    _, frame = cap.read()

    # Convert BGR to HSV
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

    # define range of blue color in HSV
    lower_red = np.array([170, 70, 50], np.uint8)
    upper_red = np.array([180, 255, 255], np.uint8)
    # lower_red=cv2.cvtColor(np.array([[lower_red]]),cv2.COLOR_HSV2BGR)
    # upper_red = cv2.cvtColor(np.array([[upper_red]]), cv2.COLOR_HSV2BGR)

    # Threshold the HSV image to get only red colors
    mask = cv2.inRange(hsv, lower_red, upper_red)

    # Bitwise-AND mask and original image
    res = cv2.bitwise_and(frame,frame, mask= mask)

    cv2.imshow('frame',frame)
    cv2.imshow('mask',mask)
    cv2.imshow('res',res)
    k = cv2.waitKey(5) & 0xFF
    if k == 27:
        break

cv2.destroyAllWindows()