OpenCv学习3——色彩空间

什么是色彩空间

https://zhuanlan.zhihu.com/p/28741691（参考知乎专栏）

常见的色彩空间

• RGB
• HSV
• HIS
• YCrCb
• YUV

代码层面的知识点

色彩空间相互转换（RGB HSV YUV常用）

def color_space_demo(image):
    gray = cv.cvtColor(image, cv.COLOR_BGR2GRAY)
    cv.imshow("gray", gray)
    hsv = cv.cvtColor(image, cv.COLOR_BGR2HSV)
    cv.imshow("hsv", hsv)
    yuv = cv.cvtColor(image, cv.COLOR_BGR2YUV)
    cv.imshow("yuv", yuv)
    Ycrcb = cv.cvtColor(image, cv.COLOR_BGR2YCrCb)
    cv.imshow("Ycrcb", Ycrcb)

 

学会使用inRange

应用：提取视频中特定颜色的物品（追踪有颜色的对象）

首先提取一段视频

def extract_object_demo():
    capture = cv.VideoCapture("H:codingpython_opencv_tutorial_codespracticelisa.mp4")
    while(True):
        ret, frame = capture.read()
        if ret == False:
            break
        cv.imshow("video", frame)
     c = cv.waitKey(50)
        if c == 27:
            break

hsv二值化（找黄颜色）

def extract_object_demo():
    capture = cv.VideoCapture("H:codingpython_opencv_tutorial_codespracticelisa.mp4")
    while(True):
        ret, frame = capture.read()
        if ret == False:
            break
        hsv = cv.cvtColor(frame, cv.COLOR_BGR2HSV)
        lower_hsv = np.array([26, 43, 46])
        higer_hsv = np.array([34, 255, 255])
        mask = cv.inRange(hsv, lower_hsv, higer_hsv)#得到二值图像
        cv.imshow("video", frame)
        cv.imshow("mask", mask)
        c = cv.waitKey(50)
        if c == 27:
            break

通道的分离与合并

b, g, r = cv.split(src)#三通道分离
cv.imshow("blue", b)
cv.imshow("green", g)
cv.imshow("red", r)

src[:,:,2] = 0
src = cv.merge([b, g, r])#三通道合并
cv.imshow("changed image", src)

 本章内容完整代码

import cv2 as cv
import numpy as np

def extract_object_demo():
    capture = cv.VideoCapture("H:codingpython_opencv_tutorial_codespracticelisa.mp4")
    while(True):
        ret, frame = capture.read()
        if ret == False:
            break
        hsv = cv.cvtColor(frame, cv.COLOR_BGR2HSV)
        lower_hsv = np.array([26, 43, 46])
        higer_hsv = np.array([34, 255, 255])
        mask = cv.inRange(hsv, lower_hsv, higer_hsv)#得到二值图像
        cv.imshow("video", frame)
        cv.imshow("mask", mask)
        c = cv.waitKey(50)
        if c == 27:
            break

def color_space_demo(image):
    gray = cv.cvtColor(image, cv.COLOR_BGR2GRAY)
    cv.imshow("gray", gray)
    hsv = cv.cvtColor(image, cv.COLOR_BGR2HSV)
    cv.imshow("hsv", hsv)
    yuv = cv.cvtColor(image, cv.COLOR_BGR2YUV)
    cv.imshow("yuv", yuv)
    Ycrcb = cv.cvtColor(image, cv.COLOR_BGR2YCrCb)
    cv.imshow("Ycrcb", Ycrcb)

print("---------hello python---------")
src = cv.imread("H:codingpython_opencv_tutorial_codespracticekrystal.jpg")
cv.namedWindow("input image", cv.WINDOW_AUTOSIZE)
cv.imshow("input image", src)

b, g, r = cv.split(src)#三通道分离
cv.imshow("blue", b)
cv.imshow("green", g)
cv.imshow("red", r)

src[:,:,2] = 0
src = cv.merge([b, g, r])#三通道合并
cv.imshow("changed image", src)
#print(type(src))
#color_space_demo(src)
#extract_object_demo()
cv.waitKey(0)
cv.destroyAllWindows()