一、简介
opencv有超150种颜色空间转换,在这里我们主要介绍2种经常用到的颜色空间转换(RGB->GRAY, RGB->HSV)。
HVS色相取值范围[0, 179],亮度取值范围[0, 255],饱和度取值范围[0, 255],不同的软件取值范围可能不一样。
二、查询
查询opencv支持哪些颜色转换类型,可以使用以下方法。
import cv2 as cvflags = [i for i in dir(cv) if i.startswith('COLOR_')]print( flags )
三、RGB转GRAY
以下为转换代码:
import numpy as npimport cv2 as cvimg = cv.imread('./img/frame.jpg')gray = cv.cvtColor(img, cv.COLOR_RGB2GRAY)cv.imshow('img', img)cv.imshow('gray', gray)cv.waitKey(0)cv.destroyAllWindows()
四、RGB转HSV
以下为通过RGB转HSV实现简单目标追踪(通过颜色来追踪)代码示例:
import cv2 as cvimport numpy as npcap = cv.VideoCapture(0)while(1):# Take each frame_, frame = cap.read()# Convert BGR to HSVhsv = cv.cvtColor(frame, cv.COLOR_BGR2HSV)# define range of blue color in HSVlower_blue = np.array([110,50,50])upper_blue = np.array([130,255,255])# Threshold the HSV image to get only blue colorsmask = cv.inRange(hsv, lower_blue, upper_blue)# Bitwise-AND mask and original imageres = cv.bitwise_and(frame,frame, mask= mask)cv.imshow('frame',frame)cv.imshow('mask',mask)cv.imshow('res',res)k = cv.waitKey(5) & 0xFFif k == 27:breakcv.destroyAllWindows()
五、查找HSV值范围
查找RGB对应的HSV值,以下是代码示例:
import numpy as npimport cv2 as cvgreen = np.uint8([[[0,255,0 ]]])hsv_green = cv.cvtColor(green,cv.COLOR_BGR2HSV)print( hsv_green )