opencv-python --图像处理

图像处理

颜色转换

颜色转换一般有150多种，常用的有2种BGR ↔ Gray, BGR ↔ HSV

注意
HSV 色调范围[0,179], 饱和度范围[0,255], 值得范围[0,255]

应用场景

目标跟踪
我们可以利用颜色特征，颜色对象，利用HSV更加容易得到，步骤如下：

抽取视频得每一帧
转换BGR->HSV
后去HSV得蓝色得阈值
抽取蓝色图像对象

import cv2 as cv
import numpy as np
cap = cv.VideoCapture(0)
while(1):
    # Take each frame
    _, frame = cap.read()
    # Convert BGR to HSV
    hsv = cv.cvtColor(frame, cv.COLOR_BGR2HSV)
    # define range of blue color in HSV
    lower_blue = np.array([110,50,50])
    upper_blue = np.array([130,255,255])
    # Threshold the HSV image to get only blue colors
    mask = cv.inRange(hsv, lower_blue, upper_blue)
    # Bitwise-AND mask and original image
    res = cv.bitwise_and(frame,frame, mask= mask)
    cv.imshow('frame',frame)
    cv.imshow('mask',mask)
    cv.imshow('res',res)
    k = cv.waitKey(5) & 0xFF
    if k == 27:
        break
cv.destroyAllWindows()

如何获取颜色对应的HSV值?

green = np.uint8([[[0,255,0 ]]])
hsv_green = cv.cvtColor(green,cv.COLOR_BGR2HSV)
print( hsv_green )
[[[ 60 255 255]]]