详解Python中常用的图片处理函数的使用

cvtColor函数

这个函数有两个参数

1，src 要进行变换的原图像

2，code 转换代码标识

例子：

import cv2
image=cv2.imread("ddd.jpg")
image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA)
cv2.imshow("",image1)
cv2.waitKey(0)
if __name__ == '__main__':
   print()

split()和merge()

例子：

import cv2
image=cv2.imread("ddd.jpg")
# image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA)
r,g,b=cv2.split(image)
cv2.imshow("r",r)
cv2.imshow("g",g)
cv2.imshow("b",b)
cv2.waitKey(0)
if __name__ == '__main__':
   print()

import cv2
image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg")
# image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA)
r,g,b=cv2.split(image)
cv2.imshow("r",r)
cv2.imshow("g",g)
cv2.imshow("b",b)
image1=cv2.merge([b,g,r])
cv2.imshow("image",image1)
cv2.waitKey(0)
if __name__ == '__main__':
   print()

threshold()函数

ret，image= cv2.threshold(src,thresh,maxval,type)

实现二值化的重要函数

参数说明

src 输入图像

image 输出图像

thresh 阀值

maxval 当像素值超过阀值thresh 时赋值为maxval

type 当像素值小于阀值thresh的时赋值为type type可填下面5种类型的参数

例子：

import cv2
image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg")
# image1=cv2.cvtColor(image,cv2.COLOR_BGR2BGRA)
# r,g,b=cv2.split(image)
# cv2.imshow("",r)
# cv2.imshow("",g)
# cv2.imshow("",b)
# image1=cv2.merge([b,g,r])
# cv2.imshow("image",image1)

ret,image1=cv2.threshold(image,127,255,cv2.THRESH_BINARY)
ret1,image2=cv2.threshold(image,127,255,cv2.THRESH_BINARY_INV)
# ret2,image3=cv2.threshold(image,127,255,cv2.THRESH_TRIANGLE)
ret3,image4=cv2.threshold(image,127,255,cv2.THRESH_TOZERO)
ret4,image5=cv2.threshold(image,127,255,cv2.THRESH_TOZERO_INV)

cv2.imshow("1",image1)
cv2.imshow("2",image2)
# cv2.imshow("3",image3)
cv2.imshow("4",image4)
cv2.imshow("5",image5)
cv2.waitKey(0)
if __name__ == '__main__':
   print()

自定义threshold函数进行二值化

import cv2
image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg")
width,height,n=image.shape
image2=image.copy()
for i in range(width):
   for j in range(height):
       for channel in range(3):
           if image2[i][j][channel]>127:
               image2[i][j][channel]=255
           else:
               image2[i][j][channel]=0
cv2.imshow('',image2)
cv2.waitKey(0)

if __name__ == '__main__':
   print()

这个速度很慢对于分辨率太高的图

色度函数applyColorMap

import cv2
image=cv2.imread("/home/dfy/Pictures/Camera_photo/Camera_photo/sss.jpg")
image_color_map=cv2.applyColorMap(image,cv2.COLORMAP_JET)
cv2.imshow("im",image_color_map)
cv2.waitKey(0)

if __name__ == '__main__':
   print()

来源：https://segmentfault.com/a/1190000041237887