import cv2

import numpy as np

img = cv2.imread('1.jpg')

cv2.imshow('image',img)

k = cv2.waitKey(0)

"把一个RGB图片看成一个3维的数组"

img2 = img[20:300, 100:400]

cv2.imshow('img2',img2)

k = cv2.waitKey(0)

"快速矩阵运算是numpy的优点，批量像素修改不需要使用循环，使用矩阵运算"

px=img[100,100]

print(px)

blue = img[100,100,0]

print(blue)

img[100:200,100:200]=[255,255,255]

print(img[101,101])

cv2.imshow('image',img)

k = cv2.waitKey(0)

img = cv2.imread('1.jpg')

" img.shape可以获得图像的形状，返回值是一个包含行数，列数，通道数的元组"

" 灰度图，返回值仅有行数和列数"

print(img.shape)

"img.size可以返回图像的像素数目"

print(img.size)

"图像的特定区域  拷贝操作"

logo = img[30:130, 330:430]

img[100:200,100:200] = logo

cv2.imshow('image',img)

k = cv2.waitKey(0)

"拆分及合并图像通道  对RGB三个通道分别操作"

"cv2.split()是比较耗时的操作，能用numpy就尽量使用"

r,g,b=cv2.split(img)#拆分

#img=cv2.merge(r,g,b)#合并

cv2.imshow('b',b)

k = cv2.waitKey(0)

img[:,:,2]=0

cv2.imshow('img',img)

k = cv2.waitKey(0)