Opencv image simple operation

批量操作

#对文件进行批量重命名
 import os
path=“C:\Users\Lenovo\Desktop/first.text” 
filelist = os.listdir(path)
i = 0
for file in filelist:
	old = os.path.join(path,file)
	filetype = os.path.splitext(file)[1]
		i = i+1;
		new = os.path.join(path,str(i)+filetype)
		os.rename(old,new)

读取图片

>>> import cv2    #导入opencv包
>>> img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')   #绝对路径，这里为'/'
>>> cv2.imshow('test',img)
>>> cv2.waitKey(0)   #让图像不会一闪而过

保存图片

import cv2
>>> img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
>>> cv2.imshow('test',img)
>>> cv2.imwrite('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.png',img)  #将图片转换为png格式保存
True
>>> cv2.imwrite('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.bmp',img)#将图片转换为bmp格式保存
True
>>> cv2.waitKey(0)

截取图像

import cv2
>>> img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
>>> frame=img[300:600,300:600]   #截取部分图像为300:600行，300:600
>>> cv2.imshow('test',frame)
>>> cv2.waitKey(0)

翻转图片
通过flipcode控制图片翻转方向

import cv2
img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
flipcode1=1   #大于0时图片左右翻转
flipcode2=0   #等于0时上下翻转
flipcode3=-1  #小于0时先上下再左右翻转
img1=cv2.flip(img,flipcode1)
img2=cv2.flip(img,flipcode2)
img3=cv2.flip(img,flipcode3)
cv2.imshow('test1',img1)
cv2.imshow('test2',img2)
cv2.imshow('test3',img3)
cv2.waitKey(0)

图片的缩放

import cv2
img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
img1=cv2.resize(img,(600,600))
img2=cv2.resize(img,None,fx=0.6,fy=0.6)  #None的位置原本用于输出尺寸，现在设置缩放因子fx(水平轴),fy(竖直轴).
cv2.imshow('test',img)
cv2.imshow('test1',img1)
cv2.imshow('test2',img2)
cv2.imwrite('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg',img1)
cv2.waitKey(0)

转换为灰度图像

import cv2
img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
cv2.imshow('BGR',img)
img1=cv2.cvtColor(img,cv2.COLOR_BGR2RGB)   #将图像格式转换为RGB，但opencv按照BGR读取图片，故转换为RGB后不像原图
cv2.imshow('RGB',img1)
img2=cv2.cvtColor(img1,cv2.COLOR_RGB2GRAY)   #将图像转换为灰度图像
cv2.imshow('GRAY',img2)
cv2.waitKey(0)

在一个窗口中显示两张图片

import cv2
import numpy as np
img=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
img1=cv2.imread('D:/Peggy/v2-a71a40410bbc2789cc3f1c0cad413bb8_r.jpg')
imgs=np.hstack([img,img1])    #水平方向
#imgs=np.vstack([img,img1]) #竖直方向
cv2.imshow('mutil_pic',imgs)
cv2.waitKey(0)