opencv_installer is a script collected from http://www.pyimagesearch.com/2016/10/24/ubuntu-16-04-how-to-install-opencv/ By using this script, you are admited to take the responsibility of the risk that crash may happen to your system. And this script is only compatible with Ubuntu 16.04.You have to connect to the Internet for the installation.

$ sudo apt update -y
$ sudo apt install git -y
$ cd ~
$ git clone https://github.com/osgee/opencv_installer.git
$ cd opencv_installer
$ source opencv_installer.sh

Then follow the instructions to finish the installation.

$ workon cv
$ python
>>>import cv2
>>>cv2.__version__
[output] 3.1.0	
>>>exit()

If the commands work good, then the installation succeeds, enjoy with opencv!

you can download opencv.zip,opencv_contrib.zip and ippicv_linux_20151201.tgz in advance. Then put them in user's home directory. The script will detect the downloaded files and use them to speed up the installation.