Install openCV on Ubuntu 16.04

I was installing openCV following the instruction from the first google search:
          https://www.learnopencv.com/install-opencv3-on-ubuntu/

But I met the following problems so far.

sudo apt-get install git gfortran

error:
The following packages have unmet dependencies:
 gfortran : Depends: gfortran-5 (>= 5.3.1-3~) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

solution:

sudo add-apt-repository ppa:ubuntu-toolchain-r/test
sudo apt-get update
sudo apt-get install gfortran-5

Now do it again and it works.

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sudo apt-get install libjpeg8-dev libjasper-dev libpng12-dev

error:
The following packages have unmet dependencies:
 libjasper-dev : Depends: libjasper1 (= 1.900.1-debian1-2.4ubuntu1) but 1.900.1-debian1-2.4ubuntu1.1 is to be installed
E: Unable to correct problems, you have held broken packages.

solution:

sudo add-apt-repository "deb http://security.ubuntu.com/ubuntu xenial-security main"
sudo apt update
sudo apt install libjasper1 libjasper-dev

Now do it again and it works.

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~$ sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev

E: Could not get lock /var/lib/dpkg/lock - open (11: Resource temporarily unavailable) 

E: Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?

Solution:

sudo rm /var/lib/apt/lists/lock

sudo rm /var/cache/apt/archives/lock
sudo rm /var/lib/dpkg/lock

~$ sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev

E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem.

~$ sudo dpkg --configure -a

Do it again and worked:

~$ sudo apt-get install libavcodec-dev libavformat-dev libswscale-dev libdc1394-22-dev

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~$ sudo apt-get install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev

error:

The following packages have unmet dependencies:

 libgstreamer-plugins-base0.10-dev : Depends: libglib2.0-dev but it is not going to be installed

 libgstreamer0.10-dev : Depends: libglib2.0-dev but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

Solution:

Install the dependency libglib2.0-dev:
sudo apt-get install libglib2.0-dev libglib2.0-0=2.48.0-1ubuntu4

Do it again and worked:
~$ sudo apt-get install libgstreamer0.10-dev libgstreamer-plugins-base0.10-dev

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sudo apt-get install qt5-default libgtk2.0-dev libtbb-dev
I jumped over qt5-default, too many dependencies...so just:

~$ sudo apt-get install libgtk2.0-dev libtbb-dev

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sudo apt-get install python-dev python-pip python3-dev python3-pip




errors:

The following packages have unmet dependencies:

 python3-pip : Depends: python-pip-whl (= 8.1.1-2) but 8.1.1-2ubuntu0.4 is to be installed

               Recommends: python3-setuptools but it is not going to be installed

               Recommends: python3-wheel but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

solution:

Don't know yet...I jumped over python3-pip for now.

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OK finally cmake...but I got errors. After trying a lot to install some dependencies like qt5, I still couldn't get rid of the errors. I found the official website has a tutorial about installation:

            

                https://docs.opencv.org/trunk/d2/de6/tutorial_py_setup_in_ubuntu.html

Note that you have to delete ./build directory and create a new folder and do:

$ cmake ../

...and it worked!

..............

-- -----------------------------------------------------------------

-- 

-- Configuring done

-- Generating done

 ...................

ref:

https://www.learnopencv.com/install-opencv3-on-ubuntu/

https://askubuntu.com/questions/720948/problems-installing-gfortran

https://github.com/opencv/opencv/issues/8622

https://askubuntu.com/questions/15433/unable-to-lock-the-administration-directory-var-lib-dpkg-is-another-process
https://askubuntu.com/questions/884413/unable-to-install-libgtk2-0-dev-on-ubuntu-16-04/886022

https://docs.opencv.org/trunk/d2/de6/tutorial_py_setup_in_ubuntu.html
https://docs.opencv.org/trunk/d7/d9f/tutorial_linux_install.html