can't install opencv on my pi

Question

I'm an absolute Raspberry Pi newbie. My intention is to get some camera vision project working for which I need OpenCV3.3's dnn Python module.

I've found here a description of how OpenCV can be installed with pip but I'm getting the following error:

$ pip install opencv-contrib-python
Collecting opencv-contrib-python
  Could not find a version that satisfies the requirement opencv-contrib-python (from versions: )
No matching distribution found for opencv-contrib-python

can anyone help me further here?

Answer 1

You can try the following:

sudo apt-get install libopencv-dev python3-opencv

You might try also to compile the library by yourself by downloading the source code from the git repository. Note that from the link a version 4 is available. You will have to solve a lot of dependencies by yourself by installing apt packages.

Raspberry3 model B should have enough memory to compile it (it requires a lot of time) (RPi2 maybe, RPi1 I do not think so) but it's not garanteed. If I remember correctly I compiled it but after a couple of times it went out of memory).

In this link here is described a much longer step-by-step tutorial for Ubuntu and here specific for the raspberry to compile the library opencv by yourself but I think the first command is enough and dependencies should be installed automatically (if it works on aspbian).

Answer 2

You should not have to compile - there should be a package in the repository. I have never used it, but apt-cache search opencv will show all the candidates.

I expect sudo apt install python-opencv is what you want.

If you are a beginner you almost certainly don't want the contrib package.

Answer 3

I ended up compiling OpenCV 3.4.4 from source as described on https://www.pyimagesearch.com/2018/05/28/ubuntu-18-04-how-to-install-opencv/ - the instructions are for Ubuntu but it worked just fine the same way on my Rasperry Pi running Raspian 9. I ended up with:

$ python
Python 3.5.3 (default, Sep 27 2018, 17:25:39) 
[GCC 6.3.0 20170516] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import cv2
>>> cv2.__version__
'3.4.4'
>>> quit()