Image Processing 101

This is a companion repo to my article on image processing basics: https://codewords.recurse.com/issues/six/image-processing-101

Code examples on how to do things with OpenCV on iPython Notebook.

Installation

These instructions are for Mac OSX. For installation on other systems, feel free to use your own choice of a virtual environment for Python. OpenCV for Python requires a local installation of OpenCV on your machine, from which we will create symlinks to in your virtual environment.

step 1

Install virtualenv

step 2

Install OpenCV

# install OpenCV and create symlinks
brew tap homebrew/science
brew install opencv

step 3

Set up virtual environment

# create virtual environment
virtualenv .venv
source .venv/bin/activate

# install requirements, which includes iPython 
pip install -r requirements.txt

step 4

Create symlinks to local OpenCV installation

# for other systems, change the path to site-packages to where your OpenCV installation lies. 

cd .venv/lib/python2.7
ln -s `brew --prefix opencv`/lib/python2.7/site-packages/cv.py cv.py
ln -s `brew --prefix opencv`/lib/python2.7/site-packages/cv2.so cv2.so

Installation for Anaconda

conda install -c https://conda.anaconda.org/menpo opencv3

Development

To run the iPython notebook, which will open up a browser tab with the .ipynb file that you can now work on.

ipython notebook

Common errors

ImportError: No module named cv2

Did you complete step 4 of the installation? Ensure that you are linking to existing cv2.py and cv2.so files.

cv2 still not found even after proper linking

Try restarting the virtual enviroment and iPython.

deactivate
source .venv/bin/activate
ipython notebook

Other errors?

Submit an issue on Github, and I'll do my best to help you out!