Image Processing is most commonly termed as 'Digital Image Processing' and the domain in which it is frequently used is 'Computer Vision'. Don't be confused - we are going to talk about both of these terms and how they connect. Both Image Processing algorithms and Computer Vision (CV) algorithms take an image as input; however, in image processing, the output is also an image, whereas in computer vision the output can be some features/information about the image.
$ pip install opencv-python
$ brew install opencv3 --with-contrib --with-python3
$ sudo apt-get install libopencv-dev python-opencv