If we want to work with an image the first job is to read it in. Thinking back to the Game of Life you can probably imagine that there are multiple ways of storing an image on disk, and you'd be right. Common formats include PNG, JPEG, BMP and GIF but there are many more (e.g. Wikipedia lists around 70). We don't want to write low level code to read even one format, much less 70, so we'll use a library to do that for us. Python has more than one option, but we'll use the Python Imaging Library (PIL ). This means you'll need to install it.
For Windows this is a simple process of downloading the appropriate binary file and running it. Appropriate here means the one matching your Python version.
For Linux, use your package manager, it will know all about PIL.
For Mac I am unsure. Some online sources say PIL is already included in the standard python distribution, others give installation instructions. I don't have a Mac to test, but hopefully these search results will guide you.
You'll know you have successfully installed it when this one-line program runs without error:
from PIL import ImageThese notes will show you the subset of PIL operations we'll be using but if you want to explore the Python Imaging Library Handbook is quite thorough. PIL is a "small" library, but we'll barely scratch the surface of what it offers.