Getting Started with Python OpenCV in a JupyterLab Notebook

How to start with Python OpenCV in a JupyterLab Notebook.

If you want see how to install Python and OpenCV on various OS check these videos:
- for Windows https://www.youtube.com/watch?v=Qfbxw6Ssyko
- for macOS https://www.youtube.com/watch?v=nO3csmVyoOQ
- for Ubuntu Linux https://www.youtube.com/watch?v=0SeqpTab73U

Create and activate a venv on Windows:
python -m venv work
work\Scripts\activate

Create and activate a venv on Linux and macOS:
python3 -m venv work
source work/bin/activate

Install libraries:
pip install opencv-python-headless
pip install matplotlib
pip install jupyterlab

Start JupyterLab:
jupyter lab

Code used in the video (change the image name to match the image you have on your computer):
import cv2
from matplotlib import pyplot as plt

print(cv2.__version__)

img = cv2.imread("clouds.jpg")
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

plt.imshow(gray, cmap = 'gray')
plt.title("Over the Clouds - gray")

plt.imshow(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
plt.title("Over the Clouds - original color image")

f = plt.figure(figsize=(15, 15))
f.add_subplot(1, 2, 1)
plt.imshow(gray, cmap = 'gray')
plt.title("Over the Clouds - gray")

f.add_subplot(1, 2, 2)
plt.imshow(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))
plt.title("Over the Clounds - original color image")