10. Coding a Blue Screen

OpenCV

OpenCV is a popular computer vision library that has meany built in tools for image analysis and understanding!

Note: In the example above and in later examples, I'm using my own Jupyter notebook and sets of images stored on my personal computer. You're encouraged to set up a similar environment and use images of your own to practice! You'll also be given some code quizzes (coming up next), with images provided, to practice these techniques.

Why BGR instead of RGB?

OpenCV reads in images in BGR format (instead of RGB) because when OpenCV was first being developed, BGR color format was popular among camera manufacturers and image software providers. The red channel was considered one of the least important color channels, so was listed last, and many bitmaps use BGR format for image storage. However, now the standard has changed and most image software and cameras use RGB format, which is why, in these examples, it's good practice to initially convert BGR images to RGB before analyzing or manipulating them.

Changing Color Spaces

To change color spaces, we used OpenCV's cvtColor function, whose documentation is here.