8.1 Image Basics

Consider the following example that uses the image four-circles.jpg .

import matplotlib.pyplot as plt

img = plt.imread('./four-circles.jpg')    # Load the image
plt.imshow(img)                           # Display the image
plt.axis('off')                           # Don't show the axes
plt.show()

print(img.shape)                          # What type of variabe is 'img'

# (1000, 1000, 3)

We can see how matplotlib stores image information by looking at the details of img. The image is stored as a \(1000 \times 1000 \times 3\), np array! The image is made up of \(3\) stacked numpy \(1000 \times 1000\) arrays.
Each of these arrays carry information about the RGB (red, green, blue) components (‘channels’). We can check this by just visualizing the ‘layers’ or ‘channels’ separately.

Note that other packages (e.g. skimage) might store the same information in a different format (e.g. \(3\times 1000 \times 1000\)).