subplot-mosaic-8.py

import matplotlib.pyplot as plt

image = plt.imread("gardens.jpg")

# Create a figure
fig, axs = plt.subplot_mosaic(
    [
        ["colour", "colour", "colour"],
        ["colour", "colour", "colour"],
        ["colour", "colour", "colour"],
        ["red", "green", "blue"],
    ]
)

axs["colour"].imshow(image)
axs["colour"].axis("off")

# Create red channel image. I'll keep these images as 3D arrays
# and set the second and third layers, which represent the green
# and blue channels, to 0
image_red = image.copy()
image_red[:, :, 1:] = 0

# Same for the green image, but now the first and third layers
# are set to 0
image_green = image.copy()
image_green[:, :, 0] = 0
image_green[:, :, 2] = 0

image_blue = image.copy()
image_blue[:, :, 0:2] = 0

# Plot the separate channels
axs["red"].imshow(image_red)
axs["red"].axis("off")
axs["green"].imshow(image_green)
axs["green"].axis("off")
axs["blue"].imshow(image_blue)
axs["blue"].axis("off")

plt.show()