robo-matplotlib-numpy-image-rgb-viz

main.py

# Import some packages from matplotlib
import matplotlib.image as mpimg
import matplotlib.pyplot as plt
# Import the "numpy" package for working with arrays
import numpy as np
# Uncomment the next line for use in a Jupyter notebook
#%matplotlib inline

# Define the filename, read and plot the image
filename = 'sample.jpg'
image = mpimg.imread(filename)

# Note: we use the np.copy() function rather than just saying red_channel = image
# because in Python, such a statement would set those two arrays equal to each other
# forever, meaning any changes made to one would also be made to the other!
red_channel = np.copy(image)
# Note: here instead of extracting individual channels from the image
# I'll keep all 3 color channels in each case but set the ones I'm not interested 
# in to zero.  
red_channel[:,:,[1, 2]] = 0 # Zero out the green and blue channels
green_channel = np.copy(image)
green_channel[:,:,[0, 2]] = 0 # Zero out the red and blue channels
blue_channel = np.copy(image)
blue_channel[:,:,[0, 1]] = 0 # Zero out the red and green channels
fig = plt.figure(figsize=(12,3)) # Create a figure for plotting
plt.subplot(131) # Initialize subplot number 1 in a figure that is 3 columns 1 row
plt.imshow(red_channel) # Plot the red channel
plt.subplot(132) # Initialize subplot number 2 in a figure that is 3 columns 1 row
plt.imshow(green_channel)  # Plot the green channel
plt.subplot(133) # Initialize subplot number 3 in a figure that is 3 columns 1 row
plt.imshow(blue_channel)  # Plot the blue channel
plt.show()