Adding a border to and Image in my code

Help, I need to put a border on the image displayed from the code below. How do I do this? The code below pulls up the image, and now i need a border. Help.. All of this code is Python

# -*- coding: utf-8 -*-
'''
LoganCaroline_1_4_7: Merge images
'''
import matplotlib.pyplot as plt 
import os.path
import numpy as np      # “as” lets us use standard abbreviations

'''Read the image data'''
# Get the directory of this python script
directory = os.path.dirname(os.path.abspath(__file__)) 
# Build an absolute filename from directory + filename
filename = os.path.join(directory, 'family1.jpg')
# Read the image data into an array
img = plt.imread(filename)

'''Show the image data'''
# Create figure with 1 subplot
fig, ax = plt.subplots(1, 1)
# Show the image data in a subplot
ax.imshow(img, interpolation='none')
# Show the figure on the screen
fig.show()

Answer

Just create a slightly larger array that is black and fill the central pixels with your image.

import numpy as np
import matplotlib.pyplot as plt

def frame_image(img, frame_width):
    b = frame_width # border size in pixel
    ny, nx = img.shape[0], img.shape[1] # resolution / number of pixels in x and y
    if img.ndim == 3: # rgb or rgba array
        framed_img = np.zeros((b+ny+b, b+nx+b, img.shape[2]))
    elif img.ndim == 2: # grayscale image
        framed_img = np.zeros((b+ny+b, b+nx+b))
    framed_img[b:-b, b:-b] = img
    return framed_img

img = np.random.rand(456, 333, 3)
fig, (ax1, ax2) = plt.subplots(1,2)
ax1.imshow(img, interpolation='none')
ax2.imshow(frame_image(img, 20), interpolation='none')
plt.show()