Vertically stack two images

stack_vertical_images.py

# ref https://stackoverflow.com/questions/53876007/how-to-vertically-merge-two-images/53882483

# usage 
# $ python vertical_stack.py </path/to/top/figure> </path/to/bottom/figure> </directory/to/output/figure> <output_file_name_with_extension>
# <output_file_name_with_extension> is optional, default to vertical_stack.png

# example
# $ python stack_vertical_images.py /Users/foo/bar/top_figure.png /Users/foo/bar/button_figure.png /Users/output vertical_stack.png

# NOTE
# there is no ending slash / in </directory/to/output/figure> !!

from PIL import Image
import sys

images_list = [sys.argv[1], sys.argv[2]]
imgs = [Image.open(i) for i in images_list]

try:
    image_name = sys.argv[4]
except:
    image_name = "vertical_stack.png"

min_img_width = min(i.width for i in imgs)

total_height = 0
for i, img in enumerate(imgs):
    # If the image is larger than the minimum width, resize it
    if img.width > min_img_width:
        imgs[i] = img.resize((min_img_width, int(img.height / img.width * min_img_width)), Image.ANTIALIAS)
    total_height += imgs[i].height

img_merge = Image.new(imgs[0].mode, (min_img_width, total_height))
y = 0
for img in imgs:
    img_merge.paste(img, (0, y))

    y += img.height
img_merge.save(f"{sys.argv[3]}/{image_name}")