Just a quick example of how to resize an INCREDIBLY large image.

imgresizr.py

from PIL import Image

# 8 Inches
basewidth = 768

# This is the size of the image I was working with... this line will supress warnings about the image being too big
Image.MAX_IMAGE_PIXELS = 556631040

# Open the image
img = Image.open("original.png")

# Calculate the width % and height size based on the fixed width
# To do fixed height you would simply flip things around
wpercent = (basewidth / float(img.size[0]))
hsize = int((float(img.size[1]) * float(wpercent)))

# Resize the image using anti-aliasing
img = img.resize((basewidth, hsize), Image.ANTIALIAS)

# Save the image
img.save("/Users/acrowder/Desktop/resized.png")

requirements.txt

Pillow