Python is a very powerful scripting language and you will be pleasantly surprised to find that a lot of the common functions you would want to build are available to you in library form. The Python ecosystem is very alive and full of libraries.

Point in case, today I will show you how to easily build a Python script that will resize all of the images in a folder to the dimensions you choose.

This is how you will invoke the script:

python image_resizer.py -d 'PATHHERE' -w 448 -h 200

First let’s import what we need in order for this script to work:

import os, getopt, sys
from PIL import Image

• OS, lets us access functions that will interact with our computer, in this case, fetching files from a folder.
• getopt, lets us easily access command line arguments passed in by the end user.
• Image, will allow us to invoke the resize function that will perform the heavy lifting of the application.

Command Line Arguments

Next, let’s go ahead and process the command line arguments. We also have to take into account the slight chance that an argument is missing. In this case, we’ll display an error message and terminate the program.

# Let's parse the arguments.
opts, args = getopt.getopt(sys.argv[1:], 'd:w:h:')

# Set some default values to the needed variables.
directory = ''
width = -1
height = -1

# If an argument was passed in, assign it to the correct variable.
for opt, arg in opts:
    if opt == '-d':
        directory = arg
    elif opt == '-w':
        width = int(arg)
    elif opt == '-h':
        height = int(arg)

# We have to make sure that all of the arguments were passed.
if width == -1 or height == -1 or directory == '':
    print('Invalid command line arguments. -d [directory] -w [width] -h [height] are required')

    # If an argument is missing exit the application.
    exit()

The comments above are pretty self explanatory. We parse the arguments, set variables with defaults values for usage, and assign them. If one or more variable is missing, we terminate the application.

Great, now we can focus on the purpose of this script. Let’s fetch each image in the folder and process it.

# Iterate through every image given in the directory argument and resize it.
for image in os.listdir(directory):
    print('Resizing image ' + image)

    # Open the image file.
    img = Image.open(os.path.join(directory, image))

    # Resize it.
    img = img.resize((width, height), Image.BILINEAR)

    # Save it back to disk.
    img.save(os.path.join(directory, 'resized-' + image))

print('Batch processing complete.')

The Image.open function is returning an Image object, which in turn lets us apply the resize method on it. We use the Image.BILINEAR algorithm, for simplicity.

And that’s all there is to it. As you can see Python is quite an agile language and allows developers to focus on solving business needs.

The post Batch Image Re-Sizing and Processing with Python 2.x appeared first on Python Central.