Cropping Bulk Images Using Python.

I was working on getting post headers for my post on this blog. I had couple of images from unsplash. But the header for the post need to be a little more horizontal. So I had to crop the images to fit accordingly.

Pillow to the Rescue

So I checked online and found pillow. This awesome library has crop function which does exactly what I wanted. Here is what it does.

Returns a rectangular region from this image. The box is a 4-tuple defining the left, upper, right, and lower pixel coordinate.

Note: Prior to Pillow 3.4.0, this was a lazy operation.

Parameters:	box – The crop rectangle, as a (left, upper, right, lower)-tuple.
Return type:	Image
Returns:	An Image object.

This function takes 4 parameters. These are the coordinates for left-top and righ-bottom pixels.

left, upper, right, and lower 

Code Snippet

from PIL import Image
import os

#
# Pick up all the images from the directory
#
files_in_directory = os.listdir('images/input_unsplash/')

# we are using the counter for the output image name.
counter = 1

# process each file.
for every_file in files_in_directory:

    inbound_image_to_process = "images/input_unsplash/" + every_file
    image_to_process = Image.open(inbound_image_to_process)

    img_width, img_height = image_to_process.size
    print img_width, img_height, float(img_width / img_height)

    # Check if the images is not already `horizontal` (width way larger than height - aka panorama).
    if float(img_width / img_height) <= 1.0:

        left = img_width / 2
        top = img_height / 2
        right = 3 * img_width / 3
        bottom = 3 * img_height / 3

        print left, top, right, bottom

        # Check if the image height is not less than what we want.
        if img_height > 1200:
            cropped_example = image_to_process.crop((0, top, right, bottom))

            # Enable to check the image
            # cropped_example.show()

        # Large Images can be cropped.
        else:
            cropped_example = image_to_process.crop((0, top, right, img_height))
            # cropped_example.show()

        # Finally save them as jpeg.
        cropped_example.save("images/output/unsplash-image-" + str(counter) + ".jpg", "JPEG")
        counter = counter + 1

Useful Links

• Pillow Image Crop
• Pillow