Image Compression and Resize with Python3 and Pillow

process-images.py

from PIL import Image
import getopt
import os
import shutil
import sys

def process_images(argv):
    arg_help = "{0} -i <input_folder> -o <output_folder> -a -c -d <delimiter> -f -s".format(argv[0])

    # Args
    #   -i, --input <input_folder>          change the imput folder
    #   -o, --output <output_folder>        change the output/destination folder
    #   -a, --append <delimiter>            append image width to output file names
    #   -n, --clean                         clean the destination folder before processing
    #   -f, --flatten                       flatten the output destination folder structure (no sub-directories)
    #   -s, --sizes                         generate source set sizes
    input_folder = "./images/"              # image files source
    output_folder = "./compressed_images/"  # image files output
    append = False                          # append image width to output file names
    clean = False                           # clean up output folder before starting
    delimiter = "__"                        # delimits output file naming convention {file name}{delimiter}{resized image width}{file extension}
    flatten = False                         # flatten output folders
    sizes = False                           # create source set sizes

    # Image handling
    compress_quality = 75                   # JPEG compression quality
    compress_level = 7                      # PNG compression level
    optimize = True                         # run image optimization on save
    output_widths = [2880, 1440, 768]       # widths at which the files are resized down to
    file_types = ['.jpg', '.png']           # supported image file types for compression and resizing
    
    try:
        opts, args = getopt.gnu_getopt(argv[1:], "hi:o:acd:fs", ["help", "input=", "output=", "append", "clean", "delimiter=", "flatten", "sizes"])
    except:
        print(arg_help)
        sys.exit(2)
    
    for opt, arg in opts:
        if opt in ("-h", "--help"):
            print(arg_help) # print the help message
            sys.exit(2)
        elif opt in ("-i", "--input"):
            input_folder = os.path.join(arg, "")
        elif opt in ("-o", "--output"):
            output_folder = os.path.join(arg, "")
        elif opt in ("-a", "--append"):
            append = True
        elif opt in ("-c", "--clean"):
            clean = True
        elif opt in ("-d", "--delimit"):
            delimiter = str(arg)
        elif opt in ("-f", "--flatten"):
            flatten = True
        elif opt in ("-s", "--sizes"):
            sizes = True

    # Clean up output directory/files
    if clean :
        try :
            shutil.rmtree(output_folder)
        except FileNotFoundError :
            print("'%s' directory not found" % output_folder)
            pass
        else :
            print("Successfully removed the directory '%s'" % output_folder)

    # (Re)Create our output location
    try :
        os.makedirs(output_folder)
    except OSError:
        print("Creation of the directory '%s' failed" % output_folder)
    else :
        print("Successfully created the directory '%s'" % output_folder)

    # Do the work
    for root, dirs, files in os.walk(input_folder, topdown = True) :
        # Maintain folder structure or flatten?
        if not flatten :
            for dir in dirs :
                full_dir = os.path.join(output_folder, dir)
                try :
                    os.makedirs(full_dir)
                except OSError:
                    print("Creation of the directory '%s' failed" % full_dir)
                else :
                    print("Successfully created the directory '%s'" % full_dir)
        # Process files
        for file in files :
            name, ext = os.path.splitext(file)
            if ext not in file_types :
                print("Skipped file %s, extension not valid" % file)
            else :
                with Image.open(os.path.join(root, file)) as im :
                    original_width = int(im.size[0])
                    original_height = int(im.size[1])
                    max_output_height = original_width * 2

                    # Maintain folder structure or flatten?
                    if flatten :
                        output_destination = output_folder
                    else :
                        output_destination = root.replace(input_folder, output_folder)

                    # Generate output file name
                    if append :
                        output_file = name + delimiter + str(original_width) + ext
                    else :
                        output_file = file

                    # Generate compressed copy of original image
                    try :
                        im.save(os.path.join(output_destination, output_file), im.format, optimize=optimize, quality=compress_quality, compress_level=compress_level)
                    except OSError :
                        print("There was an error saving %s" % output_file)
                    else :
                        print("Image %s successfully saved" % output_file)

                    # Generate resized images for source sets
                    if sizes :
                        for output_width in output_widths:
                            if output_width < original_width :
                                output_file = name + delimiter + str(output_width) + ext # resized image file names are always appended
                                im.thumbnail((output_width, max_output_height)) # We use .thumbnail() because it preserves aspect ratio
                                try :
                                    im.save(os.path.join(output_destination, output_file), im.format, optimize=optimize, quality=compress_quality, compress_level=compress_level)
                                except OSError :
                                    print("There was an error saving %s" % output_file)
                                else :
                                    print("Image %s successfully saved" % output_file)

if __name__ == "__main__":
    process_images(sys.argv)

# Do this:
# Make sure you have Python3 and Pillow installed
# Put all your JPG and PNG images into the <input_folder>
# You can change compression quality with compress_quality variable [for JPEG] and the compress_level variable [for PNG]
# Run script with python3: `python3 imageprocess.py`
# Reference materials:
#   https://pillow.readthedocs.io/en/stable/reference/Image.html
#   https://pillow.readthedocs.io/en/stable/handbook/image-file-formats.html