image_resize.py

#!/usr/bin/env python

########################################################################
# image_resize.py: Image Resizer
#
#  Description:
#  This Python script resizes images in a specified directory to a given size.
#  It supports JPEG and PNG formats. The script walks through the source directory,
#  resizes each image, and saves it to the output directory. This version includes
#  error handling for environments where the PIL library is not installed.
#
#  Author: id774 (More info: http://id774.net)
#  Source Code: https://github.com/id774/scripts
#  License: The GPL version 3, or LGPL version 3 (Dual License).
#  Contact: idnanashi@gmail.com
#
#  Usage:
#      image_resize.py <size> <source_directory> <output_directory>
#
#  Example:
#      image_resize.py 300 ./images ./resized
#
#  Requirements:
#  - Python Version: 3.2 or later
#  - Dependencies: Pillow
#
#  Version History:
#  v1.4 2025-07-01
#       Standardized termination behavior for consistent script execution.
#  v1.3 2025-06-23
#       Unified usage output to display full script header and support common help/version options.
#  v1.2 2025-04-14
#       Unify error and info message formatting with stderr and prefix tags.
#  v1.1 2024-01-11
#      Added error handling for PIL library not installed.
#  v1.0 2023-12-24
#      Initial release. Basic functionality for resizing images.
#
########################################################################

import argparse
import os
import sys

# Importing PIL library and handling errors if not installed
try:
    from PIL import Image
except ImportError as e:
    libraries_installed = False
else:
    libraries_installed = True

def usage():
    """ Display the script header as usage information and exit. """
    script_path = os.path.abspath(__file__)
    in_header = False
    try:
        with open(script_path, 'r', encoding='utf-8') as f:
            for line in f:
                if line.strip().startswith('#' * 10):
                    if not in_header:
                        in_header = True
                        continue
                    else:
                        break
                if in_header and line.startswith('#'):
                    if line.startswith('# '):
                        print(line[2:], end='')
                    else:
                        print(line[1:], end='')
    except Exception as e:
        print("Error reading usage information: %s" % str(e), file=sys.stderr)
        sys.exit(1)
    sys.exit(0)

def resize_file(size, filename, outpath):
    """ Resizes an image to a square of the given size. """
    img = Image.open(filename, 'r')
    img.thumbnail((size, size))
    img.save(outpath)

def is_image_file(filename):
    """ Checks if a file is a JPEG or PNG image using Pillow. """
    try:
        with Image.open(filename) as img:
            return img.format.lower() in ['jpeg', 'png']
    except IOError:
        return False

def read_dir(size, src, out):
    """ Reads the source directory and resizes images found there. """
    for root, _, files in os.walk(src):
        for filename in files:
            fullname = os.path.join(root, filename)
            if is_image_file(fullname):
                outpath = os.path.join(out, filename)
                print("[INFO] Resize: {0}".format(filename))
                resize_file(size, fullname, outpath)

def parse_args():
    """ Parses command line arguments. """
    parser = argparse.ArgumentParser(
        description="Resize images in a directory.")
    parser.add_argument("size", type=int, help="Size of the output image.")
    parser.add_argument("src", help="Source directory of images.")
    parser.add_argument("out", help="Output directory for resized images.")
    return parser.parse_args()

def main():
    """ Main function to execute the script. """
    if not libraries_installed:
        print("[ERROR] Required libraries not installed.", file=sys.stderr)
        sys.exit(1)

    args = parse_args()
    read_dir(args.size, args.src, args.out)
    return 0


if __name__ == '__main__':
    if len(sys.argv) < 4 or sys.argv[1] in ('-h', '--help', '-v', '--version'):
        usage()

    if sys.version_info < (3, 2):
        print("[ERROR] This script requires Python 3.2 or later.", file=sys.stderr)
        sys.exit(9)

    sys.exit(main())