Batch Image Resizer
This utility processes a directory of images, resizing them to fit within specified dimensions while maintaining their aspect ratio. It handles format conversion and creates the output directory if it doesn't exist.
Modules Used:
- Pillow: For opening, resizing, and saving images.
- argparse: To handle command-line arguments for dimensions and paths.
- pathlib: For robust file path handling.
The Code
Save this as resizer.py.
import argparse
from pathlib import Path
from PIL import Image
def resize_images(input_dir, output_dir, max_width, max_height, output_format):
input_path = Path(input_dir)
output_path = Path(output_dir)
# Create output directory if it doesn't exist
output_path.mkdir(parents=True, exist_ok=True)
supported_extensions = {'.jpg', '.jpeg', '.png', '.bmp', '.gif', '.webp'}
# Find images
files = [f for f in input_path.iterdir() if f.is_file() and f.suffix.lower() in supported_extensions]
print(f"Found {len(files)} images in '{input_dir}'")
for file in files:
try:
with Image.open(file) as img:
# Use thumbnail() to resize in place, maintaining aspect ratio
# It will not scale up images smaller than the target size
img.thumbnail((max_width, max_height))
# Determine output filename
new_suffix = f".{output_format}" if output_format else file.suffix
save_name = file.stem + new_suffix
save_path = output_path / save_name
# Handle transparency for JPEG (convert RGBA to RGB)
if new_suffix.lower() in ['.jpg', '.jpeg'] and img.mode in ('RGBA', 'P'):
img = img.convert('RGB')
img.save(save_path)
print(f"Processed: {file.name} -> {save_name} ({img.size[0]}x{img.size[1]})")
except Exception as e:
print(f"Error processing {file.name}: {e}")
if __name__ == "__main__":
parser = argparse.ArgumentParser(description="Batch Image Resizer")
parser.add_argument("input", help="Input directory containing images")
parser.add_argument("output", help="Output directory for resized images")
parser.add_argument("--width", type=int, default=800, help="Maximum width (default: 800)")
parser.add_argument("--height", type=int, default=800, help="Maximum height (default: 800)")
parser.add_argument("--format", help="Convert to specific format (e.g., jpg, png)")
args = parser.parse_args()
resize_images(args.input, args.output, args.width, args.height, args.format)Usage
# Resize images to fit within 800x800 (default)
python resizer.py ./raw_photos ./web_ready
# Resize to 200x200 thumbnails and convert to PNG
python resizer.py ./photos ./thumbnails --width 200 --height 200 --format png