image-resizer.py

#!/usr/bin/env python3
"""
Bulk Image Resizer — Resize all images in a directory to a given max width/height.

Usage:
    python image-resizer.py <input_dir> [--width 800] [--height 600] [--output output_dir]
    python image-resizer.py <input_dir> --percent 50

Options:
    --width W       Max width in pixels (default: 800)
    --height H      Max height in pixels (default: 600)
    --percent P     Resize by percentage (overrides width/height)
    --output DIR    Output directory (default: <input_dir>/resized)
    --keep-aspect   Maintain aspect ratio (default: True)
    --help          Show this help message and exit

Requirements:
    pip install Pillow
"""

import os
import sys
import argparse
from pathlib import Path

try:
    from PIL import Image
except ImportError:
    print("Error: Pillow is required. Install with: pip install Pillow")
    sys.exit(1)

SUPPORTED_EXTENSIONS = {".jpg", ".jpeg", ".png", ".bmp", ".tiff", ".webp"}


def resize_image(img_path: Path, out_path: Path, width: int, height: int,
                 percent: float | None, keep_aspect: bool) -> bool:
    """Resize a single image and save to out_path."""
    try:
        img = Image.open(img_path)
        orig_w, orig_h = img.size

        if percent is not None:
            new_w = int(orig_w * percent / 100)
            new_h = int(orig_h * percent / 100)
        elif keep_aspect:
            ratio = min(width / orig_w, height / orig_h)
            new_w = int(orig_w * ratio)
            new_h = int(orig_h * ratio)
        else:
            new_w, new_h = width, height

        resized = img.resize((new_w, new_h), Image.LANCZOS)
        out_path.parent.mkdir(parents=True, exist_ok=True)
        resized.save(out_path)
        print(f"  ✓ {img_path.name}  {orig_w}x{orig_h} → {new_w}x{new_h}")
        return True
    except Exception as e:
        print(f"  ✗ {img_path.name}  ERROR: {e}")
        return False


def main():
    parser = argparse.ArgumentParser(
        description="Bulk resize images in a directory.",
        formatter_class=argparse.RawDescriptionHelpFormatter,
        epilog=(
            "Examples:\n"
            "  python image-resizer.py ./photos --width 1280 --height 720\n"
            "  python image-resizer.py ./photos --percent 50\n"
            "  python image-resizer.py ./photos --output ./small_photos\n"
        ),
    )
    parser.add_argument("input_dir", help="Directory containing images")
    parser.add_argument("--width", type=int, default=800, help="Max width (default: 800)")
    parser.add_argument("--height", type=int, default=600, help="Max height (default: 600)")
    parser.add_argument("--percent", type=float, help="Resize by percentage (overrides width/height)")
    parser.add_argument("--output", help="Output directory (default: <input_dir>/resized)")
    parser.add_argument("--keep-aspect", action="store_true", default=True, help="Maintain aspect ratio")

    args = parser.parse_args()

    input_path = Path(args.input_dir)
    if not input_path.is_dir():
        print(f"Error: '{args.input_dir}' is not a valid directory.")
        sys.exit(1)

    out_dir = Path(args.output) if args.output else input_path / "resized"

    images = [f for f in input_path.iterdir()
              if f.suffix.lower() in SUPPORTED_EXTENSIONS]

    if not images:
        print(f"No supported images found in '{input_path}'.")
        print(f"Supported: {', '.join(SUPPORTED_EXTENSIONS)}")
        sys.exit(0)

    print(f"Resizing {len(images)} image(s)...")
    success = 0
    for img_path in images:
        if resize_image(img_path, out_dir / img_path.name,
                        args.width, args.height, args.percent, args.keep_aspect):
            success += 1

    print(f"\nDone: {success}/{len(images)} resized → {out_dir}")


if __name__ == "__main__":
    main()