photostacker.py

#!/usr/bin/env python3
"""
Lighten-mode stacker, preserves EXIF with earliest timestamp.
Usage: python3 photostacker.py FOLDER [-o out.jpg]

python3 -m pip install numpy Pillow piexif
"""

import sys
import argparse
import re
from pathlib import Path
from datetime import datetime
import numpy as np
from PIL import Image
import piexif

EXTS = {".jpg", ".jpeg", ".png", ".tif", ".tiff", ".webp"}
DT_RE = re.compile(r"^(\d{4}):(\d{2}):(\d{2}) (\d{2}):(\d{2}):(\d{2})")


def parse_dt(b):
    if b is None:
        return None
    s = b.decode(errors="ignore") if isinstance(b, bytes) else b
    m = DT_RE.match(s)
    return datetime(*map(int, m.groups())) if m else None


def load(path):
    """Return (RGB array, piexif dict or None, DateTimeOriginal or None)."""
    img = Image.open(path)
    exif_bytes = img.info.get("exif")
    exif_dict, dt = None, None
    if exif_bytes:
        try:
            exif_dict = piexif.load(exif_bytes)
            dt = parse_dt(exif_dict.get("Exif", {}).get(piexif.ExifIFD.DateTimeOriginal))
        except Exception:
            pass
    arr = np.array(img.convert("RGB"))
    return arr, exif_dict, dt


def main():
    ap = argparse.ArgumentParser()
    ap.add_argument("folder")
    ap.add_argument("-o", "--output", default="stacked.jpg")
    ap.add_argument("-q", "--quality", type=int, default=70)
    args = ap.parse_args()

    folder = Path(args.folder)
    files = sorted(f for f in folder.iterdir() if f.suffix.lower() in EXTS)
    if not files:
        sys.exit(f"No images found in {folder}")

    n = len(files)
    print(f"Stacking {n} images")

    # First image: seed the stack, inherit EXIF as template (camera/lens/GPS/ISO/f/shutter)
    stack, base_exif, min_dt = load(files[0])
    print(f"[1/{n}] {files[0].name}")

    for i, f in enumerate(files[1:], 2):
        arr, _, dt = load(f)
        if arr.shape != stack.shape:
            print(f"\n[{i}/{n}] SKIP (size mismatch): {f.name}")
            continue
        np.maximum(stack, arr, out=stack)
        if dt and (min_dt is None or dt < min_dt):
            min_dt = dt
        print(f"\r[{i}/{n}] {f.name}", end="", flush=True)
    print()

    # Patch datetime to earliest; drop embedded thumbnail (stale)
    if base_exif:
        base_exif["thumbnail"] = None
        base_exif["1st"] = {}
        if min_dt:
            dt_bytes = min_dt.strftime("%Y:%m:%d %H:%M:%S").encode()
            base_exif.setdefault("0th", {})[piexif.ImageIFD.DateTime] = dt_bytes
            base_exif.setdefault("Exif", {})[piexif.ExifIFD.DateTimeOriginal] = dt_bytes
            base_exif["Exif"][piexif.ExifIFD.DateTimeDigitized] = dt_bytes
            print(f"Earliest DateTime: {min_dt}")

    out = Path(args.output)
    save_kwargs = {}
    if out.suffix.lower() in {".jpg", ".jpeg"}:
        save_kwargs = {"quality": args.quality, "optimize": True}
    if base_exif:
        try:
            save_kwargs["exif"] = piexif.dump(base_exif)
        except Exception as e:
            print(f"EXIF dump failed ({e}), saving without EXIF")

    Image.fromarray(stack).save(out, **save_kwargs)
    print(f"Saved: {out}")


if __name__ == "__main__":
    main()

curl https://gist.githubusercontent.com/djosix/79210f54d3a3c67fccf7e07923b2a305/raw/4e97359bc2f574043041371f45f8d0a156fb8bb3/photostacker.py -o ~/.bin/photostacker
chmod +x ~/.bin/photostacker