Add frame directory comparison tool

tools/compare_frame_dirs.py

@@ -0,0 +1,29 @@
+"""Compare two directories of same-sized PNG frames."""
+
+import argparse
+from pathlib import Path
+
+import numpy as np
+from PIL import Image
+
+
+parser = argparse.ArgumentParser()
+parser.add_argument("a", type=Path)
+parser.add_argument("b", type=Path)
+parser.add_argument("--frames", type=int, required=True)
+args = parser.parse_args()
+
+rows = []
+for index in range(args.frames):
+    a = np.asarray(Image.open(args.a / f"frame_{index:04d}.png")).astype(np.int16)
+    b = np.asarray(Image.open(args.b / f"frame_{index:04d}.png")).astype(np.int16)
+    diff = np.abs(a - b)
+    rows.append((index, int(diff.max()), float(diff.mean()), float(np.percentile(diff, 99))))
+
+print({
+    "frames": args.frames,
+    "max": max(row[1] for row in rows),
+    "mean": sum(row[2] for row in rows) / len(rows),
+    "top_max": sorted(rows, key=lambda row: row[1], reverse=True)[:10],
+    "top_mean": sorted(rows, key=lambda row: row[2], reverse=True)[:10],
+})