output_path.parent.mkdir(parents=True, exist_ok=True)
if not cv.imwrite(str(output_path), edges):
    raise SystemExit(f"could not write image: {output_path}")

edge_pixels = cv.countNonZero(edges)
edge_percent = edge_pixels / edges.size * 100

print(f"input: {input_path}")
print(f"image size: {gray.shape[1]}x{gray.shape[0]}")
print("thresholds: 80/160")
print(f"edge pixels: {edge_pixels} ({edge_percent:.2f}%)")
print(f"output: {output_path}")