{
  "image_path": "testdata/ringgrid.png",
  "polarity": "Dark",
  "radius_hint": 12.0,
  "frst": {
    "radii": [8, 10, 12, 14, 16],
    "alpha": 2.0,
    "gradient_threshold": 2.0
  },
  "nms": {
    "radius": 12,
    "threshold": 0.01,
    "max_detections": 30
  },
  "output_dir": "output"
}
