{
  "content": {
    "char_set": "ABCDEFGHJKMNPQRSTUVWXYZ23456789",
    "text_length": 4
  },
  "render": {
    "canvas_size": [280, 100],
    "bg_color": [255, 255, 255],
    "fonts": ["/usr/share/fonts/truetype/dejavu/DejaVuSans-Bold.ttf"],
    "font_size_range": [40, 60],
    "char_color_range": {"r": [0, 80], "g": [0, 80], "b": [0, 80]},
    "rotation_range_deg": [-25, 25],
    "char_spacing_range": [-5, 5]
  }
}