def __call__(self, pred, true):
    bgr_mask = (true == 0)
    return ((pred[bgr_mask] - true[bgr_mask]).abs_().mean() * 1000.0)
def __call__(self, pred, true):
    bgr_mask = (true == 0)
    return ((pred[bgr_mask] - true[bgr_mask]).abs_().mean() * 1000.0)