def red_blue_cmap(x):
    """Red to Blue color map

    Args:
        x (float): value between -1 ~ 1, represents normalized saliency score

    Returns (tuple): tuple of 3 float values representing R, G, B.
    """
    if x > 0:
        # Red for positive value
        # x=0 -> 1, 1, 1 (white)
        # x=1 -> 1, 0, 0 (red)
        return 1., 1. - x, 1. - x
    else:
        # Blue for negative value
        x *= -1
        return 1. - x, 1. - x, 1.