def __call__(self, X, alpha=None, bytes=False):
    """
    *X* is either a scalar or an array (of any dimension).
    If scalar, a tuple of rgba values is returned, otherwise
    an array with the new shape = oldshape+(4,). If the X-values
    are integers, then they are used as indices into the array.
    If they are floating point, then they must be in the
    interval (0.0, 1.0).
    Alpha must be a scalar between 0 and 1, or None.
    If bytes is False, the rgba values will be floats on a
    0-1 scale; if True, they will be uint8, 0-255.
    """
Converting a grayscale image to an RGB heatmap image with matplotlib