def grab_color(ims, color=None):
    """ Grab R,G,or B from RGB image or return original if None """
    if color == "red":
        t_ims = ims[..., 0]
    elif color == "green":
        t_ims = ims[..., 1]
    elif color == "blue":
        t_ims = ims[..., 2]
    else:
        t_ims = ims
    return t_ims