def unnormalize(input_img, mean, std):

    """
    :param input_img: (numpy array) Image to be "unnormalized"
    :param mean: (list of mean values) for each channel
    :param std:  (list of std values) for each channel
    :return: (numpy_array) "Unnormalized" image
    """
    return (input_img * std) + mean