def image_to_str(image):
    """
    Converts a docker image into a readable string using the first tag if available otherwise the id.

    :param image: The image to convert to string
    :type image: Image
    :return: A string representation of the given image
    :rtype: str
    """
    tags = image.tags
    if tags:
        return tags[0]
    return str(image.id)
