def image_guess_size_from_field_name(field_name):
    """Attempt to guess the image size based on `field_name`.

    If it can't be guessed, return (0, 0) instead.

    :param field_name: the name of a field
    :type field_name: string

    :return: the guessed size
    :rtype: tuple (width, height)
    """
    suffix = '1024' if field_name == 'image' else field_name.split('_')[-1]
    try:
        return (int(suffix), int(suffix))
    except ValueError:
        return (0, 0)