'Get poster image url from TVDB'

@staticmethod
def get_image_url(indexer_id):

    image_url = None
    try:
        lINDEXER_API_PARMS = sickbeard.indexerApi(INDEXER_TVDB).api_params.copy()
        lINDEXER_API_PARMS[u'banners'] = True
        t = sickbeard.indexerApi(INDEXER_TVDB).indexer(**lINDEXER_API_PARMS)
        indexer_show_obj = t[int(indexer_id)]
    except (sickbeard.indexer_error, IOError) as e:
        logger.log((((((u'Show    id    ' + indexer_id) + u'    not    found    on    ') + sickbeard.indexerApi(INDEXER_TVDB).name) + u',    not    downloading    poster:    ') + ex(e)), logger.DEBUG)
        return None
    if getattr(indexer_show_obj, u'poster', None):
        image_url = indexer_show_obj[u'poster'].replace(u'posters', u'_cache/posters')
    return image_url
