public static String imageUrlFromThumbUrl(String thumbUrl, char thumbChar) {
        int char_pos = thumbUrl.lastIndexOf(".");
        if (thumbUrl.charAt(char_pos - 1) == thumbChar) {
            return thumbUrl.substring(0, char_pos - 1) + thumbUrl.substring(char_pos, thumbUrl.length());
        }
        return thumbUrl;
    }