code: public void submitImageDownloadTask(String URL, String id) {
  		Callable<ImageDownloadResult> call = new ImageDownload(URL, id, downloadFolder, saveThumb,
  				saveOriginal, followRedirects);
  		pool.submit(call);
  		numPendingTasks++;
  	}
docs: Submits a new image download task.
  
  @param URL
  The url of the image
  @param id
  The id of the image (used to name the image file after download)