private static ImageSaver findImageSaver(String suffix) {
		suffix = suffix.toUpperCase();
		synchronized (suffixTable) {
			ImageSaver saver = suffixTable.get(suffix);
			if (saver == null) {
				try {
					Class<?> imageSaverClass = Class.forName("acm.util." + suffix + "ImageSaver");
					saver = (ImageSaver) imageSaverClass.newInstance();
				} catch (Exception ex) {
					return null;
				}
				suffixTable.put(suffix, saver);
			}
			return saver;
		}
	}