code: @Override
  	public byte[] deflate(PngByteArrayOutputStream inflatedImageData, Integer compressionLevel, boolean concurrent) throws IOException {
  		final List<byte[]> results = (concurrent)
  				? deflateImageDataConcurrently(inflatedImageData, compressionLevel)
  				: deflateImageDataSerially(inflatedImageData, compressionLevel, Deflater.DEFAULT_STRATEGY);
  
  		byte[] result = null;
  		for (int i = 0; i < results.size(); i++) {
  			final byte[] data = results.get(i);
  			if (result == null || (data.length < result.length)) {
  				result = data;
  			}
  		}
  		log.debug("Image bytes=%d", (result == null) ? -1 : result.length);
  
  		return result;
  	}
docs: {@inheritDoc}