code: private static boolean isBmpHeader(final byte[] imageHeaderBytes, final int headerSize) {
      if (headerSize < BMP_HEADER.length) {
        return false;
      }
      return ImageFormatCheckerUtils.startsWithPattern(imageHeaderBytes, BMP_HEADER);
    }
docs: Checks if first headerSize bytes of imageHeaderBytes constitute a valid header for a bmp image.
  Details on BMP header can be found <a href="http://www.onicos.com/staff/iz/formats/bmp.html">
  </a>
  @param imageHeaderBytes
  @param headerSize
  @return true if imageHeaderBytes is a valid header for a bmp image