protected void checkSignature(byte[] buf){
  if (!Arrays.equals(buf,PngHelperInternal.getPngIdSignature()))   throw new PngjInputException("Bad PNG signature");
}

protected void checkSignature ( byte [ ] buf ) { if ( ! Arrays . equals ( buf , PngHelperInternal . getPngIdSignature ( ) ) ) throw new PngjInputException ( "Bad PNG signature" ) ; }
throws pngjinputexception if bad signature
