docs: public static <I extends ImageGray<I>, O extends ImageGray<O>>
  	void hessian(O[] derivX, O[] derivY , ImageHessian<O> hessian , O[] derivXX, O[] derivYY , O[] derivXY )
  	{
  		for( int i = 0; i < derivX.length; i++ ) {
  			hessian.process(derivX[i],derivY[i],derivXX[i],derivYY[i],derivXY[i]);
  		}
  	}