docs: public boolean computeLaplaceSign(int x, int y, double scale) {
  		int s = (int)Math.ceil(scale);
  		kerXX = DerivativeIntegralImage.kernelDerivXX(9*s,kerXX);
  		kerYY = DerivativeIntegralImage.kernelDerivYY(9*s,kerYY);
  		double lap = GIntegralImageOps.convolveSparse(ii,kerXX,x,y);
  		lap += GIntegralImageOps.convolveSparse(ii,kerYY,x,y);
  
  		return lap > 0;
  	}