code: protected void subpixelPeak(int peakX, int peakY) {
  		// this function for r was determined empirically by using work regions of 32,64,128
  		int r = Math.min(2,response.width/25);
  		if( r < 0 )
  			return;
  
  		localPeak.setSearchRadius(r);
  		localPeak.search(peakX,peakY);
  
  		offX = localPeak.getPeakX() - peakX;
  		offY = localPeak.getPeakY() - peakY;
  	}
docs: Refine the local-peak using a search algorithm for sub-pixel accuracy.