docs: public boolean lookupFernPN( TldRegionFernInfo info ) {
  
  		ImageRectangle r = info.r;
  
  		float rectWidth = r.getWidth();
  		float rectHeight = r.getHeight();
  
  		float c_x = r.x0+(rectWidth-1)/2.0f;
  		float c_y = r.y0+(rectHeight-1)/2.0f;
  
  		int sumP = 0;
  		int sumN = 0;
  
  		for( int i = 0; i < ferns.length; i++ ) {
  			TldFernDescription fern = ferns[i];
  
  			int value = computeFernValue(c_x, c_y, rectWidth, rectHeight, fern);
  
  			TldFernFeature f = managers[i].table[value];
  			if( f != null ) {
  				sumP += f.numP;
  				sumN += f.numN;
  			}
  		}
  
  		info.sumP = sumP;
  		info.sumN = sumN;
  
  		return sumN != 0 || sumP != 0;
  	}