docs: public static double imageDotProduct(GrayF64 a) {
  
  		double total = 0;
  
  		int N = a.width*a.height;
  		for( int index = 0; index < N; index++ ) {
  			double value = a.data[index];
  			total += value*value;
  		}
  
  		return total;
  	}