docs: public static <T extends ImageGray<T>>
  	void hessian( T integral, int skip , int size ,
  				  GrayF32 intensity) {
  
  		if( integral instanceof GrayF32) {
  			IntegralImageFeatureIntensity.hessian((GrayF32)integral,skip,size,intensity);
  		} else if( integral instanceof GrayS32) {
  			IntegralImageFeatureIntensity.hessian((GrayS32)integral,skip,size,intensity);
  		} else {
  			throw new IllegalArgumentException("Unsupported input type");
  		}
  	}