code: public static <T extends ImageBase<T>>
  	PyramidDiscrete<T> discreteGaussian( int[] scaleFactors , double sigma , int radius ,
  										 boolean saveOriginalReference, ImageType<T> imageType )
  	{
  		Class<Kernel1D> kernelType = FactoryKernel.getKernelType(imageType.getDataType(),1);
  
  		Kernel1D kernel = FactoryKernelGaussian.gaussian(kernelType,sigma,radius);
  
  		return new PyramidDiscreteSampleBlur<>(kernel, sigma, imageType, saveOriginalReference, scaleFactors);
  	}
docs: Creates an updater for discrete pyramids where a Gaussian is convolved across the input
  prior to sub-sampling.
  
  @param imageType Type of input image.
  @param sigma Gaussian sigma.  If < 0 then a sigma is selected using the radius.  Try -1.
  @param radius Radius of the Gaussian kernel.  If < 0 then the radius is selected using sigma. Try 2.
  @return PyramidDiscrete