code: public static GrayF32 convolveBorder(GrayF32 integral ,
  										 IntegralKernel kernel ,
  										 GrayF32 output , int borderX , int borderY )
  	{
  		output = InputSanityCheck.checkDeclare(integral,output);
  
  		if(BoofConcurrency.USE_CONCURRENT) {
  			ImplIntegralImageConvolve_MT.convolveBorder(integral, kernel, output, borderX, borderY);
  		} else {
  			ImplIntegralImageConvolve.convolveBorder(integral, kernel, output, borderX, borderY);
  		}
  
  		return output;
  	}
docs: Convolves the kernel only across the image's border.
  
  @param integral Integral image. Not modified.
  @param kernel Convolution kernel.
  @param output The convolved image. If null a new image will be created. Modified.
  @param borderX Size of the image border along the horizontal axis.
  @param borderY size of the image border along the vertical axis.