code: public static int convolveSparse(GrayS32 integral , IntegralKernel kernel , int x , int y )
  	{
  		return ImplIntegralImageOps.convolveSparse(integral, kernel, x, y);
  	}
docs: Convolves a kernel around a single point in the integral image.
  
  @param integral Input integral image. Not modified.
  @param kernel Convolution kernel.
  @param x Pixel the convolution is performed at.
  @param y Pixel the convolution is performed at.
  @return Value of the convolution