code: public static IntegralKernel kernelHaarX( int r , IntegralKernel ret) {
  		if( ret == null )
  			ret = new IntegralKernel(2);
  
  		ret.blocks[0].set(-r, -r, 0, r);
  		ret.blocks[1].set(0,-r,r,r);
  		ret.scales[0] = -1;
  		ret.scales[1] = 1;
  
  		return ret;
  	}
docs: Creates a kernel for the Haar wavelet "centered" around the target pixel.
  
  @param r Radius of the box.  width is 2*r
  @return Kernel for a Haar x-axis wavelet.