docs: public static <T extends ImageGray<T>>
  	double convolveSparse( T integral ,
  						   IntegralKernel kernel ,
  						   int x , int y ) {
  		if( integral instanceof GrayF32) {
  			return IntegralImageOps.convolveSparse((GrayF32)integral,kernel,x,y);
  		} else if( integral instanceof GrayF64) {
  			return IntegralImageOps.convolveSparse((GrayF64)integral,kernel,x,y);
  		} else if( integral instanceof GrayS32) {
  			return IntegralImageOps.convolveSparse((GrayS32)integral,kernel,x,y);
  		} else if( integral instanceof GrayS64) {
  			return IntegralImageOps.convolveSparse((GrayS64)integral,kernel,x,y);
  		} else {
  			throw new IllegalArgumentException("Unknown input type");
  		}
  	}