Jimage operators
	n Arithmetic n I+J    Universal plus(Universal) n I-J    Universal minus(Universal) n I‚J   Universal times(Universal) n I„J   Universal divide(Universal) n ½I½Universal abs() n Filtering n Jimage convolve(double[] k) convolve with symmetrical separable kernel. n  public abstract Jimage convolve(double[][] kernel)with non separable kernel