Classic compression problem. There is no free lunch in that you'd still need to compute the 'difference', which is a combinatorial search. If you could indeed c

Classic compression problem. There is no free lunch in that you'd still need to compute the 'difference', which is a combinatorial search. If you could indeed compute the difference, technically you would throw away the raw data and store only differences. But you'd still need to temporarily have access to the raw data.