1. A method, for making a lighting system comprising:providing first and second groups of light-emitter diodes (LEDs) on a substrate, each group having one or more LEDs;
providing connections for feeding electric current to each of first and second groups of LEDs on the substrate;
providing a memory device containing at least information associating a plurality of output light colors with a corresponding plurality of combinations of electrical current values, each combination specifying a first electric current for one of the first group of LEDs and a second electric current for one of the second group of LEDs; and
providing a circuit for accessing to the information in the memory device;
disposing the substrate with the first and second groups of LEDs, the memory device, and the circuit on a same circuit board.