A lighting system 100 and a method of controlling a lighting system are provided. The lighting system comprises a lighting arrangement 106 with a first light emitter 108, a second light emitter 114 and a driving circuitry 104 and comprises a controller 102 providing a control signal 103 to the driving circuitry. The first and second light emitters emit different colors or light L1, L2. The controller is configured to generate the control signal such that a required minimum amount of light is received at a relative position P with respect to the lighting arrangement and that the amount of power used by the lighting arrangement is minimized when the lighting arrangement emits light in accordance with the generated control signal. In the generation of the control signal efficiency ratios R1, R2 for the different light emitters are taken in to account.