Patent ID: 8299722

Claim:
An apparatus comprising: a controller configured to at least adjust brightness of light emitted from a first light emitting diode (LED) and adjust brightness of light emitted from a second LED, wherein, during operation of the controller, the light emitted from the first LED has a different spectrum than the light emitted from the second LED and the controller is further configured to at least: i. receive a first signal indicating a brightness of received light at a first time from both the first and second LEDs; ii. receive a second signal indicating a brightness of the received light at a second time from both the first and second LEDs, wherein a relative contribution to the brightness from the first and second LEDs is different for the first and second times; iii. determine the brightness of light emitted from the first LED and the brightness of light emitted from the second LED using information from the first and second signals; and iv. adjust the brightness of the light emitted from the first LED and the brightness of the light emitted from the second LED in accordance with one or more brightness related target values.