An LED array is controlled by determining a constant relating the peak light output of an LED to the peak driving current of a PWM pulse driving the LED, and multiplying the average current of the PWM pulse by the constant to obtain a value of average light output for the LED. The constant may be determined...http://www.google.ca/patents/US6596977?utm_source=gb-gplus-sharePatent US6596977 - Average light sensing for PWM control of RGB LED based white light luminaries
