to apply the approach discussed in this disclosure to a dlp light engine with mechanical iris if the mechanical iris is fast enough that is the light sensor provides light level information to the mechanical iris driver the logic is otherwise the same although the present invention has been described herein with reference to certain kernel configurations and optical devices the devices and processes of the present invention may be applied to many other kernel designs or configurations and may use a wide variety of optical devices in describing preferred embodiments of the present invention illustrated in the drawings specific terminology is employed for the sake of clarity however the present invention is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents which operate in a similar manner for example when describing an iris or variable retarder any other equivalent device or other device having an equivalent function or capability whether or not listed herein may be substituted therewith furthermore the inventors recognize that newly developed technologies not now known may also be substituted for the described parts and still not depart from the scope of the present invention all other described items including but not limited to microdisplays light sources light engines polarizers projection lenses driver boards circuits detectors electronics.