Testing of infrared systems such as FLIRs and missile seekers would be eased by the availability of an infrared scene generator with capability of displaying a complex, dynamic scene, the IR analogy of a motion picture projector. The two main categories of technologies being developed for this purpose are the spatial light modulator and the thermal emitter array. Honeywell is developing a thermal emitter array based on microstructure technology. This paper discusses performance parameters of scene generators such as resolution, radiometric accuracy, and time response. The number of pixels in an array may be an insufficient measure of resolution. Thermal emitters have advantages over light modulators when radiometric accuracy and high contrast are demanded. The unique physical and thermal parameters of the microstructure array technique help alleviate time response problems common to most thermal emitter arrays.