Gregory S. Pettitt

DLP Cinema projection: A hybrid frame-rate technique for flicker-free performance

Film is recorded at 24 Hz, which is sufficient to achieve the effect of motion but is well within the flicker sensitivity of the human-visual system (HVS) and thus would result in severe flicker. To avoid this, film projectors project at twice this rate, using a 48-Hz screen refresh rate. While this greatly mitigates flicker, projected film images still exhibit considerable flicker in bright scenes. DLP Cinema projection technology allows us to display images at any frame rate, and in practice we have been able to match the 48-Hz refresh rate of film projectors. This paper describes a technique by which we take advantage of the fact that the HVS temporal sensitivity curve shows more sensitivity with bright content but much less sensitivity as content dims. This is done using the control versatility of the Digital Micromirror Device (DMD), which allows independent control of every bit. The result is an overall image signal that is beyond the HVS temporal sensitivity curve, resulting in the complete removal of any visible flicker. This technique gives DLP Cinema projection its characteristic solid and stable appearance that standard film projection does not provide.

21.4: DLP Cinema™ Projectors: Enabling Digital Cinema

Digital Light Processing™ projection displays span the gamut of applications from ultralight to ultrabright. DLP Cinema™ projection displays are the adaptation of conventional DLP™ projectors to meet the requirements of digital cinema. This paper describes DLP Cinema™ prototype projectors and ongoing field demonstrations of these prototypes in eighteen or more theater locations in North America, Europe and Japan.