2^16 shades of gray: high bit-depth projection using light intensity control

Abstract

Projectors create grayscale images by outputting a series of bitplanes or binary images within a short time period. While this technique works well for projecting low bit-depth (8-bit) images, it becomes infeasible for high bit-depth (say, 16-bit) projection - a capability that is increasingly desirable in many applications including cinemas and gaming. Existing designs for high bit-depth projection rely on multiple spatial light modulators and, as a consequence, their costs and complexities are usually far beyond the average consumer. In this paper, we describe a technique for high bit-depth projection using a single light modulator by adopting intensity-modulated light sources. With the proposed light intensity modulation, we show that the number of bitplanes required to achieve a desired bit-depth can be dramatically reduced - by marginally trading-off the brightness of the projected image. Hence, given a spatial light modulator of a fixed bandwidth for projecting bitplanes, the proposed projector design can achieve higher bit-depth as well as expanded color gamut while achieving the same video framerate as conventional projectors. The proposed design involves a minor modification to traditional projector designs, namely intensity modulation of the light sources, and hence, can be adopted widely by both traditional low bit-depth projectors and modern high dynamic-range projectors. Finally, we present a hardware prototype to showcase and validate the performance of the proposed design.