High Brightness HDR Projection Using Dynamic Freeform Lensing

Abstract

Cinema projectors need to compete with home theater displays in terms of image quality. High frame rate and spatial resolution as well as stereoscopic 3D are common features today, but even the most advanced cinema projectors lack in-scene contrast and, more important, high peak luminance, both of which are essential perceptual attributes of images appearing realistic. At the same time, HDR image statistics suggest that the average image intensity in a controlled ambient viewing environment such as the cinema can be as low as 1% for cinematic HDR content and not often higher than 18%, middle gray in photography. Traditional projection systems form images and colors by blocking the source light from a lamp, therefore attenuating between 99% and 82% of light, on average. This inefficient use of light poses significant challenges for achieving higher peak brightness levels.In this work, we propose a new projector architecture built around commercially available components, in which light can be steered to form images. The gain in system efficiency significantly reduces the total cost of ownership of a projector (fewer components and lower operating cost), and at the same time increases peak luminance and improves black level beyond what is practically achievable with incumbent projector technologies. At the heart of this computational display technology is a new projector hardware design using phase modulation in combination with a new optimization algorithm that is capable of on-the-fly computation of freeform lens surfaces.

Mix-and-match holography

“…Illuminated by the designated green incident light, we obtain a high-contrast image at the designated distance (center green closeup), whose quality is visually matched to the synthetic result. Note that the observed speckle is inherent in the use of highly coherent laser illumination, and can be reduced with a number of strategies that are orthogonal to our approach [Damberg et al 2016]. As one would expect, using another wavelength of light that differs from the design wavelength by >100 nm results in a blurred image (right red close-up).…”

“…Instead of a purely refractive approach, Damberg et al [2016; proposed a design that uses a spatial phase modulator but also a geometric optics image formation model to arrive at a piecewise smooth phase profile with high diffraction efficiency. This work can be interpreted as a hybrid between refractive and diffractive designs.…”

“…[Finckh et al 2010;Kiser et al 2013;Papas et al 2011]) as well as energy efficient high dynamic range (HDR) projection [Damberg et al 2016;Hoskinson et al 2010]. The general problem can be stated as designing an optical system that arranges micro-structures, material distributions, or other physical parameters of an optical element to produce a target light distribution under a given illumination condition.…”

Recent Advances in Projection Mapping Algorithms, Hardware and Applications

“…Since each mirror of an AMA independently controls the direction of light, energy from the light source is spatially reallocated onto the DMD used as the second light modulator. The second configuration uses a phase modulator or freeform lensing approach [DBK*14,DBK*15,DGH16]. Here the original light energy is reallocated based on a dynamic goal‐based caustics principle [PJJ*11] that gathers and disperses light using spatially‐varying diffraction patterns.…”

The high dynamic range imaging pipeline : Tone-mapping, distribution, and single-exposure reconstruction

“…However, the peak brightness is still limited. In more recent work, Damberg et al presented a light steering projection system [58], which can steer light away from dark to bright image areas. This means that although the brightness of a full white image is still limited, when the image only contains smaller highlights these can be boosted to a large extent.…”