Perceptual photometric seamlessness in projection-based tiled displays

Abstract

Arguably, the most vexing problem remaining for multi-projector displays is that of photometric (brightness) seamlessness within and across different projectors. Researchers have strived for <i>strict photometric uniformity</i> that achieves identical response at every pixel of the display. However, this goal typically results in displays with severely compressed dynamic range and poor image quality. In this article, we show that strict photometric uniformity is not a requirement for achieving photometric seamlessness. We introduce a general goal for photometric seamlessness by defining it as an optimization problem, balancing <i>perceptual uniformity</i> with <i>display quality</i>. Based on this goal, we present a new method to achieve <i>perceptually seamless high quality displays</i>. We first derive a model that describes the photometric response of projection-based displays. Then we estimate the model parameters and modify them using perception-driven criteria. Finally, we use the graphics hardware to reproject the image computed using the modified model parameters by manipulating only the projector inputs at interactive rates. Our method has been successfully demonstrated on three different practical display systems at Argonne National Laboratory, made of 2 × 2 array of four projectors, 2 × 3 array of six, projectors, and 3 × 5 array of fifteen projectors. Our approach is efficient, automatic and scalable---requiring only a digital camera and a photometer. To the best of our knowledge, this is the first approach and system that addresses the photometric variation problem from a perceptual stand point and generates truly seamless displays with high dynamic range.