Spatial Nonuniformity of Color Features in Projection Displays: A Quantitative Analysis

Abstract

In this article, the authors investigate and study the color spatial uniformity of projectors. A common assumption in previous works is to consider that only the luminance is varying along the spatial dimensions. The authors show that the chromaticity plays a significant role in the spatial color shift and should not be disregarded depending on the application. The authors base their conclusions on the measurements obtained from three projectors. First, two methods are used to analyze the spatial properties of the projectors, a conventional approach, and a new one that considers three-dimensional gamut differences. The results show that the color gamut difference between two spatial coordinates within the same display can be larger than the difference observed between two projectors. In a second part, the authors focus on the evaluation of assumptions commonly made in projector color characterization. The authors investigate if these assumptions are still valid along the spatial dimensions. Features studied include normalized response curve, chromaticity constancy of primaries, and channel independence. Some features seem to vary noticeably spatially, such as the normalized response curve. Some others appear to be quite invariant, such as the channel independence.