High-dynamic-range visualization of density plots

Abstract

Density maps are an important means of data representation and have been widely used in various visualizations, e.g., scatter plots, parallel coordinates, and trajectories. Typically, density maps have high dynamic-ranges which are beyond the displayable intensities on a monitor. The common operators to map the data values to displayable intensities (for example, linear, logarithmic, and gamma mappings) do not work in all situations and produce unsatisfactory results, where features may be lost or misleading visualizations may be created. Therefore, we propose a perceptual-based model to better visualize high-dynamic-range density maps: we map high-dynamic-range data to a displayable range through a perceptual tone mapping operator; on top of that, we apply glare simulation to highlight high-density regions which are found by our automatic bright pixel detector. The glare is used to highlight high-density regions, while the tone mapping preserves structural details. In addition, we evaluate different tone mapping operators on density maps in typical data visualizations, which has not been studied to the best of our knowledge. For the whole approach, an efficient GPU-based implementation and an easy-to-use application with intuitive user interactions are provided. We demonstrate the effectiveness of our method through a wide range of density map visualizations.