Repeated Look-up Tables.

Efficient hardware implementations routinely approximate mathematical functions with look-up tables, while keeping the error of the approximation under control. For a certain class of commonly occurring 1D functions, namely monotonically increasing or decreasing functions, we found that it is possible to approximate such functions by repeated application of a very low resolution 1D look-up table. There are many advantages to cascading multiple identical LUTs, including the promise of a very simple hardware design and the use of standard linear interpolation. Further, the complexity associated with unequal bin sizes can be avoided. We show that for realistic applications, including gamma correction, high dynamic range encoding and decoding curves, as well as tone mapping and inverse tone mapping applications, multiple cascaded look-up tables can reduce the approximation error by more than 50% compared to a single look-up table with the same total memory footprint.

A Gamut-Mapping Framework for Color-Accurate Reproduction of HDR Images.

Few tone mapping operators (TMOs) take color management into consideration, limiting compression to luminance values only. This could lead to changes in image chroma and hues, which are typically managed with a post-processing step. However, current post-processing techniques for tone reproduction do not explicitly consider the target display gamut. Gamut mapping, on the other hand, deals with mapping images from one color gamut to another, usually smaller, gamut but has traditionally focused on smaller scale, chromatic changes. The authors present a combined gamut- and tone-management framework for color-accurate reproduction of high dynamic range images that can prevent hue and luminance shifts while taking gamut boundaries into consideration. Their approach is conceptually and computationally simple, parameter-free, and compatible with existing TMOs.

Dynamic range reduction inspired by photoreceptor physiology.

A common task in computer graphics is the mapping of digital high dynamic range images to low dynamic range display devices such as monitors and printers. This task is similar to the adaptation processes which occur in the human visual system. Physiological evidence suggests that adaptation already occurs in the photoreceptors, leading to a straightforward model that can be easily adapted for tone reproduction. The result is a fast and practical algorithm for general use with intuitive user parameters that control intensity, contrast, and level of chromatic adaptation, respectively.

A neurophysiology-inspired steady-state color appearance model.

Color appearance models predict how a patch of color is perceived under specific illumination. We derive a new model based on neuroscientific insights, leading to a simpler explanation of color appearance while at the same time predicting existing psychophysical data with similar accuracy for chroma and higher accuracy for lightness and hue.