HD-RACE: Spray-based Local Tone Mapping Operator

Abstract

In this paper, a local tone mapping operator is proposed. It is based on the theory of sprays introduced in the Random Sprays Retinex algorithm, a white balance algorithm dealing with the locality of color perception. This tone mapping implementation compresses high dynamic range images by using three types of computations on sprays. These operations are carefully chosen so that the result of their convex combination is a low dynamic image with a high level of detail in all its parts regardless of the original luminance values that may span over large dynamic ranges. Furthermore, a simple local formulation of the Naka-Rushton equation based on random sprays is given. The experimental results are presented and discussed.Index Terms-High dynamic range images, tone mapping, Naka-Rushton equation, Retinex This work was supported by the Croatian Science Foundation under Grant DOK-01-2018. own preference. Additionally, a local formulation of the Naka-Rushton equation based on sprays is proposed. This ensures that all TM calculations of the proposed TMO are entirely performed on local regions represented as sprays.

Natureness‐preserving tone mapping operator based on improved guided filter and adaptive Gamma curve

“…Tone mapping operators usually result in colour shifts, which generally manifest as oversaturation or undersaturation, and therefore it is necessary to add a colour correction step to ensure that the colour appearance is maintained after dynamic range compression. Nowadays, a number of methods have been proposed for colour correction, such as iCAM06‐based method [19], fixed exponent based method [30] and spray‐based method in recent years [31].…”