Retinex Theory for Image Enhancement

Recorded color images differ from direct human viewing by the lack of dynamic range compression and color constancy. Research is summarized which develops the center/surround retinex concept originated by Edwin Land through a single scale design (SSR) to a multi-scale design with color restoration (MSRCR). The MSRCR synthesizes dynamic range compression, color constancy, and color rendition and, thereby, approaches fidelity to direct observation.

A computation for color images that approaches fidelity to scene observation must combine dynamic range compression, color consistency—a computational analog for human vision color constancy—and color and lightness tonal rendition. We refer to the computational analog to human vision color constancy as color consistency. When the dynamic range of a scene exceeds the dynamic range of the recording medium, there is an irrevocable loss of visual information at the extremes of the scene dynamic range.