Hue Preservation using Enhanced Integrated Multi-scale Retinex for Improved Color Correction

Abstract

The images captured by most current digital cameras suffer from a narrow dynamic range that results in poor color fidelity and perceived image quality. Accordingly, this article proposes an enhanced integrated multi-scale Retinex (IMSR) method in a device-independent color space, namely, CIELAB, to preserve the hue and obtain a high contrast and naturalness. To achieve the desired objectives, a captured sRGB image is transformed into CIELAB color space using standard equations, then the IMSR is applied to only the L values, thereby preserving the balance of the color components, hue, and saturation. However, since this process causes unnatural undersaturation, a saturation adjustment is per- formed by applying a simple saturation compensation method, which maintains the chromatic ratio with respect to the sRGB gamut boundary according to the variation in the luminance. The adjusted CIELAB values are then transformed into sRGB using an inverse transform function. In experiments, the proposed method showed an improved visibility in both dark and bright regions, while reducing color distortion. Furthermore, in an observation preference test, the images resulting from the proposed method were perceived as hav- ing a higher visibility and naturalness. © 2011 Society for Imaging Science and Technology. DOI: 10.2352/J.ImagingSci.Technol.2011.55.1.010504