Share Email Print

Optical Engineering

Balanced color contrast enhancement for digital images
Author(s): Yanfang Wang; Yupin Luo
Format Member Price Non-Member Price
PDF $20.00 $25.00
cover GOOD NEWS! Your organization subscribes to the SPIE Digital Library. You may be able to download this paper for free. Check Access

Paper Abstract

The balanced enhancement for color images refers to the ability of improving the visual quality of both highlights and dark areas. To this end, a symmetric Naka-Rushton formula (SNRF) is proposed. Particularly, SNRF is symmetric around a pixel-wise threshold which is devised as the adaptive criterion for highlights. Treating RGB channels separately, SNRF regulates each pixel according to the anisotropic local intensity, thus avoiding halos and protecting uniform areas. Further, the color-constancy extension of SNRF (SNRFCC) is presented by incorporating conventional image statistics with the adaptive threshold. Different from traditional color-constancy algorithms that focus on color correction, SNRFCC accomplishes color and lightness adaptation simultaneously. Finally, a postprocessing technique is designed to compensate for the slightly compressed contrast due to the balanced adaptation. Compared with other tone-mapping methods, SNRF achieves more vivid color and details especially in highlights. Besides, comparisons with other color-contrast enhancement algorithms confirm that SNRFCC features the merit of less residual color cast when implementing color constancy on images under varying light.

Paper Details

Date Published: 1 October 2012
PDF: 11 pages
Opt. Eng. 51(10) 107001 doi: 10.1117/1.OE.51.10.107001
Published in: Optical Engineering Volume 51, Issue 10
Show Author Affiliations
Yanfang Wang, Tsinghua Univ. (China)
Yupin Luo, Tsinghua Univ. (China)

© SPIE. Terms of Use
Back to Top