In this study, we propose color images with color enhancement for congenital red-green color deficiency on the basis of the model proposed by Mochizuki et al. [In Terrassa, Spain: Proceedings for CGIV, Springfield VA: IS&T 2008;208-213] with the aim of facilitating color customization in displays used by color-deficient observers. Three types of color enhancements for deficiency were addressed in this study: colors were enhanced along the protan confusion line (i.e., P-enhancement), deutan confusion line (i.e., D-enhancement), and a line between the protan and deutan confusion lines (i.e., mix-enhancement). We investigated the color-enhanced image that is most preferred by each group of protan, deutan, and normal observers. Protan and deutan in this study indicate observers that are both dichromats and anomalous trichromats. Nine protan, nine deutan, and six normal observers participated in the experiment. The results showed that among the three types of color enhancements, the D-enhancement provided the best performance for protan observers. For deutan observers, all three types provided effective enhancement, although the P- and mix-enhancements were slightly better than the D-enhancement. Our results indicated that color enhancement increases the preference evaluations of protan and deutan observers. (c) 2013 Wiley Periodicals, Inc. Col Res Appl, 39, 234-251, 2014; Published Online 20 February 2013 in Wiley Online Library (). DOI 10.1002/col.21795