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 colordeficient 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 Denhancement. Our results indicated that color enhancement increases the preference evaluations of protan and deutan observers.

The effects of tone curve and display size on Kansei evaluation of High Dynamic Range (HDR) images were investigated with Japanese and Chinese observers. Forty HDR images (5 tone curves x 4 sizes x 2 contents) were evaluated for Kansei impression using a semantic differential (SD) method with 16 Japanese and 16 Chinese observers with normal color vision. For each adjective, the evaluation value was plotted against the average lightness of the tone curve, and the resulting curves were divided into five types: monotonic increase (MI), monotonic decrease (MD), peak in the upper portion (PU), peak in the lower portion (PL), and flat (F). The results revealed size dependency in evaluations of "Easy to view" and "Difficult to view", which are PU and PL type adjectives, respectively. Size dependency was less prominent in the evaluations of adjectives categorized as MI, MD, and F types, suggesting that the influence of size is related to the effects of the tone curve. A factor analysis examining the evaluation data for both groups of observers extracted three factors for Japanese and two factors for Chinese observers. These results suggest that Kansei evaluation is more multilateral in Japanese observers than in Chinese observers.

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