[OPTICAL REVIEW Vol. 19, No. 3 (2012) 142-149]
© 2012 The Japan Society of Applied Physics

Fidelity Evaluation of Metallic Luster in Six-Band High-Dynamic-Range Imaging

Yuri MURAKAMI*, Jin NOMURA1, Manabu OHYAMA1, and Masahiro YAMAGUCHI2

Imaging Science and Engineering Laboratory, Tokyo Institute of Technology, Yokohama 226-8503, Japan 1Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, Yokohama 226-8503, Japan 2Global Scientific Information and Computing Center, Tokyo Institute of Technology, Meguro, Tokyo 152-8550, Japan

(Received January 27, 2012; Accepted February 22, 2012)

This paper presents subjective evaluation results for images reproducing metallic luster. The images were produced by a six-band high-dynamic-range imaging technique, which provides high color fidelity and the capability of various tone mapping operations. The preferences for images produced by four kinds of tone mapping operations were evaluated by means of a paired comparison method under the conditions that observers could or could not refer to real scenes. The evaluation results indicated that preferences for images depend on tone mapping operations, especially for objects that have the luster changing over a large area with moderately high intensity. In addition, when referring to a real scene, the spatially varying tone compression, which reproduces the color and complex characteristics of metallic luster, was significantly preferable to the tone mappings by other approaches. Without a real scene, the preference was also strong for images produced by simply saturating pixel values at highlights.

Key words: image reproduction, metallic luster, high dynamic range imaging, multiband imaging, tone mapping, subjective evaluation

*E-mail address: yuri@isl.titech.ac.jp