Chanprapha PHUANGSUWAN¹, Mitsuo IKEDA¹, and Hiroyuki SHINODA²

¹Color Research Center, Faculty of Mass Communication Technology, Rajamangala University of Technology, Thanyaburi, Pathumthani 12110, Thailand
²Department of Human and Computer Intelligence, College of Information Science and Engineering, Ritsumeikan University, Nojihigashi, Kusatsu, Shiga 525-8577, Japan

(Received September 27, 2013; Revised July 15, 2014; Accepted August 21, 2014)

When we look, under daylight, at a scene in a photograph taken under an incandescent lamp, it appears very reddish, showing that color constancy is not maintained. According to the recognized visual space of illumination (RVSI) concept, color constancy should exist in a photograph if one can perceive three dimensions in it. This prediction was confirmed by applying two viewing techniques to perceive a 3D space in a 2D photograph: a stereoscope viewed with two eyes and a D-up viewer viewed with one eye. A wide range of illumination color was investigated, covering range from vivid blue through to vivid orange, and the color constancy index became larger with the 3D perception than with the 2D perception of the photographs produced by the two techniques.

Key words: color constancy, photograph, illumination, stereoscope, recognized visual space of illumination

^*The experiment with the stereoscope was conducted at Ritsumeikan University during the senior author's 10-month term as a visiting researcher, and the experiment with the D-up viewer was conducted at Chulalongkorn University when she was a PhD student.