Light & Engineering Vol. 23, No. 4, pp. 6-14, 2015 Svetotekhnika No. 5, 2015, pp. 12-18 VISION EXPERIMENT ON CHROMA SATURATION FOR COLOUR QUALITY PREFERENCE* Yoshi Ohno1, Mira Fein2, and Cameron Miller1 1 National Institute of Standards and Technology, Gaithersburg, MD USA, 2 Psychology Department, Oberlin College, Oberlin, Ohio, USA E-mail: ohno@nist.gov ABSTRACT Colour Rendering Index (CRI) often does not correlate well with visual evaluation of colour rendering of light sources at real illuminated scenes. <...> The main reason is that CRI measures colour fi delity, while general users judge colour rendering based on their preference of object colour appearance, thus there is a need for a colour- preference based metric. <...> To obtain data for such colour preference evaluation, a series of vision experiments have been conducted using the NIST Spectrally Tunable Lighting Facility simulating an interior room, where 20 subjects viewed various fruits, vegetables, and 1 * On basis of report published in Proceedings of the 28th CIE Session, 2015, Manchester their skin tones, under illumination of varied saturation levels at correlated colour temperatures (CCT) of 2700 K, 3500 K, and 5000 K. The results of the experiment show that subjects’ preference is consistently peaked at saturation level of ∆C*ab ≈ 5 at all CCT conditions and for all target objects. <...> The results may be useful to develop a colour preference metric. <...> There have been several proposals for alternative metrics [2, 3, 4, 5] but none of them has been Fig. 1. <...> View of the two cubicles of NIST Spectrally Tunable Lighting Facility 6 Light & Engineering adop ted as a standard. <...> The Colour Quality Scale (CQS) developed by NIST [4] has not been accepted as a standard mainly due to a diffi culty defi ning a metric that evaluates combined effects of colour fi delity and colour preference. <...> International Commission on Illumination (CIE) has now two separate TCs, one developing a new colour fi delity metric (TC1–90) and another writing a report <...>