Luminance contrast analyses for low vision in a senior living facility: A proposal for an HDR image-based analysis tool Elif Tural a, * , Mehmedalp Tural b a School of Design and Human Environment, Oregon State University, 328 Milam Hall, 97331 Corvallis, OR, USA b Corvallis, OR, USA article info Article history: Received 19 February 2014 Received in revised form 16 April 2014 Accepted 7 June 2014 Available online 16 June 2014 Keywords: Lighting for seniors HDR photography Luminance contrast Design for low vision abstract This study proposes the use of digital photography as a visual assessment tool to incorporate the needs of the aging eye to the design process. The research utilizes digital photographs to collect luminance and luminance contrast data, and employs visual field masks to represent and analyze human's visual field. Digital image blurring filters are developed to examine contrast perception problems related to visual acuity (specifically, recognition acuity) loss. Employing an experimental design for tool testing and involving a case study of a senior living facility for empirical data collection, the proposed research aims to verify using a digital image-based analysis tool to represent the visual acuity levels of the aging eye, and explore luminance distribution and luminance contrast ratios that cause mobility problems and affect the safe orientation of people with low visual acuity. The results of the case study demonstrated the viability of the proposed tool, highlighting reduced luminance contrast on the egress staircase for lower visual acuity conditions. The outcomes include lighting design caveats with respect to preventing injuries and falls, and facilitating accessibility and comfort in senior living environments. Future research can benefit from the proposed methodology to study both qualitative and quantitative aspects of the luminous environment in different indoor and outdoor contexts. The proposed method and analysis of luminance contrast values will help revisit the viability of the existing lighting guidelines and develop perceptual lighting metrics that take into account the lighting-related needs and preferences of senior populations. Published by Elsevier Ltd. 1. Introduction Prevalence of visual impairment increases with age and may affect an individual's visual performance. Survey findings show that 17% of the Americans between the ages of 65e74 and 26% of the Americans older than 75 years report some form of visual impair- ment [1]. Studies at nursing homes also indicate that vision loss is a problem especially for residents that are 65 and older: 27% of the residents stated having particular visual impairment. It is plausible to say that real numbers might be higher since most impairment tests involve “verbal or quasi verbal” responses which can be affected by aging or the tendency of the individual to accept “gradual failure of sight”, hindering actual conditions [2,p.169; 3, p.4]. The decline in visual functions may negatively affect the per- formance of dailydespecially vision-relateddtasks such as reading and writing, may restrict orientation and mobility, and cause behavioral problems [3]. By 2030, 20% of the population in United States will be 65 or older [4,5] and vision related problems will be more pronounced. Although literature on aging visual system and age-related eye diseases are detailed and well-defined [6,7], and research on re- lationships between lighting levels and visual functions in ophthalmology is vast; translations to architecture and environ- mental design are mostly limited to illuminance-related guidelines. Visual perception-based assessment tools are necessary to explore how one interacts with the environment and to assess the visual conditions of current settings. Use of such tools are particularly important in residential and public buildings for the betterment of luminous environment to counteract problems pertaining to differing visual impairments. Reflecting on those requirements, this study proposes the use of digital photography as a visual assessment tool to incorporate the needs of the aging eye to the design process. This research utilizes digital photographs to collect luminance and luminance contrast data, and employs visual field masks to represent and analyze * Corresponding author. Tel.: þ1 5417370992; fax: þ1 5417370993. E-mail addresses: elif.tural@oregonstate.edu (E. Tural), mtural@asu.edu (M. Tural). Contents lists available at ScienceDirect Building and Environment journal homepage: www.elsevier.com/locate/buildenv http://dx.doi.org/10.1016/j.buildenv.2014.06.005 0360-1323/Published by Elsevier Ltd. Building and Environment 81 (2014) 20e28