Perceptual images of Conimbriga using High Dynamic Range Alexandrino Gonçalves a, * , João Paulo Moura b, c , Luís Magalhães c, d , Alan Chalmers e a School of Technology and Management, Computer Science and Communication Research Centre, Polytechnic Institute of Leiria, Campus 2, Morro do Lena e Alto do Vieiro, Apartado 4163, 2411-901 Leiria, Portugal b GECAD e Knowledge Engineering and Decision Support Research Center, Porto, Portugal c UTAD e University of Trás-os-Montes e Alto Douro, Quinta de Prados, 5001-801 Vila Real, Portugal d INESC Porto, Portugal e International Digital Laboratory, WMG, University of Warwick, Coventry CV4 7AL, United Kingdom article info Article history: Received 5 August 2011 Received in revised form 10 January 2012 Accepted 2 June 2012 Keywords: Roman illumination Perceptual visualization High Dynamic Range abstract It is widely recognized that new technologies can play an important role in the interpretation of our cultural heritage legacy. This has become a powerful tool providing a better understanding of our past, and thereby, allowing us to attain a glimpse of the environments in which our ancestors lived. In this domain, the way we see such reconstructed environments is particularly important in order to establish an accurate interpretation of that historical setting. However, the desired visual accuracy in the repre- sentation of any archaeological scenario is strictly related to the technology used to visualize it. High Dynamic Range (HDR) technology encompasses the capacity to produce visual results similar to the visual acuity of the human eye, particularly in extreme lighting conditions, such as bright light or dim environments. In this paper we present an ancient flame light simulation method and a perceptual visual user study with HDR images of Roman mosaics and frescoes, illuminated by luminaries of that period, located in one of the most impressive monuments in the ruins of Conimbriga, Portugal. With this work we intend to demonstrate how the use of this particular low intensity Roman light, when compared to other modern illumination, affects the subjects’ perception of ancient artefacts and influences the scenario viewing pattern. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Since the Middle Ages, perhaps even before, the questions related to the historical and cultural past, mainly to the level of archaeological findings, have exerted an enormous and mysterious allure on humans. Ever since then, they have come up with methods and forms to recreate such places, in order to satisfy this recognized natural and ancestral curiosity. However, to accomplish such aspiration, these recreations should be presented to us as they were really perceived by a local inhabitant, respecting the materials and, most importantly, the illumination used back then. On the other hand, the desired visual accuracy in the representation of any archaeological scenario is strictly related to the technology used to visualize it. The Human Visual System (HVS) has a remarkable ability to adjust itself to almost all everyday scenarios. This is particularly evident in extreme lighting conditions, such as bright light or dim environments. However, a major portion of the visible spectra captured by our visual system cannot be represented in most display devices. High Dynamic Range (HDR) imagery is a field of research which is developing techniques to correct such inaccura- cies, ranging from production towards visualization, using real or virtual scenarios. The work presented in this paper intends to employ this new viewing paradigm where it has significant potential; archaeological interpretation, since its high contrast and increased chromaticity can disclose and present us with enhanced viewing experiences (Ruppertsberg et al., 2007). This is particularly evident in our case study where the low intensity flame light method utilised in the period on which this study is based, created a peculiar dim environment where the acuity for all details in the archaeological scenario cannot be attained using today’s common Low Dynamic Range (LDR) technology. The focus of our study is the “House of the Fountains” (Conimbriga, 2012a), in Portuguese Conimbriga ruins. This was a great Roman residential house whose original construction is dated from the beginnings of the first century. Some of the remarkable mosaics, frescoes and fountains are still preserved. * Corresponding author. Tel.: þ351 244820300; fax: þ351 244820310. E-mail addresses: alex@ipleiria.pt (A. Gonçalves), jpmoura@utad.pt (J.P. Moura), lmagalha@utad.pt (L. Magalhães), alan.chalmers@warwick.ac.uk (A. Chalmers). Contents lists available at SciVerse ScienceDirect Journal of Archaeological Science journal homepage: http://www.elsevier.com/locate/jas 0305-4403/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.jas.2012.06.024 Journal of Archaeological Science 40 (2013) 116e128