PRELIMINARY EVALUATION OF HDR TONE MAPPING OPERATORS FOR CULTURAL HERITAGE

[EN] The ability of High Dynamic Range (HDR) imaging to capture the full range of lighting in a scene has led to an increasing interest in its use for Cultural Heritage (CH) applications. Photogrammetric techniques allow the semi-automatic production of 3D models from a sequence of images. Current photogrammetric methods are not always effective in reconstructing objects under harsh lighting conditions, as significant geometric details may not have been captured accurately in under- and over-exposed regions of the images. HDR imaging offers the possibility to overcome this limitation. In this paper we evaluate four different HDR tone-mapping operators (TMOs) that have been used to convert raw HDR images into a format suitable for state-of-the-art photogrammetric algorithms, and in particular keypoint detection techniques. The evaluation criteria used are the number of keypoints and the number of valid matches achieved. The comparison considers two local and two global TMOs.