Digital image enhancement for recording rupestrian engravings: applications to an alpine rockshelter

Image processing software, such as the DStretch plug-in for ImageJ or Photoshop, are currently used to make faint rupestrian pictographs more legible. During the ongoing study of an Alpine rockshelter, these software proved to be equally useful for the visualization of linear engravings and scratchings. This unexpected function of DStretch, created for the study of rupestrian paintings, made it possible to clarify and correct the previous recordings of an incised Iron Age warrior and to facilitate the digital tracing of a modern maritime scene. Even if such convincing results are determined by particular local geological conditions in this case, this function could facilitate the study of engravings in other contexts where the lithology of smooth rock surfaces produces a sharp contrast with incised images.