This paper explores a novel use of Geographic Information Systems and Landscape Metrics in the characterization of lacunae and retouching areas on panel paintings. The aim is to understand some spatial properties of original and non-original areas and contribute to the documentation of conservation and restoration treatments with valuable information. The study uses an orthophoto of the analysed artwork in a GIS program to produce polygons with a direct visual interpretation, corresponding to the major colour zones, the lacunae and the retouching areas. Over these areas landscape metrics are applied and interpreted. The result is a useful set of values describing spatial properties and relations between lacunae, retouching areas and the unaffected zones in the painting. These quantified parameters extend the traditional qualitative diagnosis reports on the state of conservation of artworks and contribute to support the evaluation of conservation and restoration projects.