A new method to define a digital signature of a painting is presented. This signature is composed by a set of patches that are automatically selected as the images regions containing the most relevant information.The region selection is applied on a combination of saliency maps related to different features concerning intensity, color and visual saliency. We present the generation of the feature saliency map exploiting low-level feature representations, and the new algorithm for selecting the most relevant regions. The position and actual size of these regions is not a-priori fixed but is function of the saliency maps, i.e. of the painting content.We present the experimental results on several painting, discussing the trade-offs among image features parameters values and the selected regions.