The FootScanAge is a non-invasive, more accurate novel approach to automatically estimate the gestational age of newborns. This task is performed by the computational analysis of the features from the newborn plantar surface. The FootScanAge system is composed by two main tools: (1) image processing and (2) data mining. In this paper, we present the image processing tool that extract features of the plantar surface by applying image processing techniques developed to work on the footprint of the newborns, which present some singular characteristics. We included the results that support the determination of an adequate gestational age score by using the data mining tool.