With the recent developments of the GW detectors like LIGO and VIRGO, we shall see the birth of gravitational astronomy. Thus means the synergistic analysis of gravitational radiation, electromagnetic radiation, neutrinos etc. to provide a fundamental means to look at the Universe by taking advantage of all the signals it sends to us. The electromagnetic (EM) follow-up is a joint effort between interferometry detection and optical band astronomy; its main task is the localization of the possible EM counterpart of the gravitational source detected by the interferometers. Unfortunately the current localization ability of the interferometer is rather approximate; the typical positional uncertainty is of the order of tens to hundreds square degrees. For this reason the search for the EM counterpart is particularly challenging. This thesis intends to develop a new type of image analysis able to find a list of a few candidates as EM counterparts by searching them in astronomical images obtained with the VST telescope (ESO Observatory, Paranal mountain, Chile) and imaged for several nights following the gravitational trigger. In this thesis, data analysis and image processing techniques will be exploited as necessary tools for physics. These techniques are very important in the several branches of science and in for real-world applications.