The quick diffusion of forged images throughout Social Media and Internet are becoming a big problem due to the influence they have on people's thoughts and stances on things. In this respect, since JPEG is one of the most popular image formats on the Web thanks to its high relation quality-weight; throughout the years some investigators have proposed different methods which have allowed us to track the traces left by the compression processes in order to determine the authenticity of these kind of images. In particular, the model based on the A-Contrario aprroach involves a performance of 75% and 42% in the distinction between original and fake parts, respectively; showing that, under some conditions, it would be a good first step in the forensic identification of images.