The European Scanning System is an automatic system for nuclear emulsions used in OPERA to read out emulsion plates. It is an evolution of the SySal system developed to scan nuclear emulsion plates in CHORUS. It integrates several commercial components to obtain a cheap, modular and efficient system that can evolve with technology. All processing steps are demanded to dedicated software, which implies a naturally flexible approach, easy to upgrade. While scanning emulsion images at the speed of 20cm²/h/side, 3D microtracks are reconstructed on-the-fly, with sub-micrometric precision. This is obtained through sophisticated image processing algorithms. Data are continuously sent from microscopes to computing machines in a cluster for higher-level processing such as smart scanning, decision-making to optimize scanning and on-line reconstruction. Information is immediately available in relational shape on an Oracle-based Database system, ready for sharing with other laboratories and analysis sites.