SESYD (Systems Evaluation SYnthetic Documents) is a database of synthetic documents that contains document images with benchmark real information. This database focuses on two major research problems in the field of document image analysis: (1) symbol recognition and localization in online drawing images (such as floor plans and circuit diagrams); (2) character segmentation and recognition in geographic maps. The SESYD database consists of 11 sets for performance evaluation, containing 284k images, 190k symbols and 284k characters. The database was published by Mathieu Delalandre, Ernest Valveny, Tony Pridmore and Dimosthenis Karatzas, and the related paper results are "Generation of Synthetic Documents for Performance Evaluation of Symbol Recognition & Spotting Systems", since its release in 2010, has become a key database in the field of document image analysis and has been cited hundreds of times in research papers.