“…Applications of hashes, understood as exposed initially, include image retrieval in large databases, authentication and watermarking, among many others. However, in applications of scene recognition, localization or visual loop closing detection, it is accepted that similar or overlapping images are expected to produce similar or close hashes while distinct images produce clearly distinctive hashes (Bonin‐Font, Negre, Burguera, & Oliver, 2014; Jain, Namboodiri, & Pandey, 2017; Shahbazi & Zhang, 2011). According to this definition and in this latter context, an image hash is close or equivalent to the concept of global image descriptor, also used in several pieces of work to identify loop closings (Arandjelovic & Zisserman, 2013; Jégou, Douze, Schmid, & Pérez, 2010; Liu & Zhang, 2012; Negre Carrasco, Bonin‐Font, & Oliver‐Codina, 2016), each one improving its predecessors.…”