Images of Roman Imperial Denarii: A Curated Data Set for the Evaluation of Computer Vision Algorithms Applied to Ancient Numismatics, and an Overview of Challenges in the Field

Abstract

Automatic ancient Roman coin analysis only recently emerged as a topic of computer science research. Nevertheless, owing to its ever-increasing popularity, the field is already reaching a certain degree of maturity, as witnessed by a substantial publication output in the last decade. At the same time, it is becoming evident that research progress is being limited by a somewhat veering direction of effort and the lack of a coherent framework which facilitates the acquisition and dissemination of robust, repeatable, and rigorous evidence. Thus, in the present article, we seek to address several associated challenges. To start with, (i) we provide a first overview and discussion of different challenges in the field, some of which have been scarcely investigated to date, and others which have hitherto been unrecognized and unaddressed. Secondly, (ii) we introduce the first data set, carefully curated and collected for the purpose of facilitating methodological evaluation of algorithms and, specifically, the effects of coin preservation grades on the performance of automatic methods. Indeed, until now, only one published work at all recognized the need for this kind of analysis, which, to any numismatist, would be a trivially obvious fact. We also discuss a wide range of considerations which had to be taken into account in collecting this corpus, explain our decisions, and describe its content in detail. Briefly, the data set comprises 100 different coin issues, all with multiple examples in Fine, Very Fine, and Extremely Fine conditions, giving a total of over 650 different specimens. These correspond to 44 issuing authorities and span the time period of approximately 300 years (from 27 BC until 244 AD). In summary, the present article should be an invaluable resource to researchers in the field, and we encourage the community to adopt the collected corpus, freely available for research purposes, as a standard evaluation benchmark.

A Siamese Transformer Network for Zero-Shot Ancient Coin Classification

“…The first forays into the territory were made a decade and a half ago by Zaharieva et al [ 5 ]. The research effort in the field has since increased rapidly and dramatically [ 6 , 7 , 9 , 11 , 12 , 13 , 14 , 15 , 16 ], with an evermore varied range of specific tasks being targeted [ 1 , 6 , 17 , 18 ] and of modeling approaches [ 4 , 7 , 9 , 11 , 16 , 19 ].…”

“…The reason lies in the very large number of emergent classes and the difficulty—or rather, impossibility in practice—of obtaining exemplars of but a small fraction of their total number. As noted by Arandjelović and Zachariou [ 1 ], Online Coins of the Roman Empire (OCRE; see accessed on 1 May 2023), a joint project of the American Numismatic Society and the Institute for the Study of the Ancient World at New York University, lists 43,000 published issues, and the true count is likely to be even greater. The only work to date that has tackled this challenge directly is that of Cooper and Arandjelović [ 7 ].…”

“…Different issues of coins are uniquely referred by their identifiers from a variety of standard references, such as the Roman Imperial Coinage (RIC), as illustrated in Figure 1 . A thorough summary of the relevant terminology for the non-specialist can be found in the recent review of computer vision challenges and problems in ancient numismatics by Arandjelović and Zachariou [ 1 ].…”

Riedones3D: a celtic coin dataset for registration and fine-grained clustering

“…According to [AZ20], the challenges of computer vision applied to numismatics are not correctly addressed. Indeed, most of the works of computer vision on numismatics are in a controlled environment and cannot be applied to real-world conditions.…”

“…The problem is also computation- comparisons; for 1000 coins, there are around 500 000 comparisons to do. According to [AZ20], "Die matching is an unexplored challenge in the realm of automated ancient coin analysis." It can be explained by the fact that public datasets of coins labeled by die are too rare.…”