Tatt-C was conducted as an "open-book" test, where participants were provided with the dataset and ground-truth data, ran their algorithm(s) on the data following a specified protocol on their own hardware, and provided their system output to NIST for uniform scoring and analysis. Accuracy was measured for the five Tatt-C use cases, including the impact of gallery size for certain scenarios. Detailed descriptions and image examples of the use cases can be found in Section 2.2 of this report. Key Results Key results for the five use cases studied are: • Tattoo Identification evaluated matching different instances of the same tattoo image from the same subject over time. On a gallery size of 4 375, the top performing algorithm (MorphoTrak) reported a rank 10 hit rate ⇤ of 99.4% and mean average precision (MAP) ⇤ of 99.4%. Section 3.1 • Region of Interest evaluated matching a subregion of interest that is contained in a larger image canvas. On a gallery size of 4 363, the top performing algorithm (MorphoTrak) reported a rank 10 hit rate of 97% and MAP of 95.4%. Section 3.2 • Mixed Media evaluated matching visually similar or related tattoos using different types of non-tattoo imagery (i.e. sketches, scanned print, computer graphics, and graffiti). On a gallery size of 55, the top performing algorithm (MITRE) reported a rank 10 hit rate of 36.5% and MAP of 15.1%. Section 3.3 • Tattoo Similarity evaluated matching visually similar or related tattoos from different subjects. On a gallery size of 272, the top performing algorithm (MITRE) achieves a rank 10 accuracy of 14.9% and MAP of 5.2%. Section 3.4 • Tattoo Detection evaluated detecting whether an image contains a tattoo or not. On a mixed dataset of 1 349 tattoo images and 1 000 face images, the top performing algorithm (MorphoTrak) reported an overall detection accuracy ⇤ of 96.3%. Section 3.5 Factors that influenced accuracy included: • Algorithms: Tattoo detection and matching accuracy depends strongly on the implementation of the core technology as algorithm performance varied substantially. Sections 3.1, 3.2, 3.3, 3.4, and 3.5 ⇤ For the definition of hit rate, MAP, and overall detection accuracy, see Section 2.3. Generally speaking, the higher the hit rate, MAP, and detection accuracy value, the more accurate the algorithm. Finally, the authors are grateful to Amanda Noxon (Michigan State Police), Dr. Jim Matey (NIST), and Mike Garris (NIST) for their thorough and constructive review of this document. Release Notes. Versioning: This document is Revision 1.0 of the original report, which was originally published in September 2015.. Typesetting: Virtually all of the tabulated content in this report was produced automatically. This involved the use of scripting tools to generate directly type-settable L A T E X content. This improves timeliness, flexibility, maintainability, and reduces transcription errors.. Graphics: Many of the figures in this report were produced using Hadley Wickham's ggplot2 [29] package run ning under , the capabilities of which extend bey...