We implemented a pretty amazing 2019 paper for image similarity / image retrieval using fast.ai. It’s of much lower complexity than other state-of-the-art methods (e.g. no triplet mining required), as fast to train as regular image classification DNNs, and has results which are on-par or better than the best previous published results.
Repository: https://github.com/microsoft/computervision-recipes/tree/master/scenarios/similarity