As with anything in image machine learning, it's all about the complexity of your feature space and how well it captures your business needs. Starting with near

As with anything in image machine learning, it's all about the complexity of your feature space and how well it captures your business needs. Starting with nearest-neighbors with color-based features is a great starting point, and it's always great to see posts that start from scratch and show how far you can get. For those interested in some of the commercial solutions in the space, Cortexica ( http://www.cortexica.com/ http://www.cortexica.com/ ) is doing interesting work using neural networks for fashion image similarity. Sadly, they seem to be focusing on white-label solutions rather than having an API.