PHAROS is an international consortium of fourteen European and North American art historical photo archives committed to creating a digital platform, currently in beta, that allows research among the photographic holdings of all consortium members – an estimated 31 million images, including artworks and supplemental material.
One of the best searching features they’re working on is reverse-image searching – the ability to upload a digital image or URL where an image is located, and search the database as you would a text query to return results related to the image. This image-recognition technology strives to eradicate language barriers inherent in text searching.
via NYTimes; h/t Ann Jensen Adams