Flickr has been experimenting with many new features over the years. The online photo sharing app introduced the auto tag feature in May 2015. To manage uploaded images, Flickr also has a commenting feature built-in. Photographers can edit their work with an additional editing tool, Aviary. The app has come up with yet another innovation to help their users find the right images in Search Results.

Neural network mapping

The head of Flickr, Xanthe Travlos, explained briefly in a blog post that the new search feature uses "advanced technology" to come up with visually similar photos.

In detail, there is machine learning work behind the mapping of these raw pixels. Using their current neural networks, which were trained to map pixels into a set of tags, the Computer Vision team added an extra step to plot the “feature vector” of an image and compare it with that of other images. Images whose feature vectors are located within the same neighborhood will be considered similar.

Defining 'similarity'

There are many ways an image may be similar to other images and still remain different enough not be identical: similarity in color, texture, and semantic similarity. The purpose of Image Search is different from text-based search. With visual searches, we are aiming for “discovery," not just matching query text with the right set of images.

A software development engineer at Yahoo, Clayton Mellina, said in a blog post, “Ideally, we’d like to be able to capture multiple types of similarity.” The team then decided on a specific notion of similarity called “semantic similarity."

Similarity pivot

To find visually similar images, Flickr has added a three-dot button they call the similarity pivot at the top right of every image.

This similarity pivot navigates a search among the billions of images currently being hosted at Flickr. The button works in a similar way Google Images' “Visually Similar” tab works. You click on it, and results will appear. Despite being fairly active in introducing and improving new features, Flickr’s future is currently unclear. Yahoo, who owns Flickr, has been trimming jobs since last year, and there have been rumors that the image sharing app was in the process of being acquired by another company.