Flickr has received an update that includes the ability for users to search the site based on visual similarity. This should make it easier to find the exact kind of picture you’re looking for.
Any image from Flickr’s search results can be used to find images of similar shape, composition, color, or category. Deep neural networks are used by the site to figure out which images are actually similar.
The tool won’t be perfect right now and there will be cases where images match on little more than color, but that’ll change over time.