On the rankability of visual embeddings
Authors: name: Ankit Sonthalia, name: Arnas Uselis, name: Seong Joon Oh

We study whether visual embedding models capture continuous, ordinal
attributes along linear directions, which we term _rank axes_. We define a
model as _rankable_ for an attribute if projecting embeddings onto such an axis
preserves the attribute's order. Across 7 popular encoders and 9 datasets with
attributes like age, crowd count, head pose, aesthetics, and recency, we find
that many embeddings are inherently rankable. Surprisingly, a small number of
samples, or even just two extreme examples, often suffice to recover meaningful
rank axes, without full-scale supervision. These findings open up new use cases
for image ranking in vector databases and motivate further study into the
structure and learning of rankable embeddings. Our code is available at
https://github.com/aktsonthalia/rankable-vision-embeddings.