Canonical Color as a Lens into Concept Decodability in Vision Encoders and VLMs
Probing study shows vision encoders make canonical color linearly decodable from grayscale images and tie it to object identity.
Researchers use canonical color as a controlled testbed for measuring conceptual (not just visible) information in vision encoder representations. A dataset of objects with canonical colors was built, and probes on both color and grayscale images show canonical color remains decodable even when color is removed from the input, linked to predicted object identity. Extending to full VLMs, they find post-training has a surprisingly large effect on color decodability in the vision encoder.