So I guess my question is where is the juice being squeezed from, why does the vision token representation end up being more efficient than text tokens.
This sort of "dynamic chunking" of low-level information, perhaps down to the level of raw bytes, into shorter sequences of meta tokens for input to some big sequence processing model is an active area of research. Eg, one neat paper exploring this direction is: "Dynamic Chunking for End-to-End Hierarchical Sequence Modeling" [1], from one of the main guys behind Mamba and other major advances in state-space models.
"I'm studying at Oxford Univ" has basically no loss in meaning even though "University" was truncated to less than half its characters.
Lots of words have multiple meanings and can mean different things even if used in the same sentence/context just from the interpretation of the person reading it.
Heck, it'd argue that most (not all) dayjob conflicts are down to such differences in interpretation /miscommunications
The number of bits to represent a text or vision token is the same, since they are both represented as embeddings of a fixed number of dimensions defined by the Transformer (maybe a few thousand for a large SOTA model).
Whether a vision token actually contains enough information to accurately extract (OCR) all the text data from that portion of the image is going to depend on how many pixels that vision token represents and how many words were present in that area of the image. It's just like considering images of the same page of text at different resolutions - a 1024x1024 image vs a 64x64 one, etc. As the resolution decreases so will OCR accuracy. At some point the resolution is insufficient and the words become a blurry mess and OCR accuracy suffers.
This is what DeepSeek are reporting - OCR accuracy if you try to use a single vision token to represent, say, 10 text tokens, vs 20 text tokens. The vision token may have enough resolution to represent 10 tokens well, but not enough for 20.
It will never be as precise as textual tokens but it can be really good as they show in the paper.
Each vision token represents a 16x16 patch, but to fully cover a word you might need multiple vision tokens. So assuming that the embedding size of the vision token and text token is the same `d` (which I think has to be the case for multimodal models), then wouldn't the fair comparison be `x * d` elements for a sentence in terms of vision tokens, and `y * d` for the same sentence in terms of text tokens? I don't see how you could see a priori that x << y (especially by a factor of 10 as quoted in the paper).
That said, if I do experimentally try this by shrinking this very comment down to the smallest font size I can read it at, then seeing how many 16x16 tokens it takes, you can fit more text than I expected in each "vision token". So I can maybe buy that x is at least not greater than y. But it can't be as simple as "each vision token can cover more text", since that only enables better compression if the encoder can actually uncover some sort of redundancy within each token. (And presumably the type of redundancy it uncovers probably isn't something that "classical" compression techniques can exploit, otherwise it seems like it would have been tried by now?).
But I think it's still experimentall.