---
license: other
license_name: apache-2.0-and-cc-by-nc-sa-4.0
license_link: LICENSE
base_model:
  - numind/NuExtract3
tags:
  - nnef
  - tract
  - document-understanding
  - vision-language
  - layout-analysis
library_name: tract
---

# einkpub — model weights for `einkpdf`

NNEF exports of the two models [`einkpdf`](https://github.com/epi/einkpdf) uses to
turn research PDFs into EPUBs sized for a 7" e-ink reader. Both run under
[tract](https://github.com/sonos/tract) on CPU — no GPU, and no Python at
inference time.

A page is rasterized, the **layout** model finds the labelled regions and their
reading order, and the **transcriber** turns the page into structured markdown.
The layout half exists because the transcriber emits no coordinates at all, so
there would otherwise be nothing to crop a figure from.

## ⚠️ This repository holds two models under two different licences

HuggingFace has one licence field per repository, so this one is tagged `other`.
**The licence depends on which files you use.**

| Path | Model | Licence |
|---|---|---|
| `/` | NuExtract3 transcriber | **Apache-2.0** — see `LICENSE`, `NOTICE` |
| `/layout` | surya layout predictor | **CC-BY-NC-SA-4.0** — see `layout/LICENSE`, `layout/NOTICE` |

If you take only the transcriber, Apache-2.0 governs and there is no
non-commercial restriction. If you take anything under `layout/`, the
CC-BY-NC-SA-4.0 terms apply to those files, including the non-commercial and
share-alike conditions.

surya's author waives the non-commercial term for organizations under $5M USD in
gross revenue over the most recent 12 months **and** under $5M in lifetime
VC/angel funding, that are not competitive with the
[Datalab API](https://www.datalab.to/). That waiver is theirs to grant, not this
repository's to pass on — commercial licensing is available from Datalab.

## Files

### Transcriber — Apache-2.0

| File | Size | Purpose |
|---|---|---|
| `vision.nnef.tgz` | 1.3 GB | Vision tower |
| `decoder.nnef.tgz` | 2.3 GB | Text decoder |
| `tokenizer.json` | 20 MB | HuggingFace tokenizer |
| `einkpdf.json` | 4 KB | Runtime config consumed by `einkpdf` |

### Layout — CC-BY-NC-SA-4.0

| File | Size | Purpose |
|---|---|---|
| `layout/layout_predictor_encoder.nnef.tgz` | 299 MB | Vision encoder |
| `layout/layout_predictor_decoder_prefill.nnef.tgz` | 219 MB | Decoder, prefill pass |
| `layout/layout_predictor_decoder_iter.nnef.tgz` | 199 MB | Decoder, iterative pass |
| `layout/layout_config.json` | 1 KB | Slicer and preprocessor config |
| `layout/model_config.json` | 6 KB | Decoder token config |

## Changes from the base models

**Transcriber**, from [`numind/NuExtract3`](https://huggingface.co/numind/NuExtract3):

- Converted from safetensors to NNEF for tract.
- Weights at f16; the decoder additionally quantized to Q4_0, cutting peak RSS
  from ~21 GB to ~6 GB and running ~1.76x faster on CPU.
- No fine-tuning.

**Layout**, from [surya](https://github.com/VikParuchuri/surya) (checkpoint
`2025_02_18`):

- Converted from PyTorch to NNEF, split into encoder, decoder-prefill and
  decoder-iterative graphs.
- No fine-tuning.

Neither conversion changes model architecture, and both are intended to match
their originals. The layout preprocessor is checked against golden arrays from
surya's Python implementation.

## A note on operator names

The layout graphs were exported against tract 0.21 and still name
`tract_onnx_is_nan`, which tract 0.23 moved into core as `tract_core_is_nan`.
`einkpdf` re-registers the old name at load time rather than requiring a
re-export; anything else loading these graphs on tract ≥ 0.23 will need to do the
same.