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A Token-level Text Image Foundation Model for Document Understanding

[📂 Project Pages] [📖 Paper] [🤗 Weights] [🤗 Demo] [🚀 Quick Start]

đź“– Table of Contents

📝 Introduction

We are excited to announce the release of TokenOCR, the first token-level visual foundation model specifically tailored for text-image-related tasks, designed to support a variety of traditional downstream applications. To facilitate the pretraining of TokenOCR, we also devise a high-quality data production pipeline that constructs the first token-level image text dataset, TokenIT, comprising 20 million images and 1.8 billion token-mask pairs. Furthermore, leveraging this foundation with exceptional image-as-text capability, we seamlessly replace previous VFMs with TokenOCR to construct a document-level MLLM, TokenVL, for VQA-based document understanding tasks.

In summary:

(1) The first token-level image text dataset (TokenIT) is proposed;

(2) The first token-level text image foundation model, TokenOCR, is proposed to support downstream tasks.

(3) The image-as-text semantic capability inspires us to develop TokenVL, a VQA-based MLLM tailored for document perception, understanding, and reasoning.

🛠️ Installation

conda create -n tokenocr python=3.9
conda activate tokenocr
pip install -r requirements.txt

Install flash-attn==2.3.6 (optional):

pip install flash-attn==2.3.6 --no-build-isolation

Alternatively you can compile from source:

git clone https://github.com/Dao-AILab/flash-attention.git
cd flash-attention
git checkout v2.3.6
python setup.py install

If you don't use flash-attn, please modify the configs of weights, referring to this

🚀 Quick Start

import os
import torch
from transformers import AutoTokenizer
from internvl.model.internvl_chat import InternVLChatModel
from utils import post_process, generate_similiarity_map, load_image

checkpoint = '/mnt/dolphinfs/hdd_pool/docker/user/hadoop-mt-ocr/guantongkun/VFM_try/processed_models/TokenOCR_4096_English_seg'
image_path = './demo_images/0000000.png'
input_query = '11/12/2020'
out_dir = 'results'

if not os.path.exists(out_dir):
    os.makedirs(out_dir, exist_ok=True)

"""loading model, tokenizer, tok_embeddings """
tokenizer = AutoTokenizer.from_pretrained(checkpoint, trust_remote_code=True, use_fast=False)
model = InternVLChatModel.from_pretrained(checkpoint, low_cpu_mem_usage=True, torch_dtype=torch.bfloat16).eval()
model = model.cuda()

"""loading image """
pixel_values, images, target_aspect_ratio = load_image(image_path)
 

"""loading query texts """
if input_query[0] in '!"#$%&\'()*+,-./0123456789:;<=>?@^_{|}~0123456789':
    input_ids = tokenizer(input_query)['input_ids'][1:]
else:
    input_ids = tokenizer(' '+input_query)['input_ids'][1:]
input_ids = torch.Tensor(input_ids).long().to(model.device)
input_embeds = model.tok_embeddings(input_ids).clone()
all_bpe_strings = [tokenizer.decode(input_id) for input_id in input_ids]


"""Obtaining similarity """
with torch.no_grad():
  vit_embeds, _ = model.forward_tokenocr(pixel_values.to(model.device)) #(vit_batch_size, 16*16, 2048)
  vit_embeds_local, resized_size = post_process(vit_embeds, target_aspect_ratio)
  token_features = vit_embeds_local / vit_embeds_local.norm(dim=-1, keepdim=True)
  input_embedings = input_embeds / input_embeds.norm(dim=-1, keepdim=True)
  similarity = input_embedings @ token_features.t()
  attn_map = similarity.reshape(len(input_embedings), resized_size[0], resized_size[1])

"""generate map locally """
generate_similiarity_map(images, attn_map, all_bpe_strings, out_dir, target_aspect_ratio)


"""user command """
# python quick_start.py

✨ Streamlit Demo

We are excited to present an interactive demo of our project using Streamlit. This demo allows users to explore the capabilities of our model——TokenOCR.

To run the Streamlit demo, you need to wrap the dependencies and then run:
pip install requirement_app.txt
streamlit run app.py --server.port 8400

Features

  • Interactive Interface: Easily upload the image, enter the bpe you want to query, and click the RUN button to view the results of TokenOCR's processing.
  • Real-time Results: Both models, based on internvl and resnet50, give users instant feedback in bpe.
  • User-Friendly: Designed to be intuitive, even for users without a technical background.

How to Use

  1. Access the Demo: [Link to your Streamlit demo]
  2. Upload a Document or Image: Use the interface to upload your files.
  3. Text input: Input your text related to the content of the images.
  4. View Results: See How models generate bpe visualizations in real time.

Then a simple Web-UI to interactive:

image

Feedback

We welcome any feedback or suggestions to improve the demo. Please feel free to reach out via [contact information or GitHub issues].

📺 BPE Token Visualization

Scene|Document|Code

Chart|Table|GUI

Chinese|Punctuation

🏠 Token Family

TokenIT

TokenIT

In the following picture, we provide an overview of the self-constructed token-level TokenIT dataset, comprising 20 million images and 1.8 billion text-mask pairs.

As depicted in Figure 2 (a), each sample in this dataset includes a raw image, a mask image, and a JSON file. The JSON file provides the question-answer pairs and several BPE tokens randomly selected from the answer, along with the ordinal number of each BPE token in the answer and its corresponding pixel value on the mask image. Consequently, each BPE token corresponds one-to-one with a pixel-level mask. The data ratios are summarized in Figure 2 (b). Figure 2 (c) and (d) further provide the number distribution of tokens per image type and a word cloud of the top 100 tokens, respectively.

image

The comparisons with other visual foundation models:

VFM Granularity Dataset #Image #Pairs
CLIP image-level WIT400M 400M 0.4B
DINO image-level ImageNet 14M -
SAM pixel-level SA1B 11M 1.1B
TokenOCR token-level TokenIT 20M 1.8B
TokenOCR

TokenOCR

Model Architecture

An overview of the proposed TokenOCR, where the token-level image features and token-level language features are aligned within the same semantic space. This “image-as-text” alignment seamlessly facilitates user-interactive applications, including text segmentation, retrieval, and visual question answering.

image

Model Cards

In the following table, we provide all models 🤗 link of the TokenOCR series. You can use prompt ' ' to get a highlight background.

Model Name Description
TokenOCR_2048_Bilingual_seg Backbone is ViT;feature dimension is 2048; support interactive with English and Chinese texts.
TokenOCR_4096_English_seg (We recommend 👍) Backbone is ViT; feature dimension is 4096; only supports interactive with English texts.

Evaluation on Vision Capability

We present a comprehensive evaluation of the vision encoder’s performance across various domains and tasks. The evaluation is divided into two key categories:

(1) text retrial; (2) image segmentation; (3) visual question answering;

This approach allows us to assess the representation quality of TokenOCR. Please refer to our technical report for more details.

text retrial

image

image segmentation

image

visual question answering

image
TokenVL

TokenVL

we employ the TokenOCR as the visual foundation model and further develop an MLLM, named TokenVL, tailored for document understanding. Following the previous training paradigm, TokenVL also includes two stages:

Stage 1: LLM-guided Token Alignment Training for text parsing tasks.

image

The framework of LLM-guided Token Alignment Training. Existing MLLMs primarily enhance spatial-wise text perception capabilities by integrating localization prompts to predict coordinates. However, this implicit method makes it difficult for these models to have a precise understanding. In contrast, the proposed token alignment uses BPE token masks to directly and explicitly align text with corresponding pixels in the input image, enhancing the MLLM’s localization awareness.

Stage 2: Supervised Instruction Tuning for VQA tasks.

During the Supervised Instruction Tuning stage, we cancel the token alignment branch as answers may not appear in the image for some reasoning tasks (e.g., How much taller is the red bar compared to the green bar?). This also ensures no computational overhead during inference to improve the document understanding capability. Finally, we inherit the remaining weights from the LLM-guided Token Alignment and unfreeze all parameters to facilitate comprehensive parameter updates.

OCRBench Results

image

Document Understanding Results

image

🤚 Release Plans

âś… Inference code and weights for TokenOCR

  • Release Character-level Text Image Foundation Model (CharOCR)
  • Code & model checkpoint for TokenVL
  • Data for the Pre-training and Fine-tuning of TokenVL
  • TokenIT data and script

🏛 License

This project is released under the MIT License.

📎 Citation

If you find this project useful in your research, please consider citing:

@inproceedings{guan2025TokenOCR,
  title={A Token-level Text Image Foundation Model for Document Understanding},
  author={Tongkun Guan, Zining Wang, Pei Fu, Zhentao Guo, Wei Shen, Kai zhou, Tiezhu Yue, Chen Duan, Hao Sun, Qianyi Jiang, Junfeng Luo, Xiaokang Yang},
  journal={arXiv preprint arXiv:2503.02304},
  year={2025}
}

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