README.md

---
license: apache-2.0
tags:
- vidore
- reranker
- qwen2_vl
---
# MonoQwen2-VL-2B-LoRA-Reranker

## Model Overview
The **MonoQwen2-VL-v0.1** is a LoRA of the Qwen2-VL-2B model, optimized for reranking (i.e, asserting pointwise image-query relevance) using the [MonoT5](https://arxiv.org/pdf/2101.05667) objective.
That is, given a couple of image and query fed into the prompt of the VLM, the model is tasked to generate "True" if the image is relevant to the query and "False" otherwise.
During inference, a relevancy score can then be obtained by comparing the logits of the two tokens and this score can effectively be used to rerank the candidates generated by a first-stage retriever (such as DSE or ColPali) or filter them using a threshold.

The [ColPali train set](https://huggingface.co/datasets/vidore/colpali_train_set) was used to train this model with negatives mined using DSE.

## How to Use the Model
Below is a quick example to rerank a single image against a user query using this model:

```python
import torch
from PIL import Image
from transformers import AutoProcessor, Qwen2VLForConditionalGeneration

# Load processor and model
processor = AutoProcessor.from_pretrained("Qwen/Qwen2-VL-2B-Instruct")
model = Qwen2VLForConditionalGeneration.from_pretrained(
    "lightonai/MonoQwen2-VL-v0.1",
    device_map="auto",
    # attn_implementation="flash_attention_2",
    # torch_dtype=torch.bfloat16,
)

# Define query and load image
query = "What is ColPali?"
image_path = "your/path/to/image.png"
image = Image.open(image_path)

# Construct the prompt and prepare input
prompt = (
    "Assert the relevance of the previous image document to the following query, "
    "answer True or False. The query is: {query}"
).format(query=query)

messages = [
    {
        "role": "user",
        "content": [
            {"type": "image", "image": image},
            {"type": "text", "text": prompt},
        ],
    }
]

# Apply chat template and tokenize
text = processor.apply_chat_template(messages, tokenize=False, add_generation_prompt=True)
inputs = processor(text=text, images=image, return_tensors="pt").to("cuda")

# Run inference to obtain logits
with torch.no_grad():
    outputs = model(**inputs)
    logits_for_last_token = outputs.logits[:, -1, :]

# Convert tokens and calculate relevance score
true_token_id = processor.tokenizer.convert_tokens_to_ids("True")
false_token_id = processor.tokenizer.convert_tokens_to_ids("False")
relevance_score = torch.softmax(logits_for_last_token[:, [true_token_id, false_token_id]], dim=-1)

# Extract and display probabilities
true_prob = relevance_score[0, 0].item()
false_prob = relevance_score[0, 1].item()

print(f"True probability: {true_prob:.4f}, False probability: {false_prob:.4f}")
```

This example demonstrates how to use the model to assess the relevance of an image with respect to a query. It outputs the probability that the image is relevant ("True") or not relevant ("False").

## Performance Metrics

The model has been evaluated on [ViDoRe Benchmark](https://huggingface.co/spaces/vidore/vidore-leaderboard), by retrieving 10 elements with [MrLight_dse-qwen2-2b-mrl-v1](https://huggingface.co/MrLight/dse-qwen2-2b-mrl-v1) and reranking them. The table below summarizes its `ndcg@5` scores:

| Dataset                                           | NDCG@5 Before Reranking  | NDCG@5 After Reranking |
|---------------------------------------------------|--------------------------|------------------------|
| **Mean**                                          | 85.8                     | **90.5**               |
| vidore/arxivqa_test_subsampled                    | 85.6                     | 89.01                  |
| vidore/docvqa_test_subsampled                     | 57.1                     | 59.71                  |
| vidore/infovqa_test_subsampled                    | 88.1                     | 93.49                  |
| vidore/tabfquad_test_subsampled                   | 93.1                     | 95.96                  |
| vidore/shiftproject_test                          | 82.0                     | 92.98                  |
| vidore/syntheticDocQA_artificial_intelligence_test| 97.5                     | 100.00                 |
| vidore/syntheticDocQA_energy_test                 | 92.9                     | 97.65                  |
| vidore/syntheticDocQA_government_reports_test     | 96.0                     | 98.04                  |
| vidore/syntheticDocQA_healthcare_industry_test    | 96.4                     | 99.27                  |
| vidore/tatdqa_test                                | 69.4                     | 78.98                  |


## License

This LoRA model is licensed under the Apache 2.0 license.