README.md

---
dataset_info:
- config_name: attribute_grounding_and_alignment
  features:
  - name: idx
    dtype: int32
  - name: imgname
    dtype: string
  - name: chart_type
    dtype: string
  - name: attribute
    dtype: string
  - name: chart_1_grounding
    dtype: string
  - name: chart_2_grounding
    dtype: string
  - name: alignment_json
    dtype: string
  - name: image_pair
    dtype: image
  splits:
  - name: test
    num_bytes: 144273203.125
    num_examples: 1751
  download_size: 140665127
  dataset_size: 144273203.125
- config_name: data_grounding_and_alignment
  features:
  - name: idx
    dtype: int32
  - name: imgname
    dtype: string
  - name: chart_type
    dtype: string
  - name: num_cell_difference
    dtype: int32
  - name: chart_1_grounding
    dtype: string
  - name: chart_2_grounding
    dtype: string
  - name: alignment_json
    dtype: string
  - name: image_pair
    dtype: image
  splits:
  - name: test
    num_bytes: 391677829.125
    num_examples: 4287
  download_size: 382856565
  dataset_size: 391677829.125
- config_name: robustness
  features:
  - name: idx
    dtype: int32
  - name: set_idx
    dtype: int32
  - name: set_pair_idx
    dtype: int32
  - name: imgname
    dtype: string
  - name: chart_type
    dtype: string
  - name: num_cell_difference
    dtype: int32
  - name: attribute_varied
    dtype: string
  - name: alignment_json
    dtype: string
  - name: image_pair
    dtype: image
  splits:
  - name: test
    num_bytes: 1339741262.125
    num_examples: 16575
  download_size: 1277778734
  dataset_size: 1339741262.125
configs:
- config_name: attribute_grounding_and_alignment
  data_files:
  - split: test
    path: attribute_grounding_and_alignment/test-*
- config_name: data_grounding_and_alignment
  data_files:
  - split: test
    path: data_grounding_and_alignment/test-*
- config_name: robustness
  data_files:
  - split: test
    path: robustness/test-*
---

## 📊 ChartAlignBench
[**📖 Paper**](https://arxiv.org/abs/2510.26781) | [**💻 GitHub**](https://github.com/tianyi-lab/ChartAlignBench/)

ChartAlignBench is a multi-modal benchmark designed to evaluate vision-language models (VLMs) on dense-level chart grounding and multi-chart alignment to comprehensively assess fine-grained chart understanding in VLMs. 


### 🌐 Overview

ChartAlignBench contains 9K+ instances, divided into three evaluation subsets:-
1. Data Grounding & Alignment: Paired charts differ in underlying data values visualized by the chart.
2. Attribute Grounding & Alignment: Paired charts differ in visualization attribute e.g., color, legend or text style.
3. Robustness: Multiple variants of paired charts for Data Alignment, with different attributes across variants.   

<p align="left">
  <img src="dataset_examples.png" width="85%">
  <em>Examples of chart pairs in ChartAlignBench.</em>
</p>


### 📃 Instruction

For each subset, the test*.parquet files contain the annotations and image pairs pre-loaded for processing with HF Datasets.

```
from datasets import load_dataset

data_grounding_and_alignment_subset = load_dataset("umd-zhou-lab/ChartAlignBench", "data_grounding_and_alignment")
attribute_grounding_and_alignment_subset = load_dataset("umd-zhou-lab/ChartAlignBench", "attribute_grounding_and_alignment")
robustness_subset = load_dataset("umd-zhou-lab/ChartAlignBench", "robustness")

```

### 📂 Dataset Description


#### Common fields (all subsets)
| Field |	Description |
|-------|---------------|
|idx |	Unique index of the sample in the set |
|imgname | Name of the chart image |
|chart_type | Type of chart|
|alignment_json | Alignment label for the chart pair |
|image_pair | Image of horizontally stitched chart pair (PIL.Image) | 


#### Data Grounding and Alignment 
| Field |	Description |
|-------|---------------|
|num_cell_difference | Number of data points which differ between the chart pair |
|chart_1_grounding | Grounding label for chart 1 (csv table) |
|chart_2_grounding |	Grounding label for chart 2 (csv table) |

#### Attribute Grounding and Alignment 
| Field |	Description |
|-------|---------------|
|attribute | Attribute which differs between the chart pair |
|chart_1_grounding | Grounding label for chart 1 (json) |
|chart_2_grounding | Grounding label for chart 2 (json) |

#### Robustness
| Field |	Description |
|-------|---------------|
| set_idx | Set index which groups the 5 chart pairs in a robustness set |
| set_pair_idx | Pair index within a set (1-5) |
|num_cell_difference | Number of data points which differ between the chart pair |
|attribute_varied | Attribute which varies across the 5 chart pairs |