---
language:
- tt
license: cc-by-4.0
pretty_name: Tatar OCR Benchmark
size_categories:
- n<1K
task_categories:
- image-to-text
tags:
- ocr
- document-understanding
- tatar
- historical-documents
---

# Tatar OCR Benchmark

This dataset is a page-level OCR benchmark for Tatar documents.
Each item contains:
- the original page image,
- structured OCR/layout annotations in JSONL,
- a visual control image for fast human verification (`original | reconstructed`).

Full original page images are included.

## Acknowledgements

We express our appreciation to [Yandex LLC](https://huggingface.co/yandex) for support in dataset collection.

## What Is Included

Export folder structure:
- `images/...` original page images
- `control/...` control images (left: original, right: reconstructed)
- `dataset.jsonl` one JSON object per page

## JSONL Schema (`dataset.jsonl`)

Top-level fields per row:
- `page_id` (`int`) stable internal page identifier
- `image` (`str`) relative path to original image (under `images/`)
- `control` (`str`) relative path to control image (under `control/`)
- `width` (`int`) original image width in pixels
- `height` (`int`) original image height in pixels
- `items` (`list[object]`) ordered OCR/layout objects

`items[]` fields:
- `order` (`int`) reading order
- `layout_id` (`int`) stable internal bbox identifier
- `class_name` (`str`) layout class
- `bbox` (`object`) normalized coordinates:
  - `x1`, `y1`, `x2`, `y2` (`float`, range `[0,1]`)
- `content_format` (`str`, optional) output format (`markdown`, `html`, `latex`, etc.)
- `content` (`str`, optional) OCR content
- `caption_targets` (`list[int]`, caption-only) referenced `layout_id` targets

Notes:
- `picture` items typically do not contain `content`/`content_format`.
- `page_id` and `layout_id` are kept intentionally for stable linking and reproducibility.

 ## Example Row
```json
{
  "page_id": 42,
  "image": "images/misc/001000.png",
  "control": "control/misc/001000.png",
  "width": 1408,
  "height": 1088,
  "items": [
    {
      "order": 1,
      "layout_id": 1835,
      "bbox": {
        "x1": 0.0557,
        "y1": 0.0958,
        "x2": 0.109,
        "y2": 0.167
      },
      "class_name": "picture"
    },
    {
      "order": 2,
      "layout_id": 1829,
      "bbox": {
        "x1": 0.1144,
        "y1": 0.0966,
        "x2": 0.3049,
        "y2": 0.1648
      },
      "class_name": "text",
      "content_format": "markdown",
      "content": "БӨТЕНДӨНЬЯ ТАТАР\nЯШЬЛӘРЕ ФОРУМЫ"
    },
    {
      "order": 3,
      "layout_id": 1830,
      "bbox": {
        "x1": 0.1026,
        "y1": 0.2243,
        "x2": 0.6247,
        "y2": 0.3098
      },
      "class_name": "section_header",
      "content_format": "markdown",
      "content": "#### СЕРТИФИКАТ"
    },
    {
      "order": 4,
      "layout_id": 1834,
      "bbox": {
        "x1": 0.1199,
        "y1": 0.3424,
        "x2": 0.2885,
        "y2": 0.3751
      },
      "class_name": "text",
      "content_format": "markdown",
      "content": "ТАПШЫРЫЛА"
    },
    {
      "order": 5,
      "layout_id": 1831,
      "bbox": {
        "x1": 0.1942721496928822,
        "y1": 0.6072256985832664,
        "x2": 0.6748469959605824,
        "y2": 0.687212719636805
      },
      "class_name": "text",
      "content_format": "markdown",
      "content": "*\"Татарча диктант\" белем бирү*\n*акциясендә катнашкан өчен*"
    },
    {
      "order": 6,
      "layout_id": 1832,
      "bbox": {
        "x1": 0.6836,
        "y1": 0.7307,
        "x2": 0.9285,
        "y2": 0.9422
      },
      "class_name": "text",
      "content_format": "markdown",
      "content": "**Татарча\nдиктант**\n\n**ЯЗ.**"
    },
    {
      "order": 7,
      "layout_id": 1833,
      "bbox": {
        "x1": 0.32613049853931775,
        "y1": 0.873131134930779,
        "x2": 0.6471898772499778,
        "y2": 0.9243139940149644
      },
      "class_name": "text",
      "content_format": "markdown",
      "content": "*Ихтирам белән, Бөтендөнья татар*\n*яшьләре форумы рәисе Т.М. Яруллин*"
    }
  ]
}
```

## Control Image Semantics

`control` image is horizontal:
- left half: original image
- right half: reconstructed rendering from the same JSON row

Reconstruction uses the same exported `items` as source of truth:
- same bbox coordinates,
- same class,
- same order,
- same content.

Each rendered box includes:
- class label,
- reading order,

Key decisions applied:
- OCR preserves source text strictly; typos/errors are not corrected.
- Diacritics are preserved strictly; no simplification to look-alike characters.
- Header hierarchy is preserved; default header level may be adjusted by page context.
- Multi-line headers preserve line breaks (e.g., with `<br>` in markdown workflow rules).

## Intended Use

- OCR benchmarking for Tatar historical/printed documents
- OCR post-processing and reconstruction evaluation

## Dataset Evolution Notice

This dataset is an actively evolving benchmark and is subject to change.

Possible updates in future versions include:
- additional pages and sources,
- annotation corrections and quality improvements,
- updated normalization/formatting decisions.

Where possible, backward compatibility will be preserved, but consumers should treat the schema as versioned and monitor release notes.
  
## Limitations

- Current size is small (50 items) and will be expanded.
- Source domain/style coverage is still limited at this stage.
- Some hard OCR cases (quality, uncertainty, complex regions) remain challenging.

## Citation

If you use this dataset, please cite:
- `yasalma/tatar-ocr-benchmark` (Hugging Face)