Add dataset card

README.md

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+---
+pretty_name: ocr_data
+task_categories:
+- image-to-text
+language:
+- ar
+tags:
+- ocr
+- arabic
+- synthetic
+- webdataset
+---
+
+# ocr_data
+
+Synthetic Arabic document images with layout annotations, for OCR training.
+
+## Layout
+
+WebDataset `.tar` shards. Files sharing a basename are one sample, so the
+image becomes the `image` column and the annotation the `json` column.
+
+```
+data/<contributor>_<NNN>.tar            originals (PNG + JSON)
+data_aug/<contributor>_<NNN>_aug<K>.tar augmented variants (JPEG/PNG + JSON)
+```
+
+Each shard holds up to 9990 samples (~1.2 GB). `data/` and `data_aug/`
+are separate so you can train on clean originals alone.
+
+## Loading
+
+```python
+from datasets import load_dataset
+
+# one shard
+ds = load_dataset("webdataset",
+                  data_files="hf://datasets/OCR-Data-new/ocr_data/data/<contributor>_001.tar",
+                  split="train", streaming=True)
+
+# a range of shards
+ds = load_dataset("webdataset",
+                  data_files="hf://datasets/OCR-Data-new/ocr_data/data/<contributor>_{001..010}.tar",
+                  split="train", streaming=True)
+
+# everything, originals + augmented
+ds = load_dataset("webdataset", data_files={"train": [
+        "hf://datasets/OCR-Data-new/ocr_data/data/*.tar",
+        "hf://datasets/OCR-Data-new/ocr_data/data_aug/*.tar"]},
+      split="train", streaming=True)
+```
+
+To get loose files back, use `unpack_shard.py` from the generator repo.
+
+## Annotation schema
+
+```json
+{
+  "dimensions": {"width": 0, "height": 0},
+  "blocks":  [{"type": "...", "text": "...", "top_left_x": 0, "top_left_y": 0,
+                "bottom_right_x": 0, "bottom_right_y": 0, "reading_index": 0}],
+  "images":  [{"top_left_x": 0, "...": 0}],
+  "meta":    {"template": "...", "hybrid": null, "page_font": "...",
+               "language": "ar", "script": "arabic", "direction": "rtl",
+               "augmentation": null}
+}
+```
+
+`meta.augmentation` is `null` for originals and
+`{"name": ..., "params": {...}}` for augmented variants.