First update on the dataset card

README.md

@@ -9,13 +9,70 @@ dataset_info:
     dtype: image
   splits:
   - name: train
-    num_bytes: 1128223519.0
+    num_bytes: 1128223519
     num_examples: 476118
   download_size: 879225634
-  dataset_size: 1128223519.0
+  dataset_size: 1128223519
 configs:
 - config_name: default
   data_files:
   - split: train
     path: data/train-*
+license: gpl-3.0
 ---
+# Dataset Summary
+This is a simple dataset that I crawled (with labels) from the Internet.
+As its title suggests, the dataset contains Captcha images.
+One downloads and uses this dataset as usual:
+
+```ipython
+In [1]: from datasets import load_dataset
+
+In [2]: dataset = load_dataset("phunc20/nj_biergarten_captcha)
+```
+
+The structure of the dataset is depicted in the following code
+
+```ipython
+In [3]: dataset
+Out[3]:
+DatasetDict({
+    train: Dataset({
+        features: ['__key__', '__url__', 'jpg'],
+        num_rows: 476118
+    })
+})
+
+In [4]: dataset["train"][0]["__key__"]
+Out[4]: '001/2024-10-08T18:21:10.578994_y2jhuv'
+
+In [5]: dataset["train"][0]["__url__"]
+Out[5]: '/home/phunc20/git-repos/huggingface_hub/phunc20/nj_biergarten_captcha/001.tar'
+
+In [6]: dataset["train"][0]["jpg"]
+Out[6]: <PIL.JpegImagePlugin.JpegImageFile image mode=RGB size=140x50>
+```
+
+- The `__key__` key's value contains part of the file's path; in particular,
+  the groundtruth Captcha (aka label) lies in this string,
+  which, in the above example, is `y2jhuv`, right after the understore sign `'_'`.
+  This retrieval pattern of label is universal across the entire dataset.
+    - One thing to notice is that the set of symbols appearing in this Captcha
+      dataset is `[a-z][1-9]`, or in Python's term, `string.ascii_lowercase + string.digits[1:]`.
+      `0` is excluded on purpose because this Captcha generator generates hard-to-distinguish
+      zeros and little-oh-s.
+- The `__url__` key is normally of no interesting usage.
+- The `"jpg"` key's value is a `PIL.Image` (obtained from the original JPEG file).
+
+An immediate usage of the dataset is to train a Captcha cracker.
+
+
+# Citation Information
+
+```
+@ONLINE{nj_biergarten_captcha,
+    author = "phunc20",
+    title  = "nj_biergarten_captcha",
+    url    = "https://huggingface.co/datasets/phunc20/nj_biergarten_captcha"
+}
+```