cxz / kmnist

Repository for Kuzushiji-MNIST, Kuzushiji-49, and Kuzushiji-Kanji

Kuzushiji-MNIST

📚 Read the paper to learn more about Kuzushiji, the datasets and our motivations for making them!

Kuzushiji-MNIST is a drop-in replacement for the MNIST dataset (28x28 grayscale, 70,000 images), provided in the original MNIST format as well as a NumPy format. Since MNIST restricts us to 10 classes, we chose one character to represent each of the 10 rows of Hiragana when creating Kuzushiji-MNIST.

Kuzushiji-49, as the name suggests, has 49 classes (28x28 grayscale, 270,912 images), is a much larger, but imbalanced dataset containing 48 Hiragana characters and one Hiragana iteration mark.

Kuzushiji-Kanji is an imbalanced dataset of total 3832 Kanji characters (64x64 grayscale, 140,426 images), ranging from 1,766 examples to only a single example per class.

The 10 classes of Kuzushiji-MNIST, with the first column showing each character's modern hiragana counterpart.

Get the data 💾

🌟 You can run python download_data.py to interactively select and download any of these datasets!

Kuzushiji-MNIST

Kuzushiji-MNIST contains 70,000 28x28 grayscale images spanning 10 classes (one from each column of hiragana), and is perfectly balanced like the original MNIST dataset (6k/1k train/test for each class).

File	Examples	Download (MNIST format)	Download (NumPy format)
Training images	60,000	train-images-idx3-ubyte.gz (18MB)	kmnist-train-imgs.npz (18MB)
Training labels	60,000	train-labels-idx1-ubyte.gz (30KB)	kmnist-train-labels.npz (30KB)
Testing images	10,000	t10k-images-idx3-ubyte.gz (3MB)	kmnist-test-imgs.npz (3MB)
Testing labels	10,000	t10k-labels-idx1-ubyte.gz (5KB)	kmnist-test-labels.npz (5KB)

We recommend using standard top-1 accuracy on the test set for evaluating on Kuzushiji-MNIST.

Which format do I download?

If you're looking for a drop-in replacement for the MNIST or Fashion-MNIST dataset (for tools that currently work with these datasets), download the data in MNIST format.

Otherwise, it's recommended to download in NumPy format, which can be loaded into an array as easy as:
arr = np.load(filename)['arr_0'].

Kuzushiji-49

Kuzushiji-49 contains 270,912 images spanning 49 classes, and is an extension of the Kuzushiji-MNIST dataset.

File	Examples	Download (NumPy format)
Training images	232,365	k49-train-imgs.npz (63MB)
Training labels	232,365	k49-train-labels.npz (200KB)
Testing images	38,547	k49-test-imgs.npz (11MB)
Testing labels	38,547	k49-test-labels.npz (50KB)

We recommend using balanced accuracy on the test set for evaluating on Kuzushiji-49.

Kuzushiji-Kanji

Kuzushiji-Kanji is a large and highly imbalanced 64x64 dataset of 3832 Kanji characters, containing 140,426 images of both common and rare characters.

The full dataset is available for download here (310MB).
We plan to release a train/test split version as a low-shot learning dataset very soon.

Benchmarks & Results 📈

Have more results to add to the table? Feel free to submit an issue or pull request!

Model	MNIST	Kuzushiji-MNIST	Kuzushiji-49
4-Nearest Neighbour Baseline	97.14%	91.56%	86.01%
Keras Simple CNN Benchmark	99.06%	95.12%	89.25%
PreActResNet-18	99.56%	97.82%	96.64%
PreActResNet-18 + Input Mixup	99.54%	98.41%	97.04%
PreActResNet-18 + Manifold Mixup	99.54%	98.83%	97.33%

For MNIST and Kuzushiji-MNIST we use a standard accuracy metric, while Kuzushiji-49 is evaluated using balanced accuracy (so that all classes have equal weight).

License

Both the dataset itself and the contents of this repo are licensed under a permissive CC BY-SA 4.0 license, except where specified within some benchmark scripts. CC BY-SA 4.0 license requires attribution, and we would suggest to use the following attribution to the KMNIST dataset.

"KMNIST Dataset" (created by CODH), adapted from "Kuzushiji Dataset" (created by NIJL and others), doi:10.20676/00000341

Citing Kuzushiji-MNIST

If you use any of the Kuzushiji datasets in your work, we would appreciate a reference to our paper:

Deep Learning for Classical Japanese Literature. Tarin Clanuwat et al. arXiv:1812.01718

@online{clanuwat2018deep,
  author       = {Tarin Clanuwat and Mikel Bober-Irizar and Asanobu Kitamoto and Alex Lamb and Kazuaki Yamamoto and David Ha},
  title        = {Deep Learning for Classical Japanese Literature},
  date         = {2018-12-03},
  year         = {2018},
  eprintclass  = {cs.CV},
  eprinttype   = {arXiv},
  eprint       = {cs.CV/1812.01718},
}

Related datasets

Kuzushiji Dataset http://codh.rois.ac.jp/char-shape/ offers 3,999 character types and 403,242 character images with CSV files containing the bounding box of characters on the original page images. At this moment, the description of the dataset is available only in Japanese, but the English version will be available soon.