Asahi Kanji

Asahi Kanji application for Android™
Single kanji Handwriting Recognition

This is an experimental addition to the Asahi Kanji app.
For a presentation of the whole application please see:

   How to use:

ocr viewfinder

After tracing the character, tap the "Analyze" button.

ocr result
ocr result


Do not give up too quickly.
Just like the OCR feature you have to learn how to get the best of it.
Although counter intuitive, recognizing a single character can be a greater challenge for an OCR engine than recognizing a word made up of two kanji. Identifying a basic kanji made up of a few strokes is sometimes more difficult than recognizing one with a bigger number of strokes.
For example the Tesseract OCR engine cannot make the difference between 囗 and 口 , whatever the size of the drawn square on the screen.
The first one is a big square. It is the radical you find in the kanji 四 (four).
The second one, a smaller square, is the kanji "kuchi" (mouth, opening).
There are a few other similar cases, like 日 (sun), as Tesseract almost always returned the radical 曰 (the central horizontal stroke is a little shorter). For basic shapes Tesseract seems to favor radicals over kanji.
This is the reason why, until a better solution is found, the search results are limited to the Jōyō kanji.
For handwriting recognition all other characters and radicals (bushu) have been blacklisted.
Before that, 100% of the time, trying to display the card for 口 would display the message "Sorry, not a Jōyō kanji" or "Sorry, 曰 is not a Jōyō kanji", which is true. But we can imagine the comments on Google Play...

Your feedback, whether positive or negative, will be essential for the future development of this feature.
The handwriting function was developed and tested on a Google Galaxy Nexus, a standard device recommended for Android software development.

   What is the use of OCR limited to a single kanji?

The Asahi Kanji app was designed as a tool to help people review or memorize Japanese kanji.
For those who are lucky enough to study in Japan, the OCR function will be helpful.
Kanji are everywhere around us in the streets, trains, shops, on signboards and posters...
More than often a kanji that we “almost know” or “definitely knew but have forgotten” catches our eye.
We just need a “booster shot” at the right moment, in the right environment, for the character to stick in our mind.
This app tries to give you this possibility.


The OCR module uses the Tesseract OCR engine, released under the Apache License, Version 2.0

The OCR module user interface is based on an open source project developed by Robert Theis


Asahi Kanji does not collect nor transmit any information.

Up to version 1.3 this application did not require any particular permissions to run.

This Optical Character Recognition module (OCR) was introduced in version 1.4.0 and several permissions are now required.
When you downloaded an update or the app for the first time, Google Play used to display the following dialog box.

Today's messages will look different, as the Google Play interface keeps evolving all the time.

The wording like "full access", "view", modify or delete", "take pictures and videos" can understandably be frightening, although these actions are now standard on smartphones.
"full network access"

Network access is needed by the app in order to download two large files from
These files are the data needed by the Tesseract OCR engine to recognize Japanese characters.

"view network connections"

When you decide to download the files mentioned above, the app has to check if you have Internet access over wifi in order to display a message when it is not the case.

"modify or delete the contents of your USB storage"

The app needs to be able to copy the downloaded tarred (zipped) files to your USB storage and uncompress them. If the download process fails or is cancelled by the user, the app needs to delete the partially downloaded files before the next try.

"Take pictures and videos"

The Optical Character Recognition module needs access to your camera.
It does not take pictures nor videos though.
It just extracts the kanji image from the camera preview before sending it to the OCR engine.

As for Asahi Kanji JLPT-N5, it is a free demo that does not include OCR, does not require license checks nor any permissions to run.
It is also ad-free (no banners).

For further details send a message to

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