ujc to png

Export, convert and save your puzzle designs from Nonograms Katana as simple png images.


With this tool, nonogram authors can convert their own designs from the .ujc files generated by the app to standard .png images.

To start, open the Nonograms Katana Android app, then tap on the Settings icon in the top right corner; once in the settings, open the sub-menu named Other and select Save progress to file (zip) to export an archive of your data.

Using your preferred file manager, extract the NonogramsKatana.zip archive so that the sub-folder named MyNonograms becomes accessible. This folder contains all the nonograms created by you saved as .ujc files.

Now, you can drag and drop these files in the area below; alternatively, you can click or tap on the area to open a dialog where you can select .ujc files. The converted images will appear in the gallery below.

Your Nonograms

No nonograms found, try opening some .ujc files.


How does this work?

This tool analyzes the .ujc files exported from the Nonograms Katana app and extracts the png images representing the nonogram designs; to learn more, you can review the source code available on GitHub.

Who is this for?

This tool is aimed at nonogram authors who want to backup their own designs and have them available as images.

Are my nonograms private?

Yes. This tool works entirely in your browser and no file ever leaves your device.

Can I download nonograms from other authors?

No. This tool does not download nonograms from the Nonograms Katana app.

How many nonograms can I convert?

As many as you want. Note however that the more nonograms you select the slower the process will be, especially on less powerful devices.

Why nothing happens after I select the .ujc files?

On less powerful devices, the conversion process can take a few seconds. Either wait a little before retrying or convert fewer nonograms at a time.

Why are the extracted images so small?

When the Raw Images option is selected, images are extracted as-is from the .ujc files and the final dimensions reflect the original dimensions of the nonograms. For example, a 20x20 nonogram becomes a 20 by 20 pixels image.

To save images in a larger format, select one of the Recolor and scale options. For example, scaling a 20x20 nonogram with the Recolor and scale 25x option produces a 500 by 500 pixels image.

Why do some images have transparent backgrounds?

When the Raw Images option is selected, images are extracted as-is from the .ujc files, which represent the background color of colored nonograms as transparent.

To fix the final colors, select one of the Recolor options. Note however that due to the way that browsers work, this is a lossy operation and the final colors may be slightly different from the original ones.

Why can't I save my nonograms from the Nonograms Katana iOS app?

The Android and iOS versions of the Nonograms Katana app are different. Unfortunately, the iOS version does not currently support saving your nonograms to a local zip file.

I found an error / I want to ask another question.

Please open an issue on Github.