ujc to png

Download your puzzle designs from Nonograms Katana as simple images.


With this tool, nonogram authors can easily convert their own designs from the .ujc files exported from the app to normal .png images as follows.

  • Step 1: Export Your Data From The App

    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 menu named Other and select Save progress to file (zip) to export an archive of your data.

  • Step 2: Extract The Data Archive

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

  • Step 3: Drag and Drop Your Files Below

    Now, you can drag and drop the .ujc files in the area below; alternatively, you can tap on the same area to open a file picker dialog where you can select the files. After a short while, the converted images will appear in the gallery below ready to download.





  • How does this tool work?

    This tool analyzes the .ujc files generated by the app and extracts the contained png images that represent the nonogram pictures.

    To learn more, you can review the source code available on GitHub.

  • Who is this tool for?

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

  • Are my nonograms private?

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

  • Can I download nonograms made by other authors?

    No. To respect their work, this tool does not allow you to download nonograms made by other authors.

  • How many nonograms can I convert?

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

  • Why does nothing happen after I select the.ujc files?

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

  • Why do some images have transparent backgrounds?

    When the Recolor images option is not selected, images are extracted as-is from the .ujc files, which internally represent the background color of colored nonograms as transparent.

    To fix the final colors, enable the Recolor images option. 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 you selected in the app editor.

  • Why are the extracted images so small?

    If the Scale images option is set to 1, the final image dimensions correspond to the original dimensions of the nonogram. For example, a 20x20 nonogram becomes a tiny 20x20 pixels image.

    To save images in a larger format, increase the value of the Scale images option. For example, scaling a 20x20 nonogram by a value of 25 produces a larger 500x500 pixels image, since 20*25 = 500.

    Note that, similarly to the Recolor images option, this is a lossy operation and the final colors may be slightly different from the original ones you selected in the app editor.

  • Why does the Border radius option not work?

    Currently, this feature is supported only by some browsers. Make sure you are using the latest version of a supported browser and try increasing both the Scale images option and the Border radius option to a high value like 50 to verify that it works.

  • Why are the Dropzone, Options, and Gallery sections not visible?

    This can happen when something goes wrong when loading the tool. Make sure you are using an updated and supported browser that has Javascript enabled and try reloading the page.

  • Can I directly import png images into this tool?

    Yes. Just drag and drop them into the dropzone or select them in the file picker. After that you can manipulate them as usual with the available options. For example, you can use this tool to add pixel grid lines to your pixel art image.

  • Can I save my nonograms from the Nonograms Katana iOS app?

    No. Unfortunately, the Android and iOS versions of the Nonograms Katana app are different and the iOS version does not currently provide an option to export your nonograms to a local file.

    If you find a way to export or share .ujc files from the iOS app, please open an issue (see last question) so that we can update this answer.

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

    Please open an issue on Github, it's the fastest way to have your question seen.

Website created by Edoardo Scibona.