JP2 to PNG Converter
You need to edit or reuse a JPEG 2000 picture and your editor does not read .jp2. PNG is a good target because it stores pixels exactly and keeps transparency. This converter decodes the JP2 on your own device and writes a PNG, with nothing uploaded and no software to install.
How to convert JP2 to PNG
- Add your JP2 files by dropping them, clicking the drop zone or pasting.
- The output format is already set to PNG. Adjust quality or size if you need to.
- Press Convert and compare the original and new size for each file.
- Download each file or all of them as a ZIP.
When to convert, and when not to
- You plan to retouch the picture and want to avoid another lossy save at the start.
- The JP2 has transparency that you want to keep for a design or web page.
- You need a widely supported copy for a tool that only reads PNG.
- Do not convert a huge scan to PNG without resizing it, because the lossless file can become very large.
What changes
- The picture is decoded by a WebAssembly decoder that downloads the first time you add a JP2 file.
- PNG stores the decoded pixels exactly, so this step adds no new quality loss.
- Any compression artefacts already in the JP2 stay as they are.
- There is no quality slider because PNG is lossless; use Resize to control the file size.
- Metadata in the JPEG 2000 file is not written to the PNG.
Why PNG suits a decoded JPEG 2000 picture
JPEG 2000 can be lossless or lossy depending on how the file was made. Once the picture is decoded, you have a grid of pixels, and PNG is a format that keeps such a grid exactly. That makes it a safe working format for editing, because opening and saving it does not degrade the picture further.
PNG also supports transparency. If the JP2 carries an alpha channel, the converted file keeps it, which is useful for graphics and for pictures that will sit on a coloured page.
File size is the catch
JPEG 2000 is efficient at storing very large pictures. PNG is not designed for that, so a big scan converted to PNG can produce a much larger file. That is not a sign that something went wrong. It is the price of storing every pixel exactly.
To keep the result manageable, choose the resize option and set a maximum width and height close to what you will really use. Convert one file first and look at the size shown next to it before running a large batch.
Memory and patience
Decoding JPEG 2000 is demanding, and the whole picture has to fit in your browser's memory while it is processed. On a phone or an older computer, convert one file at a time. If the tool tells you the picture is too large, reduce the size and try again. The first file takes the longest because the decoder downloads then.
Choosing between PNG and JPG for scans
If your JP2 is a document scan or a map, PNG keeps lines and text crisp, which is why it suits that kind of picture. For photographs, JPG is often the sensible choice once you have a copy you intend to share. You can run the same file through both and compare the sizes shown, then keep the one that fits your purpose.
Privacy: your files stay on your device
- The tool decodes, resizes and encodes your pictures with your browser. The files are never sent to a server.
- To check it yourself: open the browser developer tools (F12), open the Network tab, convert a file, and look for any request that carries your image. You will see none.
Frequently asked questions
Is PNG better than JPG for JP2 files?
It avoids new quality loss and keeps transparency, but the files are larger. JPG is better when size matters more than exactness.
Will the PNG look exactly like the JP2?
It will match the decoded picture. Flaws already in a lossy JP2 stay visible.
Why is my PNG so large?
PNG stores every pixel without discarding anything. Resize the picture to the size you need to shrink it.
Is transparency preserved?
Yes, if the JP2 contains it.
Does a quality slider apply?
No. PNG is lossless, so only resizing changes the size.
Is anything sent to a server?
No. The picture is decoded and saved inside this browser tab.