JP2 to QOI Converter
Convert JP2 to QOI in your browser. JP2 files usually come from libraries and digital archives, medical (DICOM) and satellite imaging, and digital cinema packages; QOI is the better fit for fast lossless storage in games and tools. You get a lossless RGBA QOI file. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
JP2 expected · other image formats also work
How to use JP2 to QOI
- 1
Add your JP2 files: drop them here, choose them, or paste from the clipboard.
- 2
There is nothing to tune: the QOI is written losslessly. Resizing and rotating are under More options if you need them.
- 3
Click Convert. Each file is decoded and encoded in a background thread on this device.
- 4
Download the .qoi files one at a time or together as a ZIP.
Why use Aback Images for jp2 to qoi
Where the QOI goes next
QOI opens in game engines, GIMP 3, ImageMagick, XnView MP and many small libraries.
QOI next to JP2
Both sides are lossless, so the size depends on how well the QOI encoder handles this picture compared with the JP2's wavelet coding: reversible 5/3 for lossless files, irreversible 9/7 for lossy ones.
Written without a lossy pass
The QOI is written losslessly, so the pixels decoded from the JP2 arrive unchanged, apart from precision beyond 8 bits per channel.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
JP2 vs QOI
What changes from JP2 to QOI
Encoding: the JP2 uses wavelet coding: reversible 5/3 for lossless files, irreversible 9/7 for lossy ones; QOI uses lossless, byte-aligned run, index, difference and literal codes, and the download is a lossless RGBA QOI file.
Bit depth: up to 16 bits per channel is common, more is possible in the JP2; QOI allows 8 bits per channel, and the QOI written here has 8 bits per channel. 12 and 16-bit JPEG 2000 files are reduced to 8 bits per channel.
Colour: sRGB, greyscale, YCC or a space described by an ICC profile in the JP2; QOI supports RGB or RGBA, tagged sRGB or linear, written here as 8-bit sRGB.
Transparency: the JP2 stores it as an extra component flagged as opacity; the QOI keeps it as a full 8-bit alpha channel.
Metadata: the JP2 can carry XML, ICC and resolution boxes; QOI can carry none: a 14-byte header holds only size, channels and colour space, but nothing is copied across.
About JP2
JPEG 2000 is a wavelet-based format that can be truly lossless or lossy, handles very high bit depths and huge images, and is used where long-term fidelity matters: archives, medicine, satellites and digital cinema.
A .jp2 file is a box structure: a 12-byte signature box, an 'ftyp' box, a 'jp2h' header box with the size and colour specification, then the 'jp2c' box holding the codestream, which begins with FF 4F FF 51.
JP2 files usually come from libraries and digital archives, medical (DICOM) and satellite imaging, and digital cinema packages.
About QOI
QOI is a modern lossless format that encodes 20-50 times faster than PNG with similar file sizes. It is popular in games and tools that value speed and simplicity.
A QOI file is a 14-byte header ('qoif', width, height, channels, colour space), a stream of chunks that each encode a run, an index into 64 recently seen colours, a small difference from the previous pixel or a literal value, and an 8-byte end marker.
When converting JP2 to QOI makes sense
QOI is the better choice for fast lossless storage in games and tools, while JP2 suits archival masters and specialist imaging.
QOI strengths: Extremely fast lossless encode and decode; Simple, open spec. Drawbacks to weigh: Not supported by browsers or mainstream apps.
Limitations
- A JPEG 2000 file may be a lossless master or a lossy derivative; the file does not tell you which at a glance, so keep the original either way.
- Archival scans can be tens of thousands of pixels across, and decoding them needs a lot of memory on a phone.
- Browsers and most mainstream apps cannot open QOI; it is meant for games and tools that read it directly.
- QOI files are usually close to PNG in size but much faster to encode and decode.
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Frequently asked questions
Does converting JP2 to QOI lose quality?
QOI is written losslessly, so the pixels are stored exactly as decoded. 12 and 16-bit JPEG 2000 files are reduced to 8 bits per channel.
Is transparency kept in the QOI?
Yes. JP2 stores it as an extra component flagged as opacity, and the QOI is written with an alpha channel, so transparent areas stay transparent.
Which apps open QOI files?
Game engines, GIMP 3, ImageMagick, XnView MP and many small libraries. It does not open in web browsers.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.