QOI to JP2 Converter
Convert QOI to JP2 in your browser. QOI files usually come from game engines, emulators and tools that want lossless images without a PNG library; JP2 is the better fit for archival masters and specialist imaging. You get a lossless JPEG 2000 (.jp2) using the reversible 5/3 wavelet. Nothing is uploaded.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
QOI expected · other image formats also work
How to use QOI to JP2
- 1
Add your QOI files: drop them here, choose them, or paste from the clipboard.
- 2
There is nothing to tune: the JP2 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 .jp2 files one at a time or together as a ZIP.
Why use Aback Images for qoi to jp2
Where the JP2 goes next
JP2 opens in macOS Preview, GIMP, IrfanView, XnView, ImageMagick and the OpenJPEG tools.
JP2 next to QOI
Both sides are lossless, so the size depends on how well the JP2 encoder handles this picture compared with the QOI's lossless, byte-aligned run, index, difference and literal codes.
Written without a lossy pass
The JP2 is written losslessly, so the pixels decoded from the QOI arrive unchanged.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
QOI vs JP2
What changes from QOI to JP2
Encoding: the QOI uses lossless, byte-aligned run, index, difference and literal codes; JP2 uses wavelet coding: reversible 5/3 for lossless files, irreversible 9/7 for lossy ones, and the download is a lossless JPEG 2000 (.jp2) using the reversible 5/3 wavelet.
Bit depth: 8 bits per channel in the QOI; JP2 allows up to 16 bits per channel is common, more is possible, and the JP2 written here has 8 bits per channel.
Colour: RGB or RGBA, tagged sRGB or linear in the QOI; JP2 supports sRGB, greyscale, YCC or a space described by an ICC profile, written here as 8-bit sRGB.
Transparency: the QOI stores it as a full 8-bit alpha channel; the JP2 keeps it as an extra component flagged as opacity.
Metadata: the QOI can carry none: a 14-byte header holds only size, channels and colour space; JP2 can carry XML, ICC and resolution boxes, but nothing is copied across.
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.
QOI files usually come from game engines, emulators and tools that want lossless images without a PNG library.
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.
When converting QOI to JP2 makes sense
JP2 is the better choice for archival masters and specialist imaging, while QOI suits fast lossless storage in games and tools.
JP2 strengths: True lossless mode; High bit depths and very large images; Standardised for archives and digital cinema. Drawbacks to weigh: Browsers do not display it; Slow to encode and decode; Patchy support in everyday apps.
Limitations
- QOI is lossless, so the pixels you get out are exactly the ones that went in.
- Lossless JPEG 2000 is larger than a lossy one, but usually smaller than an uncompressed TIFF of the same pixels.
- No current browser displays JP2 by default; archive and imaging software opens it.
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Frequently asked questions
Does converting QOI to JP2 lose quality?
JP2 is written losslessly, so the pixels are stored exactly as decoded.
Is transparency kept in the JP2?
Yes. QOI stores it as a full 8-bit alpha channel, and the JP2 is written with an alpha channel, so transparent areas stay transparent.
Is the JPEG 2000 file lossless?
Yes. It is written with JPEG 2000's reversible 5/3 wavelet, so decoding it gives back exactly the pixels that went in. The trade-off is size: a lossless JP2 is larger than a lossy one, though usually smaller than an uncompressed TIFF.
Which apps open JP2 files?
MacOS Preview, GIMP, IrfanView, XnView, ImageMagick and the OpenJPEG tools. It does not open in web browsers by default.
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.