What is a .jp2 file?
JPEG 2000 · Image · Joint Photographic Experts Group / ISO · 2000
JP2 is the file format for JPEG 2000, a wavelet-based successor to classic JPEG that compresses more efficiently and supports a genuine lossless mode. It never caught on for everyday web photos, but it is the standard in medical imaging, digital archives and digital cinema.
What is a .jp2 file used for?
JPEG 2000 replaced JPEG's block-based DCT compression with wavelet compression, which avoids the blocky artefacts of a heavily compressed JPG and allows both lossy and mathematically lossless encoding in the same underlying format.
A signature feature is progressive, resolution-independent decoding: a viewer can pull a lower-resolution or lower-quality view straight from the same file without needing a separate small copy, which suits huge scans and satellite imagery well.
Despite the technical advantages, JP2 never displaced JPEG on the ordinary web, largely because mainstream browsers never added native support, Safari being the notable exception. It stayed standard instead in specialist fields: medical imaging (as part of DICOM), digital preservation, and cinema, where it forms the image data inside a Digital Cinema Package.
The format is defined by the ISO/IEC 15444 family of standards, with Part 1 covering the core codec and the .jp2 file format specifically.
How to open a .jp2 file
The .jp2 format opens in the following apps, grouped by operating system. If one app does not work, try another from the same list.
Windows
- IrfanView (with plugin)
- GIMP (with plugin)
- XnView
macOS
- Preview
- Safari
Linux
- GIMP (with OpenJPEG)
- ImageMagick
Web
- Safari natively; other browsers need conversion
How to convert a .jp2 file
You can convert a .jp2 file to PNG, JPG, TIFF using a conversion tool or the export menu of an app that opens it.
Convert images free: ImageConvert
.jp2 file signature (magic bytes)
Programs recognise a .jp2 file by the bytes at the start of the file, not by its name. These are the signatures for JP2. For a full breakdown, see the JP2 file signature page.
| Hex signature | Offset | Note |
|---|---|---|
| 00 00 00 0C 6A 50 20 20 0D 0A 87 0A | 0 | JP2 signature box |
See the full magic-numbers reference for every format.
Frequently asked questions
What is a .jp2 file?
JP2 is the file format for JPEG 2000, a wavelet-based successor to classic JPEG that compresses more efficiently and supports a genuine lossless mode. It never caught on for everyday web photos, but it is the standard in medical imaging, digital archives and digital cinema.
Why won't my JP2 file open in my browser?
Most browsers other than Safari never added native JPEG 2000 support, so a .jp2 usually needs a dedicated viewer or plugin, or converting to PNG or JPG for the web.
Is JPEG 2000 better than JPEG?
Technically yes, it compresses more efficiently and supports a genuine lossless mode, but its niche adoption outside medical imaging, digital preservation and cinema means ordinary JPG remains the practical choice for everyday photos.
Related formats
Sources
Details on this page were checked against authoritative references: