What is the JPX file format?
A .jpx file is an extended JPEG 2000 image defined by ISO/IEC 15444-2 (JPEG 2000 Part 2: Extensions), first published in 2004 with the most recent edition in 2021. It builds on the baseline .JP2 format by adding capabilities including extended and arbitrary ICC colour spaces, multiple codestreams within a single file, compositing and layering similar to PDF layers, and animation support.
The container uses the same ISO box-based structure as .jp2, but the File Type (ftyp) box carries the brand identifier jpx (four bytes with a trailing space). Image data is compressed using JPEG 2000's discrete wavelet transform (DWT) with EBCOT entropy coding, supporting both lossless and lossy modes at up to 16 bits per component across up to 255 channels - covering greyscale, RGB, CMYK, and arbitrary multi-channel configurations.
.jpx and .jpf are two extensions for the same ISO 15444-2 format; ISO recommends .jpf for desktop files, but .jpx is more widely encountered in software. A .jpx file may be backward-compatible with .jp2 readers if it uses only Part 1 features, or may require a full Part 2 decoder.
As of 2026, only Apple Safari among major browsers renders JPEG 2000 natively. Tools with support include Adobe Photoshop, IrfanView (with the JPEG 2000 plugin), XnView MP, and ImageMagick.
Security & safety
RISK: LOWA JPX is a passive image with no scripting - it cannot run code on opening. The realistic risk is decoder bugs: JPEG 2000 Part 2 decoding is complex, and malformed files have historically triggered memory-corruption flaws in image libraries such as OpenJPEG. Keep viewers and OS image codecs updated, and be cautious opening .jpx files from untrusted sources in outdated tools. For normal use it is as safe as any image file.
Format details
in a nutshellPrograms that open JPX files
Windows6 apps
Adobe Photoshop
Paid Opens JPEG 2000 files including .jpx natively; File > Open, then Save As another format. 
GIMP
Open-source Opens JPEG 2000 via OpenJPEG; File > Open the .jpx and Export As JPG/PNG. Free Photoshop alternative. 
IrfanView (+ JPEG 2000 plugin)
Free Install IrfanView and its PlugIns pack (adds the JPEG 2000 codec), then open the .jpx; File > Save As to convert to JPG/PNG. 
macOS2 apps
Apple Preview
Built-in macOS opens JPEG 2000 natively in Preview - double-click to view; File > Export to JPEG/PNG. 
Linux3 apps
ImageMagick (CLI)
Open-source magick input.jpx output.png (needs OpenJPEG delegate) - scriptable batch conversion.
Apple Safari
Built-in Only major browser that renders JPEG 2000 - drag the file into a Safari tab on macOS/iOS. Technical details
deep spec| Standard | ISO/IEC 15444-2:2021 (4th edition; JPEG 2000 Part 2: Extensions) |
| Magic bytes | 00 00 00 0C 6A 50 20 20 0D 0A 87 0A (12-byte JPEG 2000 family signature, shared with .jp2) |
| ftyp brand | jpx (4 bytes with trailing space, at offset 20; distinguishes JPX from JP2) |
| Container | JP2 box-based (ISO/IEC 15444-12) |
| Compression | Wavelet (DWT-based JPEG 2000 codestream; EBCOT entropy coding); lossy or lossless |
| Encoding | Binary |
| Byte order | Big-endian |
| Color depth | 1-16 bpp per component; up to 255 components |
| Color space support | RGB, CMYK, Grayscale, arbitrary ICC profiles; Part 2 adds extended and enumerated colour spaces |
| Canvas size limit | Up to 2^32 × 2^32 pixels (theoretical JPEG 2000 maximum) |
| MIME type | image/jpx (IANA registered, RFC 3745, 2004) |
| Alternate extension | .jpf - same ISO 15444-2 format; ISO recommends .jpf for desktop use |
| Browser support | Apple Safari only as of 2026; no other major browser renders JPEG 2000 natively |
| Released | JPEG 2000 Part 2 (Extensions), ISO/IEC 15444-2, published 2004 |
| Latest version | ISO/IEC 15444-2:2021 (4th edition) |
| Open standard | Yes · royalty-free |
| Specification | www.iso.org |
JPX conversions
Community Q&A
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