Image MIME Reference
HEJ2K
JPEG 2000 Image (HEIF Container)
image/hej2k
VS
JPEG XS Codestream
image/jxsc
JPEG-XS-Codestream
A complete technical comparison of JPEG 2000 Image (HEIF Container) and JPEG XS Codestream — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | HEJ2K | JPEG-XS-Codestream |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
JPEG 2000 Image (HEIF Container)
image/hej2k
Extension
.hej2
Container
HEIF / ISOBMFF (ISO/IEC 15444-16)
Compression
Lossy / Lossless
Algorithm
JPEG 2000HTJ2K
Color Depth
8-bit, 10-bit, 12-bit, 16-bit
Developed by
ISO/IEC JTC 1 / ITU-T
Released
2019
Magic Bytes
XX XX XX XX 66 74 79 70 6A 32 6B 69
JPEG XS Codestream
image/jxsc
Extension
.jxsc.jxs
Container
None (Raw Codestream)
Compression
Lossy (Visually Lossless) / Mathematically Lossless
Algorithm
JPEG XS (ISO/IEC 21122-1)
Color Depth
8-bit, 10-bit, 12-bit, 14-bit, 16-bit
Developed by
Joint Photographic Experts Group (JPEG) / intoPIX
Released
2019
Magic Bytes
FF 10
Browser Support Comparison
| Browser | HEJ2K | JPEG-XS-Codestream |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
HEJ2K
HEJ2K Strengths
- Brings the extensive capabilities of the HEIF container (like EXIF/XMP, thumbnails, and depth maps) to JPEG 2000
- Supports mathematically lossless compression via wavelet transformation
- High scalability and progressive decoding out of the box
Limitations
- Extremely limited software support outside of niche industries
- Zero native compatibility with web browsers
- High computational complexity compared to simpler formats like JPEG or PNG
JPEG-XS-Codestream
JPEG-XS-Codestream Strengths
- Eliminates container overhead, maximizing parsing speed and minimizing latency to fractions of a millisecond
- Highly optimized for direct hardware implementation in FPGAs and ASICs
- Perfect for continuous data streaming over IP networks without needing to establish file headers
Limitations
- Lacks standard container metadata (EXIF, XMP, ICC profiles), meaning color space and orientation data must be handled externally or out-of-band
- Zero support in web browsers or standard consumer operating systems
- Often requires specialized broadcast hardware or custom software libraries to decode
When to choose which format
HEJ2K
Use HEJ2K when…
- Medical Imaging
- Geospatial Data
- Scientific Archiving
JPEG-XS-Codestream
Use JPEG-XS-Codestream when…
- Hardware Decoding Pipelines (FPGA/ASIC)
- Live Broadcast Infrastructure
- Video over IP Transport
- Embedded Camera Systems