Image MIME Reference
JPX
JPEG 2000 Part 2 (Extended)
image/jpx
VS
Radiance HDR
image/vnd.radiance
Radiance
A complete technical comparison of JPEG 2000 Part 2 (Extended) and Radiance HDR — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | JPX | Radiance |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
JPEG 2000 Part 2 (Extended)
image/jpx
Extension
.jpx.jpf
Container
ISOBMFF / JPX (ISO/IEC 15444-2)
Compression
Lossy / Lossless
Algorithm
Discrete Wavelet Transform (DWT)
Color Depth
8-bit, 16-bit, 32-bit, 38-bit
Developed by
Joint Photographic Experts Group (JPEG)
Released
2002
Magic Bytes
00 00 00 0C 6A 50 20 20 0D 0A 87 0A ... 66 74 79 70 6A 70 78 20
Radiance HDR
image/vnd.radiance
Extension
.hdr.pic.rgbe.xyze
Container
Radiance Information Header
Compression
Run-Length Encoding (RLE) / Uncompressed
Algorithm
Adaptive Run-Length Encoding (RLE)
Color Depth
32-bit (8-bit per channel RGB + 8-bit shared Exponent)
Developed by
Greg Ward (Lawrence Berkeley National Laboratory)
Released
1989
Magic Bytes
23 3F 52 41 44 49 41 4E 43 45
Browser Support Comparison
| Browser | JPX | Radiance |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
JPX
JPX Strengths
- Removes the color space limitations of baseline JP2, adding native support for CMYK, CIE Lab, and custom vendor color spaces
- Supports multiple codestreams in a single file, allowing for rich compositing and animation
- Enables fragmented files where image data and metadata can reside in separate physical files via data references
Limitations
- Extremely complex specification makes full software implementation rare, leading to compatibility issues
- Zero web browser support, rendering it unsuitable for public internet distribution
- Often overkill for standard imaging tasks where baseline JP2 or modern alternatives like AVIF suffice
Radiance
Radiance Strengths
- Universally supported by almost every 3D modeling software, renderer, and game engine in existence
- RGBE encoding offers a brilliant balance between High Dynamic Range capability and small file size (compared to 32-bit float OpenEXR)
- Simple, easy-to-parse ASCII header followed by straightforward RLE binary data
Limitations
- Does not support alpha transparency (no way to store an isolated light source with a transparent background)
- The shared exponent architecture can occasionally introduce banding or color artifacts in extreme edge cases compared to true 16-bit/32-bit floating-point formats like OpenEXR
- Zero native browser support for 2D viewing
When to choose which format
JPX
Use JPX when…
- Prepress & Commercial Printing (CMYK)
- Geospatial Data
- Archival Preservation
- Medical Imaging
Radiance
Use Radiance when…
- Image-Based Lighting (IBL)
- 3D Environment Maps (HDRI Skydomes)
- Lighting Simulation
- VFX and CGI Rendering