Image MIME Reference
Radiance
Radiance HDR
image/vnd.radiance
VS
WebP Image
image/webp
WebP
A complete technical comparison of Radiance HDR and WebP Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
WebP wins on browser support
Feature Support
| Feature | Radiance | WebP |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | ✕ No | Yes |
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
WebP Image
image/webp
Extension
.webp
Container
RIFF
Compression
Lossy / Lossless
Algorithm
VP8VP8L
Color Depth
8-bit
Developed by
Google
Released
2010
Magic Bytes
52 49 46 46 XX XX XX XX 57 45 42 50
Browser Support Comparison
| Browser | Radiance | WebP |
|---|---|---|
Chrome
|
✕ |
✓ 32+
|
Firefox
|
✕ |
✓ 65+
|
Safari
|
✕ |
✓ 14+
|
Edge
|
✕ |
✓ 18+
|
IE (Legacy)
|
✕ | ✕ |
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
WebP
WebP Strengths
- Superior lossy compression — 25–35% smaller than JPEG at equivalent quality
- Supports both animation and full alpha transparency
- Lossless mode available with smaller file sizes than PNG
Limitations
- Slower encoding than JPEG, especially for lossless
- Not supported in Internet Explorer or very old browsers
When to choose which format
Radiance
Use Radiance when…
- Image-Based Lighting (IBL)
- 3D Environment Maps (HDRI Skydomes)
- Lighting Simulation
- VFX and CGI Rendering
WebP
Use WebP when…
- Websites
- Ecommerce
- Mobile Apps
- CMS Images