Image MIME Reference
HEIC-Sequence
HEVC Image Sequence (HEIF Container)
image/heic-sequence
VS
Radiance HDR
image/vnd.radiance
Radiance
A complete technical comparison of HEVC Image Sequence (HEIF Container) and Radiance HDR — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
HEIC-Sequence wins on browser support
Feature Support
| Feature | HEIC-Sequence | Radiance |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
HEVC Image Sequence (HEIF Container)
image/heic-sequence
Extension
.heics.heic
Container
HEIF / ISOBMFF (ISO/IEC 14496-12)
Compression
Lossy / Lossless
Algorithm
HEVC (H.265)
Color Depth
8-bit, 10-bit, 12-bit, 16-bit
Developed by
Moving Picture Experts Group (MPEG) / Apple
Released
2017
Magic Bytes
XX XX XX XX 66 74 79 70 68 65 76 63
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 | HEIC-Sequence | Radiance |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✓ 11+
|
✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
HEIC-Sequence
HEIC-Sequence Strengths
- Incredibly efficient storage for bursts and short animations compared to GIF or motion JPEG
- Supports 16-bit color, HDR, and alpha channel transparency across all frames
- Shares frame data blocks, meaning the base image and animation data are heavily optimized for space
Limitations
- Zero support in web browsers outside the Apple ecosystem (Chrome, Firefox, Edge do not support it)
- Heavily encumbered by HEVC patent pools, hindering open-source adoption
- Complex container structure makes parsing and decoding difficult without specialized libraries
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
HEIC-Sequence
Use HEIC-Sequence when…
- Apple Live Photos
- Burst Photography
- High-Quality Animations
- Cinemagraphs
Radiance
Use Radiance when…
- Image-Based Lighting (IBL)
- 3D Environment Maps (HDRI Skydomes)
- Lighting Simulation
- VFX and CGI Rendering