Image MIME Reference
Fuji-RAF
Fujifilm RAW Image
image/x-fuji-raf
VS
JPEG-LS
image/jls
JPEG-LS
A complete technical comparison of Fujifilm RAW Image and JPEG-LS — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Fuji-RAF | JPEG-LS |
|---|---|---|
| Transparency (Alpha) | ✕ No | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
Fujifilm RAW Image
image/x-fuji-raf
Extension
.raf
Container
Proprietary RAF Container
Compression
Uncompressed / Lossless Compressed / Lossy Compressed (Modern firmware)
Algorithm
NoneProprietary LosslessProprietary Lossy
Color Depth
14-bit (Per Channel - X-Series), 16-bit (Per Channel - GFX Series)
Developed by
Fujifilm Corporation
Released
2000
Magic Bytes
46 55 4A 49 46 49 4C 4D 43 43 44 2D 52 41 57 20
JPEG-LS
image/jls
Extension
.jls.jl
Container
JPEG Bitstream
Compression
Lossless / Near-Lossless (Predictive Coding)
Algorithm
LOCO-I (Low Complexity Lossless Compression for Images)Golomb-Rice Coding
Color Depth
8-bit, 12-bit, 16-bit (Per Channel)
Developed by
Joint Photographic Experts Group (ISO/ITU-T) & HP Labs
Released
1999
Magic Bytes
FF D8 FF F7
Browser Support Comparison
| Browser | Fuji-RAF | JPEG-LS |
|---|---|---|
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✕ | ✕ |
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✕ | ✕ |
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✕ | ✕ |
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✕ | ✕ |
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✕ | ✕ |
Fuji-RAF
Fuji-RAF Strengths
- Retains absolute maximum sensor data, enabling massive shadow recovery and highlight protection compared to compressed in-camera JPEGs
- Stores proprietary Fujifilm Film Simulation metadata (like Classic Chrome or Acros), allowing editors to perfectly replicate in-camera aesthetics
- Very distinct and reliable magic header makes programmatic file detection foolproof
Limitations
- Proprietary format requires continuous updates to third-party software (like Lightroom) whenever Fujifilm releases a new camera
- The X-Trans sensor matrix requires highly specialized demosaicing algorithms that are extremely computationally expensive, leading to slower import and rendering times
- Completely unsupported in standard web browsers and basic operating system image viewers
JPEG-LS
JPEG-LS Strengths
- Provides state-of-the-art lossless compression ratios for continuous-tone images, often outperforming Lossless JPEG and JPEG 2000
- Extremely fast and computationally inexpensive to encode/decode, requiring no complex floating-point math or DCTs
- Highly resilient in constrained hardware environments, making it ideal for medical equipment and deep-space probes (e.g., Mars rovers)
Limitations
- Zero native support in web browsers or standard consumer operating systems
- Lacks the advanced resolution scalability and progressive decoding features found in JPEG 2000
- Primarily relegated to niche enterprise sectors (healthcare/DICOM and aerospace) rather than consumer adoption
When to choose which format
Fuji-RAF
Use Fuji-RAF when…
- Professional Digital Photography
- Fujifilm X-Trans Sensor Image Archival
- High Dynamic Range (HDR) Post-Processing
JPEG-LS
Use JPEG-LS when…
- Medical Imaging (DICOM Encapsulation)
- Space and Planetary Imaging (NASA/ESA)
- Industrial Machine Vision
- Scientific Archival Storage