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Image MIME Reference
Fuji-RAF

Fujifilm RAW Image

image/x-fuji-raf
VS

Progressive JPEG (Legacy IE Alias)

image/pjpeg
PJPEG

A complete technical comparison of Fujifilm RAW Image and Progressive JPEG (Legacy IE Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PJPEG wins on browser support

Feature Support

Feature Fuji-RAF PJPEG
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support Yes ✕ No
EXIF Metadata Yes Yes
ICC Color Profile Yes Yes
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
Full Fuji-RAF reference →
Progressive JPEG (Legacy IE Alias)
image/pjpeg
Extension
.jpeg.jpg.pjpeg.pjp.jfif
Container JPEG (ISO/IEC 10918-1)
Compression Lossy (DCT)
Algorithm
Discrete Cosine Transform (DCT)
Color Depth 8-bit, 12-bit
Developed by Joint Photographic Experts Group / Microsoft (Alias)
Released 1992
Magic Bytes
FF D8 FF E0 (JFIF) / FF D8 FF E1 (Exif)
Full PJPEG reference →

Browser Support Comparison

Browser Fuji-RAF PJPEG
Chrome Chrome
✕
✓ All
Firefox Firefox
✕
✓ All
Safari Safari
✕
✓ All
Edge Edge
✕
✓ All
IE IE (Legacy)
✕
✓
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
PJPEG

PJPEG Strengths

  • Progressive JPEGs (which this MIME type attempted to describe) provide excellent perceived loading speeds on slow connections by rendering a low-resolution preview first
  • Files sent with this MIME type are fully backwards compatible with any standard JPEG decoder
Limitations
  • It is a non-standard MIME type that violates IANA specifications
  • Causes strict file upload validation scripts to fail if not explicitly whitelisted or mapped
  • Creates unnecessary confusion, as the official image/jpeg MIME type already fully encompasses progressive encoding

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
PJPEG
Use PJPEG when…
  • Legacy Internet Explorer File Uploads
  • Progressive Image Rendering (Historical context)

More comparisons

Fuji-RAF vs ACES → PJPEG vs ACES → Fuji-RAF vs APNG → PJPEG vs APNG → Fuji-RAF vs AVCI → PJPEG vs AVCI → Fuji-RAF vs AVCS → PJPEG vs AVCS → Fuji-RAF vs AVIF → PJPEG vs AVIF → All comparisons →
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