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Image MIME Reference
Olympus-ORF

Olympus Raw Format

image/x-olympus-orf
VS

Portable Pixmap

image/x-portable-pixmap
PPM

A complete technical comparison of Olympus Raw Format and Portable Pixmap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature Olympus-ORF PPM
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
Olympus Raw Format
image/x-olympus-orf
Extension
.orf
Container TIFF-based (with proprietary variants)
Compression Uncompressed / Proprietary Lossless
Algorithm
NoneOlympus Proprietary Lossless
Color Depth 12-bit (Per Channel)
Developed by Olympus Corporation (Now OM Digital Solutions)
Released 2000
Magic Bytes
49 49 52 4F (IIRO) or 4D 4D 4F 52 (MMOR) or 49 49 53 52 (IIRS)
Full Olympus-ORF reference →
Portable Pixmap
image/x-portable-pixmap
Extension
.ppm
Container Netpbm
Compression Uncompressed
Algorithm
None
Color Depth 24-bit (RGB), 48-bit (RGB High Color)
Developed by Jef Poskanzer (Netpbm Project)
Released 1988
Magic Bytes
50 33 (ASCII) or 50 36 (Binary)
Full PPM reference →

Browser Support Comparison

Browser Olympus-ORF PPM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Olympus-ORF

Olympus-ORF Strengths

  • Retains maximum sensor data, allowing extreme recovery of highlights and shadows that would be permanently lost in a JPEG
  • White balance, sharpening, and color profiling are saved as metadata instructions, meaning they can be completely altered in post-production
  • Unique magic byte signatures make programmatic file sniffing highly reliable compared to other camera manufacturers' TIFF-spoofing headers
Limitations
  • Proprietary format means it requires constant updates to raw processing engines every time a new camera model is released
  • Produces very large file sizes (often 15MB to 30MB+ per image depending on sensor resolution)
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts
PPM

PPM Strengths

  • Absolute structural simplicity allows parsers and renderers (such as custom raytracers) to write directly to the format with virtually no overhead or external libraries
  • Supports 16-bit per channel (48-bit total) precision, preserving deep color accuracy before converting to final delivery formats
  • ASCII encoding ('P3') allows manual editing and visual inspection of RGB values directly within a text editor
Limitations
  • Zero compression results in astronomical file sizes, making it entirely impractical for web delivery or consumer storage
  • Does not natively support an alpha channel for transparency (this is handled by the newer PAM extension format within the Netpbm suite)
  • Lacks support for modern metadata standards like EXIF, XMP, or embedded ICC color profiles

When to choose which format

Olympus-ORF
Use Olympus-ORF when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Imaging Archival
PPM
Use PPM when…
  • Intermediary Format for Image Format Conversion
  • Academic Computer Graphics and Raytracing Output
  • Unix/Linux Command-Line Image Pipelines

More comparisons

Olympus-ORF vs ACES → PPM vs ACES → Olympus-ORF vs APNG → PPM vs APNG → Olympus-ORF vs AVCI → PPM vs AVCI → Olympus-ORF vs AVCS → PPM vs AVCS → Olympus-ORF vs AVIF → PPM vs AVIF → All comparisons →
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