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Image MIME Reference
FITS

Flexible Image Transport System

image/fits
VS

Sony Alpha Raw Image

image/x-sony-arw
Sony-ARW

A complete technical comparison of Flexible Image Transport System and Sony Alpha Raw Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature FITS Sony-ARW
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata ✕ No Yes
ICC Color Profile ✕ No Yes
Flexible Image Transport System
image/fits
Extension
.fits.fit.fts
Container FITS
Compression Uncompressed / Tile Compressed (Rice, GZIP)
Algorithm
UncompressedRiceGZIPHcompress
Color Depth 8-bit, 16-bit, 32-bit, 64-bit (Float/Double)
Developed by IAU FITS Working Group / NASA
Released 1981
Magic Bytes
53 49 4D 50 4C 45 20 20 3D 20
Full FITS reference →
Sony Alpha Raw Image
image/x-sony-arw
Extension
.arw
Container TIFF-based (Proprietary)
Compression Uncompressed / Lossless Compressed / Lossy Compressed
Algorithm
NoneSony Proprietary LosslessSony Proprietary Lossy
Color Depth 12-bit (Per Channel), 14-bit (Per Channel)
Developed by Sony Corporation
Released 2006
Magic Bytes
49 49 2A 00
Full Sony-ARW reference →

Browser Support Comparison

Browser FITS Sony-ARW
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
FITS

FITS Strengths

  • The undisputed global standard for archiving and sharing astronomical data
  • Self-documenting: Headers are written in plain ASCII, ensuring data is readable decades later regardless of software
  • Supports incredibly high dynamic range, N-dimensional arrays, and complex binary tables
Limitations
  • No support in standard consumer software or web browsers
  • Uncompressed raw FITS files from modern telescopes can be excessively large
  • Does not use standard metadata models like EXIF or XMP, requiring specialized parsers
Sony-ARW

Sony-ARW Strengths

  • Retains absolute maximum sensor data, enabling massive shadow recovery and highlight protection compared to compressed in-camera JPEGs
  • Embeds high-quality JPEG previews and robust metadata, allowing photographers to match in-camera color science (like Creative Looks) perfectly during raw processing
  • Utilizes the standard TIFF container structure, ensuring broad compatibility with open-source decoding libraries (like LibRaw)
Limitations
  • Proprietary format means it requires constant updates to raw processing engines every time Sony releases a new camera model
  • Sony's historically controversial lossy compression algorithm (often called 'star eater' due to spatial filtering artifacts) was a drawback for astrophotography in older ARW versions, though largely resolved in newer models with uncompressed/lossless options
  • Cannot be directly embedded into web pages or used in standard HTML/CSS contexts

When to choose which format

FITS
Use FITS when…
  • Astronomy & Astrophysics
  • Space Telescope Data (Hubble, JWST)
  • Scientific Data Archiving
  • Spectroscopy
Sony-ARW
Use Sony-ARW when…
  • Professional Digital Photography
  • Non-destructive Image Post-Processing
  • High Dynamic Range (HDR) Imaging Archival

More comparisons

FITS vs ACES → Sony-ARW vs ACES → FITS vs APNG → Sony-ARW vs APNG → FITS vs AVCI → Sony-ARW vs AVCI → FITS vs AVCS → Sony-ARW vs AVCS → FITS vs AVIF → Sony-ARW vs AVIF → All comparisons →
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