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Image MIME Reference
AVIF

AV1 Image File Format

image/avif
VS

Flexible Image Transport System

image/fits
FITS

A complete technical comparison of AV1 Image File Format and Flexible Image Transport System — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

AVIF wins on browser support

Feature Support

Feature AVIF FITS
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
AV1 Image File Format
image/avif
Extension
.avif
Container HEIF / ISOBMFF
Compression AV1 Lossy / AV1 Lossless
Algorithm
AV1
Color Depth 8-bit, 10-bit, 12-bit
Developed by Alliance for Open Media (AOMedia)
Released 2019
Magic Bytes
XX XX XX XX 66 74 79 70 61 76 69 66
Full AVIF reference →
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 →

Browser Support Comparison

Browser AVIF FITS
Chrome Chrome
✓ 85+
 ✕
Firefox Firefox
✓ 93+
 ✕
Safari Safari
✓ 16+
 ✕
Edge Edge
✓ 121+
 ✕
IE IE (Legacy)
✕ ✕
AVIF

AVIF Strengths

  • Best-in-class compression — typically 20–50% smaller than WebP at equivalent quality
  • Native HDR and wide color gamut (BT.2020) support
  • Supports 8, 10, and 12-bit color depth
Limitations
  • Encoding is highly CPU-intensive — significantly slower than JPEG or WebP
  • Requires Edge 121+ (not supported in earlier Edge versions)
  • Limited support in native desktop image viewers
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

When to choose which format

AVIF
Use AVIF when…
  • Next-Gen Websites
  • HDR Photography
  • High-Quality Web Images
FITS
Use FITS when…
  • Astronomy & Astrophysics
  • Space Telescope Data (Hubble, JWST)
  • Scientific Data Archiving
  • Spectroscopy

More comparisons

AVIF vs ACES → FITS vs ACES → AVIF vs APNG → FITS vs APNG → AVIF vs AVCI → FITS vs AVCI → AVIF vs AVCS → FITS vs AVCS → All comparisons →
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