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Image MIME Reference
FITS

Flexible Image Transport System

image/fits
VS

Khronos Texture

image/ktx
KTX

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

Equal browser support

Feature Support

Feature FITS KTX
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
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 →
Khronos Texture
image/ktx
Extension
.ktx
Container KTX (Khronos Texture 1.1)
Compression Uncompressed / GPU Compressed (ASTC, ETC, BCn, PVRTC)
Algorithm
ASTCETC1 / ETC2BCn (DXT)PVRTCBasis Universal (in KTX2)
Color Depth 8-bit, 16-bit, 32-bit (Integer/Float)
Developed by Khronos Group
Released 2010
Magic Bytes
AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A
Full KTX reference →

Browser Support Comparison

Browser FITS KTX
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
KTX

KTX Strengths

  • Enables direct-to-GPU texture uploading, drastically reducing load times and CPU overhead in 3D applications
  • Supports complex texture types natively (mipmaps, cubemaps, 3D volumes, texture arrays)
  • Standardized across major Khronos APIs (OpenGL, Vulkan, WebGL) unlike vendor-specific formats like DDS
Limitations
  • Requires custom JavaScript loaders to parse and display on the web
  • Zero native support in consumer image viewers or 2D photo editing software
  • Format fragmentation: a KTX file containing an ASTC payload will fail to render on hardware that only supports BCn compression (KTX2 and Basis Universal solve this)

When to choose which format

FITS
Use FITS when…
  • Astronomy & Astrophysics
  • Space Telescope Data (Hubble, JWST)
  • Scientific Data Archiving
  • Spectroscopy
KTX
Use KTX when…
  • Real-time 3D Graphics
  • WebGL / WebGPU Applications
  • Mobile Games
  • Virtual/Augmented Reality (VR/AR)

More comparisons

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