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Image MIME Reference
DjVu

DjVu Document

image/vnd.djvu
VS

Flexible Image Transport System

image/fits
FITS

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

Equal browser support

Feature Support

Feature DjVu FITS
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
DjVu Document
image/vnd.djvu
Extension
.djvu.djv
Container Interchange File Format (IFF)
Compression JB2 (Bi-tonal Text) / IW44 (Wavelet Background) / BZZ (General Data/Text)
Algorithm
JB2IW44BZZ
Color Depth 1-bit (Foreground Text), 24-bit (Background)
Developed by AT&T Labs (Yann LeCun, Léon Bottou, Patrick Haffner, Paul G. Howard)
Released 1996
Magic Bytes
41 54 26 54 46 4F 52 4D
Full DjVu 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 DjVu FITS
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
DjVu

DjVu Strengths

  • Unmatched compression ratios for high-resolution scanned documents (often 5 to 10 times smaller than equivalent JPEG/TIFF-based PDFs)
  • Separates text layers cleanly from backgrounds, allowing for highly legible text even at low file sizes
  • Embedded OCR (Optical Character Recognition) text layers allow for fast searching
Limitations
  • Lacks native support in modern operating systems and web browsers, requiring third-party software
  • Largely superseded by PDF/A and modern PDF compression standards in standard corporate workflows
  • Not suitable for vector graphics or born-digital documents (like Word exports), where standard PDF is far superior
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

DjVu
Use DjVu when…
  • Scanned Books and Manuals
  • Digital Libraries (e.g., Internet Archive)
  • Historical Document Archiving
FITS
Use FITS when…
  • Astronomy & Astrophysics
  • Space Telescope Data (Hubble, JWST)
  • Scientific Data Archiving
  • Spectroscopy

More comparisons

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