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Image MIME Reference
AZV

AirZip Accelerator Image

image/vnd.airzip.accelerator.azv
VS

DjVu Document

image/vnd.djvu
DjVu

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

Equal browser support

Feature Support

Feature AZV DjVu
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading Yes Yes
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
AirZip Accelerator Image
image/vnd.airzip.accelerator.azv
Extension
.azv
Container Proprietary AirZip Container
Compression Lossy (Proprietary) / Lossless (Proprietary)
Algorithm
AirZip Proprietary Compression
Color Depth 8-bit (Indexed), 24-bit (RGB)
Developed by AirZip, Inc.
Released 1999
Magic Bytes
Unknown (Proprietary)
Full AZV reference →
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 →

Browser Support Comparison

Browser AZV DjVu
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
AZV

AZV Strengths

  • Historically allowed internet users to browse the web up to 5x faster over 56k dial-up modems by drastically reducing image payload sizes
  • Officially registered in the IANA vendor tree, preventing MIME type conflicts on early web proxy servers
Limitations
  • Completely obsolete in the modern broadband era
  • Closed-source and proprietary, meaning no modern image manipulation libraries (like ImageMagick or libvips) can decode it
  • Zero support in standard web browsers
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  • Largely superseded by PDF/A and modern PDF compression standards in standard corporate workflows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

When to choose which format

AZV
Use AZV when…
  • Dial-up Web Acceleration
  • Bandwidth Optimization (Historical)
  • Legacy Proxy Servers
DjVu
Use DjVu when…
  • Scanned Books and Manuals
  • Digital Libraries (e.g., Internet Archive)
  • Historical Document Archiving

More comparisons

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