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Image MIME Reference
AZV

AirZip Accelerator Image

image/vnd.airzip.accelerator.azv
VS

Portable Pixmap

image/x-portable-pixmap
PPM

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

Equal browser support

Feature Support

Feature AZV PPM
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support ✕ No Yes
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 →
Portable Pixmap
image/x-portable-pixmap
Extension
.ppm
Container Netpbm
Compression Uncompressed
Algorithm
None
Color Depth 24-bit (RGB), 48-bit (RGB High Color)
Developed by Jef Poskanzer (Netpbm Project)
Released 1988
Magic Bytes
50 33 (ASCII) or 50 36 (Binary)
Full PPM reference →

Browser Support Comparison

Browser AZV PPM
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
PPM

PPM Strengths

  • Absolute structural simplicity allows parsers and renderers (such as custom raytracers) to write directly to the format with virtually no overhead or external libraries
  • Supports 16-bit per channel (48-bit total) precision, preserving deep color accuracy before converting to final delivery formats
  • ASCII encoding ('P3') allows manual editing and visual inspection of RGB values directly within a text editor
Limitations
  • Zero compression results in astronomical file sizes, making it entirely impractical for web delivery or consumer storage
  • Does not natively support an alpha channel for transparency (this is handled by the newer PAM extension format within the Netpbm suite)
  • Lacks support for modern metadata standards like EXIF, XMP, or embedded ICC color profiles

When to choose which format

AZV
Use AZV when…
  • Dial-up Web Acceleration
  • Bandwidth Optimization (Historical)
  • Legacy Proxy Servers
PPM
Use PPM when…
  • Intermediary Format for Image Format Conversion
  • Academic Computer Graphics and Raytracing Output
  • Unix/Linux Command-Line Image Pipelines

More comparisons

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