Free webp to jpg
EN
Image MIME Reference
CNS-INF2

Comverse Network Systems INF2 Image

image/vnd.cns.inf2
VS

Progressive JPEG (Legacy IE Alias)

image/pjpeg
PJPEG

A complete technical comparison of Comverse Network Systems INF2 Image and Progressive JPEG (Legacy IE Alias) — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

PJPEG wins on browser support

Feature Support

Feature CNS-INF2 PJPEG
Transparency (Alpha) ✕ No ✕ No
Animation Support ✕ No ✕ No
Progressive Loading ✕ No Yes
HDR Support ✕ No ✕ No
EXIF Metadata ✕ No Yes
ICC Color Profile ✕ No Yes
Comverse Network Systems INF2 Image
image/vnd.cns.inf2
Extension
.inf2
Container Proprietary Comverse Container
Compression Proprietary
Algorithm
Unknown (Proprietary Telecom Encoding)
Color Depth Unknown
Developed by Comverse Network Systems (Ann McLaughlin)
Released 1999
Magic Bytes
Unknown (Proprietary)
Full CNS-INF2 reference →
Progressive JPEG (Legacy IE Alias)
image/pjpeg
Extension
.jpeg.jpg.pjpeg.pjp.jfif
Container JPEG (ISO/IEC 10918-1)
Compression Lossy (DCT)
Algorithm
Discrete Cosine Transform (DCT)
Color Depth 8-bit, 12-bit
Developed by Joint Photographic Experts Group / Microsoft (Alias)
Released 1992
Magic Bytes
FF D8 FF E0 (JFIF) / FF D8 FF E1 (Exif)
Full PJPEG reference →

Browser Support Comparison

Browser CNS-INF2 PJPEG
Chrome Chrome
✕
✓ All
Firefox Firefox
✕
✓ All
Safari Safari
✕
✓ All
Edge Edge
✕
✓ All
IE IE (Legacy)
✕
✓
CNS-INF2

CNS-INF2 Strengths

  • Historically allowed Comverse to standardize media transmission internally across their global telecom messaging platforms
Limitations
  • Completely obsolete and non-functional outside of decommissioned telecom infrastructure
  • Undocumented, closed-source binary structure
  • Zero support in modern image processing libraries like ImageMagick, libvips, or FFmpeg
PJPEG

PJPEG Strengths

  • Progressive JPEGs (which this MIME type attempted to describe) provide excellent perceived loading speeds on slow connections by rendering a low-resolution preview first
  • Files sent with this MIME type are fully backwards compatible with any standard JPEG decoder
Limitations
  • It is a non-standard MIME type that violates IANA specifications
  • Causes strict file upload validation scripts to fail if not explicitly whitelisted or mapped
  • Creates unnecessary confusion, as the official image/jpeg MIME type already fully encompasses progressive encoding

When to choose which format

CNS-INF2
Use CNS-INF2 when…
  • Legacy Telecom Infrastructure
  • Historical Comverse Unified Messaging Systems
  • Proprietary Server-to-Server Media Exchange
PJPEG
Use PJPEG when…
  • Legacy Internet Explorer File Uploads
  • Progressive Image Rendering (Historical context)

More comparisons

CNS-INF2 vs ACES → PJPEG vs ACES → CNS-INF2 vs APNG → PJPEG vs APNG → CNS-INF2 vs AVCI → PJPEG vs AVCI → CNS-INF2 vs AVCS → PJPEG vs AVCS → CNS-INF2 vs AVIF → PJPEG vs AVIF → All comparisons →
Share this comparison