Free webp to jpg
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Image MIME Reference
Net-FPX

Network FlashPix

image/vnd.net-fpx
VS

Portable Pixmap

image/x-portable-pixmap
PPM

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

Equal browser support

Feature Support

Feature Net-FPX PPM
Transparency (Alpha) Yes ✕ No
Animation Support ✕ No ✕ No
Progressive Loading Yes ✕ No
HDR Support ✕ No Yes
EXIF Metadata Yes ✕ No
ICC Color Profile Yes ✕ No
Network FlashPix
image/vnd.net-fpx
Extension
.fpx
Container Microsoft OLE Structured Storage (COM)
Compression JPEG (Lossy) / Uncompressed / Single-color (Solid)
Algorithm
JPEGNone
Color Depth 8-bit (Grayscale/Indexed), 24-bit (RGB), 32-bit (CMYK/RGBA)
Developed by Digital Imaging Group (Kodak, HP, Live Picture, Microsoft)
Released 1996
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1
Full Net-FPX 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 Net-FPX PPM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Net-FPX

Net-FPX Strengths

  • Revolutionized web imaging in the late 1990s by proving that massive gigapixel images could be navigated seamlessly over 56k dial-up modems
  • Pioneered the tile-based, multi-resolution pyramid concepts that eventually evolved into modern standards like IIIF (International Image Interoperability Framework)
Limitations
  • Completely obsolete, having been replaced by standard JPEG servers and modern tiling formats like Deep Zoom or JPEG 2000/XR
  • Relied on proprietary Java applets or ActiveX controls to render the tiles dynamically in a web browser
  • Extremely complex to parse server-side due to the heavy OLE filesystem container
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

Net-FPX
Use Net-FPX when…
  • Historical Internet Imaging Protocol (IIP) Streaming
  • Early E-Commerce Deep Zoom Implementations
  • Legacy High-Resolution Image 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

Net-FPX vs ACES → PPM vs ACES → Net-FPX vs APNG → PPM vs APNG → Net-FPX vs AVCI → PPM vs AVCI → Net-FPX vs AVCS → PPM vs AVCS → Net-FPX vs AVIF → PPM vs AVIF → All comparisons →
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