Image MIME Reference
PNM
Portable Anymap
image/x-portable-anymap
VS
Simple Vector Format
image/vnd.svf
SVF
A complete technical comparison of Portable Anymap and Simple Vector Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | PNM | SVF |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Portable Anymap
image/x-portable-anymap
Extension
.pnm
Container
Netpbm
Compression
Uncompressed
Algorithm
None
Color Depth
1-bit (PBM), 8-bit to 16-bit (PGM), 24-bit to 48-bit (PPM)
Developed by
Jef Poskanzer (Netpbm Project)
Released
1988
Magic Bytes
50 31, 50 32, 50 33, 50 34, 50 35, or 50 36
Simple Vector Format
image/vnd.svf
Extension
.svf
Container
Custom Binary/Text (Legacy) or ZIP (Autodesk Forge)
Compression
Uncompressed / Deflate (in modern Autodesk SVF implementations)
Algorithm
None
Color Depth
Vector Data (Not Applicable)
Developed by
SoftSource & NCSA (National Center for Supercomputing Applications)
Released
1995
Magic Bytes
Unknown (SoftSource SVF)
Browser Support Comparison
| Browser | PNM | SVF |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
PNM
PNM Strengths
- Unparalleled simplicity: parsers and writers for PNM files can be written from scratch in C or Python in just a few minutes without relying on external libraries
- Serves as an excellent foundational teaching tool for computer science students learning about image arrays and raster graphics
- Flawlessly pipes through Unix command-line utilities for robust automated image processing (via the Netpbm suite)
Limitations
- Zero compression natively results in astronomical file sizes, making it entirely impractical for web delivery or consumer storage
- No support for standard metadata formats like EXIF, XMP, or ICC color profiles
- No native alpha channel support in the classic PNM specification (though the newer PAM format 'P7' addresses this)
SVF
SVF Strengths
- Acted as a crucial pioneering stepping-stone in proving that scalable, zoomable vector graphics were viable and necessary for the World Wide Web
Limitations
- Completely obsolete and unsupported by modern web standards
- Required end-users to install bulky, proprietary browser plugins
- Causes significant developer confusion today due to Autodesk adopting the exact same acronym and file extension for a completely different technology
When to choose which format
PNM
Use PNM when…
- Unix/Linux Command-Line Image Processing (Netpbm suite)
- Academic Computer Vision Research
- Intermediary Format for Image Format Conversion
SVF
Use SVF when…
- Historical Web-based CAD Viewers (1990s)
- Legacy 2D Vector Archival
- Autodesk Platform Services (Forge) Model Translation (Name Collision)