Image MIME Reference
EMF
Windows Enhanced Metafile
image/x-emf
VS
Network FlashPix
image/vnd.net-fpx
Net-FPX
A complete technical comparison of Windows Enhanced Metafile and Network FlashPix — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | EMF | Net-FPX |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | Yes |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | Yes |
| ICC Color Profile | Yes | Yes |
Windows Enhanced Metafile
image/x-emf
Extension
.emf
Container
Windows GDI/GDI+ Record Sequence
Compression
Uncompressed (Binary Drawing Records)
Algorithm
None
Color Depth
Vector (32-bit GDI/GDI+ Colors), Supports embedded 24-bit/32-bit bitmaps
Developed by
Microsoft Corporation
Released
1993
Magic Bytes
01 00 00 00 (Header Type) ... 20 45 4D 46 (Signature at offset 40)
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
Browser Support Comparison
| Browser | EMF | Net-FPX |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✓
|
✕ |
EMF
EMF Strengths
- Device independent, meaning it renders consistently across different monitors and printers regardless of resolution
- Fully supports 32-bit precision and advanced GDI+ drawing commands, including alpha transparency and anti-aliasing (EMF+)
- Native rendering within the Windows OS ensures fast performance and flawless fidelity in Microsoft Office applications
Limitations
- Heavily tied to the Windows Graphics Device Interface API, making it notoriously difficult to parse perfectly on macOS or Linux
- Completely unsupported by modern web standards; cannot be embedded in HTML without conversion to SVG
- Security history: Like WMF, malicious drawing records can theoretically exploit vulnerabilities in older GDI parsers
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
When to choose which format
EMF
Use EMF when…
- Microsoft Office Vector Graphics and Clip Art
- Windows Print Spooling (EMF Spool Files)
- High-fidelity Vector Interchange on Windows
Net-FPX
Use Net-FPX when…
- Historical Internet Imaging Protocol (IIP) Streaming
- Early E-Commerce Deep Zoom Implementations
- Legacy High-Resolution Image Servers