Image MIME Reference
FPX
FlashPix
image/vnd.fpx
VS
RealNetworks RealPix
image/vnd.rn-realpix
RealPix
A complete technical comparison of FlashPix and RealNetworks RealPix — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FPX | RealPix |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | Yes |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
FlashPix
image/vnd.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
Eastman Kodak, Microsoft, Hewlett-Packard, Live Picture
Released
1996
Magic Bytes
D0 CF 11 E0 A1 B1 1A E1
RealNetworks RealPix
image/vnd.rn-realpix
Extension
.rp
Container
IMFL (XML Markup)
Compression
Uncompressed (Plain Text Markup)
Algorithm
None (Plain Text)
Color Depth
Dependent on referenced images
Developed by
RealNetworks
Released
1998
Magic Bytes
3C 69 6D 66 6C
Browser Support Comparison
| Browser | FPX | RealPix |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
FPX
FPX Strengths
- Allowed early, low-RAM computers to view and edit massive, high-resolution digital photos instantly by only loading the needed tiles and resolutions
- Pioneered the multi-resolution pyramid and tiling concepts heavily used today in modern deep-zoom and web mapping applications (like Google Maps)
Limitations
- Completely obsolete and unsupported by modern web browsers or operating systems
- Uses the complex, proprietary Microsoft OLE container format, making it incredibly difficult to parse or extract data from without dedicated legacy libraries
- Prone to being misidentified by MIME sniffers as an old Microsoft Office document
RealPix
RealPix Strengths
- Allowed for 'Ken Burns'-style animated slideshows at a fraction of the bandwidth required for actual video, crucial for 1990s dial-up connections
- Plain text XML architecture made it easy for developers and hobbyists to hand-code complex multimedia presentations
- Perfectly synchronized with RealAudio streams using SMIL-like timing parameters
Limitations
- Completely obsolete and heavily reliant on the proprietary, defunct RealPlayer browser plugin
- Not a true image format, causing confusion when handled by standard image processing libraries which expect binary pixel data
- Lacks modern CSS or HTML5 canvas equivalents without completely rewriting the presentation logic
When to choose which format
FPX
Use FPX when…
- Legacy Digital Photography
- Kodak Picture CDs (Historical)
- Early High-Resolution Image Viewers
RealPix
Use RealPix when…
- Historical Dial-up Streaming Presentations
- RealPlayer Slideshows
- Bandwidth-efficient 'Video' Alternatives (late 1990s)