Image MIME Reference
Alias-PIX
Alias PIX Image
image/x-alias-pix
VS
RealNetworks RealFlash
image/vnd.rn-realflash
RealFlash
A complete technical comparison of Alias PIX Image and RealNetworks RealFlash — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Alias-PIX | RealFlash |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | Yes |
| HDR Support | ✕ No | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Alias PIX Image
image/x-alias-pix
Extension
.pix.als.alias.img
Container
Alias PIX Header
Compression
Run-Length Encoding (RLE)
Algorithm
RLE
Color Depth
24-bit (RGB), 8-bit (Matte/Grayscale variant)
Developed by
Alias Research (Later Alias|Wavefront / Autodesk)
Released
Early 1990s
Magic Bytes
No explicit magic bytes (Relies on 10-byte integer header)
RealNetworks RealFlash
image/vnd.rn-realflash
Extension
Container
RealMedia / SWF
Compression
Vector (Flash) / RealAudio Compression
Algorithm
Macromedia Vector CompressionDeflate (Zlib)
Color Depth
8-bit, 24-bit, 32-bit
Developed by
RealNetworks & Macromedia
Released
1997
Magic Bytes
46 57 53 (FWS - Standard Flash) or 2E 52 4D 46 (.RMF - RealMedia Container)
Browser Support Comparison
| Browser | Alias-PIX | RealFlash |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
Alias-PIX
Alias-PIX Strengths
- The highly simplified structure made it incredibly fast to encode and decode on early 1990s SGI hardware
- Lossless Run-Length Encoding (RLE) saved disk space without degrading the quality of final 3D renders
Limitations
- Completely obsolete, having been replaced by more robust formats like TIFF, TGA, and EXR in modern 3D pipelines
- The lack of a distinct magic byte signature makes reliable automated file detection almost impossible
- Does not support integrated alpha channels, instead requiring cumbersome, separate 'Matte' files to denote transparency
RealFlash
RealFlash Strengths
- Allowed complex, interactive vector animations to stream smoothly over 28.8k dial-up modems
- Perfectly synchronized streaming audio with timeline-based animations, which was revolutionary in 1997
Limitations
- Heavily reliant on proprietary browser plugins (RealPlayer), which were notoriously bloated
- Completely obsolete and unsupported on the modern web
- Tightly coupled server-client architecture required expensive RealServer licenses to host
When to choose which format
Alias-PIX
Use Alias-PIX when…
- Legacy Alias PowerAnimator Textures
- 1990s SGI Workstation Render Outputs
- Historical 3D Graphics Archival
RealFlash
Use RealFlash when…
- Historical Dial-up Web Animation
- Late-1990s Interactive Music Videos
- Streaming Vector Graphics