Image MIME Reference
Alias-PIX
Alias PIX Image
image/x-alias-pix
VS
Digital Picture Exchange
image/dpx
DPX
A complete technical comparison of Alias PIX Image and Digital Picture Exchange — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | Alias-PIX | DPX |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| 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)
Digital Picture Exchange
image/dpx
Extension
.dpx
Container
DPX (SMPTE ST 268)
Compression
Uncompressed / RLE (Rarely used)
Algorithm
Uncompressed
Color Depth
8-bit, 10-bit, 12-bit, 16-bit, 32-bit (Float)
Developed by
SMPTE (Society of Motion Picture and Television Engineers)
Released
1994
Magic Bytes
53 44 50 58 (Big-endian) / 58 50 44 53 (Little-endian)
Browser Support Comparison
| Browser | Alias-PIX | DPX |
|---|---|---|
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- Completely obsolete, having been replaced by more robust formats like TIFF, TGA, and EXR in modern 3D pipelines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
DPX
DPX Strengths
- Industry standard for transferring uncompressed, high-fidelity film and VFX data
- Rich industry-specific metadata including timecode, keykode, and film stock information
- Supports logarithmic color spaces (LogC, Cineon) to preserve the massive dynamic range of film negatives
Limitations
- Massive file sizes (e.g., a single 4K 10-bit frame is ~50MB, resulting in ~1.2GB per second at 24fps)
- Zero native support in web browsers or consumer OS image viewers
- Requires heavy-duty, fast storage infrastructure (RAID/NVMe) to playback in real-time
When to choose which format
Alias-PIX
Use Alias-PIX when…
- Legacy Alias PowerAnimator Textures
- 1990s SGI Workstation Render Outputs
- Historical 3D Graphics Archival
DPX
Use DPX when…
- Film Scanning
- Visual Effects (VFX)
- Digital Intermediate (DI)
- Color Grading
- Archival