Image MIME Reference
FACTI
BlockFact Image
image/vnd.blockfact.facti
VS
Portable Pixmap
image/x-portable-pixmap
PPM
A complete technical comparison of BlockFact Image and Portable Pixmap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | FACTI | PPM |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
BlockFact Image
image/vnd.blockfact.facti
Extension
.facti
Container
BlockFact Authenticated Container
Compression
Container (Inherits payload compression, e.g., JPEG/PNG)
Algorithm
None (Pass-through to embedded payload)
Color Depth
Inherited from payload
Developed by
BlockFact
Released
2025
Magic Bytes
Unknown (Proprietary Container)
Portable Pixmap
image/x-portable-pixmap
Extension
.ppm
Container
Netpbm
Compression
Uncompressed
Algorithm
None
Color Depth
24-bit (RGB), 48-bit (RGB High Color)
Developed by
Jef Poskanzer (Netpbm Project)
Released
1988
Magic Bytes
50 33 (ASCII) or 50 36 (Binary)
Browser Support Comparison
| Browser | FACTI | PPM |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
FACTI
FACTI Strengths
- Provides undeniable, mathematically verifiable proof of a photo's origin (time, location, and device) via the StarkNet blockchain [1.3.1]
- Privacy-first design utilizes zero-knowledge proofs (Groth16), meaning the actual image is never uploaded to a central server or blockchain
- Invisible watermarking ensures that even if the image is screenshotted or cropped, tampering can be detected
Limitations
- Lacks native rendering support in web browsers and standard image viewers, requiring specialized software to view
- Requires blockchain registration at the moment of capture, making it incompatible with existing legacy photos
- The proprietary nature of the container limits integration to environments supporting the BlockFact SDK
PPM
PPM Strengths
- Absolute structural simplicity allows parsers and renderers (such as custom raytracers) to write directly to the format with virtually no overhead or external libraries
- Supports 16-bit per channel (48-bit total) precision, preserving deep color accuracy before converting to final delivery formats
- ASCII encoding ('P3') allows manual editing and visual inspection of RGB values directly within a text editor
Limitations
- Zero compression results in astronomical file sizes, making it entirely impractical for web delivery or consumer storage
- Does not natively support an alpha channel for transparency (this is handled by the newer PAM extension format within the Netpbm suite)
- Lacks support for modern metadata standards like EXIF, XMP, or embedded ICC color profiles
When to choose which format
FACTI
Use FACTI when…
- Journalism and Media Authentication
- Legal and Insurance Evidence
- AI Deepfake Prevention
- Content Provenance and Authorship
PPM
Use PPM when…
- Intermediary Format for Image Format Conversion
- Academic Computer Graphics and Raytracing Output
- Unix/Linux Command-Line Image Pipelines