Image MIME Reference
PTI
PTI Image (Personal/Vanity Tree)
image/prs.pti
VS
Valve Texture Format
image/vnd.valve.source.texture
VTF
A complete technical comparison of PTI Image (Personal/Vanity Tree) and Valve Texture Format — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | PTI | VTF |
|---|---|---|
| Transparency (Alpha) | ✕ No | Yes |
| Animation Support | ✕ No | Yes |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
PTI Image (Personal/Vanity Tree)
image/prs.pti
Extension
.pti
Container
Proprietary
Compression
Unknown / Proprietary
Algorithm
Unknown
Color Depth
Unknown
Developed by
Jürn Laun
Released
1999
Magic Bytes
Unknown
Valve Texture Format
image/vnd.valve.source.texture
Extension
.vtf
Container
Valve Texture Format Header
Compression
DXTC (DXT1, DXT3, DXT5) / Uncompressed (BGRA8888, RGB888, etc.)
Algorithm
DXT1-DXT5None
Color Depth
8-bit, 24-bit (RGB), 32-bit (RGBA), 16-bit Floating Point (HDR)
Developed by
Valve Corporation
Released
2004
Magic Bytes
56 54 46 00
Browser Support Comparison
| Browser | PTI | VTF |
|---|---|---|
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
PTI
PTI Strengths
- Provided a registered MIME type namespace for a specific application's proprietary image format without conflicting with standard web types
Limitations
- Completely undocumented and unsupported in modern ecosystems
- Zero web browser compatibility
- Falls into the 'vanity' tree, making it irrelevant for standard cross-platform data exchange
VTF
VTF Strengths
- Extremely fast loading within the Source Engine because the block-compressed data goes directly into the GPU's VRAM without CPU decompression overhead
- Bundles mipmaps, volumetric slices, cubemap faces, and animation frames entirely within a single file
- Openly documented by the Valve Developer Community, leading to a massive ecosystem of third-party modding tools
Limitations
- Strictly tied to the Source Engine ecosystem; entirely useless in standard web or print contexts
- No native support in standard image editors without hunting down and installing specialized plugins
- Block compression algorithms (DXT) are lossy and can cause visible artifacting, especially on normal maps or smooth gradients
When to choose which format
PTI
Use PTI when…
- Legacy Application Specific Workflows
- Proprietary Image Storage
VTF
Use VTF when…
- Source Engine Game Textures
- Custom Maps and Modding (Garry's Mod, CS:GO)
- Animated In-Game Decals and Sprays
- Environment Cubemaps (Skyboxes)