Image MIME Reference
VTF
Valve Texture Format
image/vnd.valve.source.texture
VS
Pixologic ZBrush PCX
image/vnd.zbrush.pcx
ZBrush-PCX
A complete technical comparison of Valve Texture Format and Pixologic ZBrush PCX — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | VTF | ZBrush-PCX |
|---|---|---|
| Transparency (Alpha) | Yes | ✕ No |
| Animation Support | Yes | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
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
Pixologic ZBrush PCX
image/vnd.zbrush.pcx
Extension
.pcx
Container
ZSoft PCX
Compression
Run-Length Encoding (RLE)
Algorithm
ZSoft Run-Length Encoding (RLE)
Color Depth
8-bit (Grayscale), 24-bit (RGB)
Developed by
ZSoft (Format) / Pixologic (MIME Registration)
Released
1985
Magic Bytes
0A 05 01 08
Browser Support Comparison
| Browser | VTF | ZBrush-PCX |
|---|---|---|
Chrome
|
✕ | ✕ |
Firefox
|
✕ | ✕ |
Safari
|
✕ | ✕ |
Edge
|
✕ | ✕ |
IE (Legacy)
|
✕ | ✕ |
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
ZBrush-PCX
ZBrush-PCX Strengths
- Extremely simple, lossless RLE compression makes it trivial to parse and encode programmatically
- Universally supported by almost every 2D image editor created since the 1990s
Limitations
- Completely obsolete for modern 3D workflows, which require 16-bit or 32-bit floating-point precision (like OpenEXR or TIFF) to avoid stepping artifacts in displacement maps
- No support for modern metadata (EXIF/XMP) or native alpha channels
- Zero native support in modern web browsers
When to choose which format
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)
ZBrush-PCX
Use ZBrush-PCX when…
- Legacy ZBrush Alpha Brushes
- 8-bit Grayscale Displacement Maps
- ZBrush Texture Exports