Image MIME Reference
KTX2
Khronos Texture 2.0
image/ktx2
VS
Silicon Graphics Image
image/sgi
SGI
A complete technical comparison of Khronos Texture 2.0 and Silicon Graphics Image — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | KTX2 | SGI |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | ✕ No | ✕ No |
| HDR Support | Yes | ✕ No |
| EXIF Metadata | ✕ No | ✕ No |
| ICC Color Profile | ✕ No | ✕ No |
Khronos Texture 2.0
image/ktx2
Extension
.ktx2
Container
KTX 2.0
Compression
Basis Universal (ETC1S / UASTC) / Zstandard (zstd) Supercompression / Uncompressed
Algorithm
ETC1SUASTCZstandard (zstd)Raw GPU Formats (ASTC, BCn)
Color Depth
8-bit, 16-bit, 32-bit (Float)
Developed by
Khronos Group
Released
2021
Magic Bytes
AB 4B 54 58 20 32 30 BB 0D 0A 1A 0A
Silicon Graphics Image
image/sgi
Extension
.sgi.rgb.rgba.bw.int.inta
Container
SGI Image Format
Compression
Uncompressed / Lossless (Run-Length Encoding)
Algorithm
RLENone
Color Depth
8-bit, 16-bit (Per Channel)
Developed by
Paul Haeberli (Silicon Graphics)
Released
1990
Magic Bytes
01 DA
Browser Support Comparison
| Browser | KTX2 | SGI |
|---|---|---|
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
|
|
✕ | ✕ |
KTX2
KTX2 Strengths
- Universal hardware compatibility: write once, transcode anywhere to the target GPU's preferred format (ASTC, BC7, PVRTC, etc.)
- Drastically reduces transmission size over networks thanks to Basis Universal and Zstandard supercompression
- Seamless integration with the glTF ecosystem for optimized 3D asset delivery
Limitations
- Requires WebAssembly (Wasm) decoders and JavaScript loaders for web viewing, increasing initial application payload slightly
- Encoding textures into high-quality Basis Universal UASTC can be computationally intensive and slow
- Zero support in traditional 2D image viewers or native OS previews
SGI
SGI Strengths
- Pioneered multi-channel and 16-bit per channel imaging capabilities required for high-end 1990s visual effects
- Extremely robust and simple header structure
- Reliable Run-Length Encoding provided solid lossless compression for flat-shaded 3D renders
Limitations
- Completely obsolete for modern web and application development
- Zero native web browser compatibility
- Largely replaced by TIFF and OpenEXR in modern professional VFX and 3D pipelines
When to choose which format
KTX2
Use KTX2 when…
- glTF 3D Models (KHR_texture_basisu)
- WebGPU and WebGL Applications
- Game Engines (Unity, Unreal, Godot)
- Augmented and Virtual Reality (AR/VR)
SGI
Use SGI when…
- Legacy 3D Animation & VFX
- Silicon Graphics IRIX Workflows
- Historical CGI Archiving