Image MIME Reference
JNG
JPEG Network Graphics
image/x-jng
VS
Khronos Texture 2.0
image/ktx2
KTX2
A complete technical comparison of JPEG Network Graphics and Khronos Texture 2.0 — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.
Equal browser support
Feature Support
| Feature | JNG | KTX2 |
|---|---|---|
| Transparency (Alpha) | Yes | Yes |
| Animation Support | ✕ No | ✕ No |
| Progressive Loading | Yes | ✕ No |
| HDR Support | ✕ No | Yes |
| EXIF Metadata | Yes | ✕ No |
| ICC Color Profile | Yes | ✕ No |
JPEG Network Graphics
image/x-jng
Extension
.jng
Container
PNG-style Chunk Structure (JHDR, JDAT, IDAT, IEND)
Compression
Lossy (JPEG/DCT for color) / Lossless (Deflate for alpha mask)
Algorithm
JPEG (Discrete Cosine Transform)Deflate (LZ77)
Color Depth
8-bit, 12-bit, 24-bit (RGB), 32-bit (RGBA)
Developed by
MNG Development Group (Glenn Randers-Pehrson et al.)
Released
2001
Magic Bytes
8B 4A 4E 47 0D 0A 1A 0A
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
Browser Support Comparison
| Browser | JNG | KTX2 |
|---|---|---|
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✕ | ✕ |
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✕ | ✕ |
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|
✕ | ✕ |
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|
✕ | ✕ |
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|
✕ | ✕ |
JNG
JNG Strengths
- Solved a massive technical hurdle in the early 2000s by combining high-compression lossy photographic data with crisp, 8-bit alpha transparency
- Utilized the highly robust, extensible chunk-based architecture of the PNG format
- Provided an excellent, bandwidth-saving alternative to massive 32-bit transparent PNGs for web design
Limitations
- Failed to achieve critical mass; browser vendors largely abandoned the MNG/JNG standard due to implementation complexity
- Completely obsolete today, having been superseded by natively supported, superior formats like WebP, AVIF, and HEIC
- Decoding requires a hybrid engine that can parse PNG chunks while simultaneously decoding a JPEG stream and a Deflate stream, complicating software support
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
When to choose which format
JNG
Use JNG when…
- Embedded frames in MNG animations
- Historical web graphics requiring lossy compression with transparency
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)