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Image MIME Reference
KTX2

Khronos Texture 2.0

image/ktx2
VS

Portable Anymap

image/x-portable-anymap
PNM

A complete technical comparison of Khronos Texture 2.0 and Portable Anymap — covering compression, feature support, browser compatibility, magic bytes, and when to choose each format.

Equal browser support

Feature Support

Feature KTX2 PNM
Transparency (Alpha) Yes ✕ No
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
Full KTX2 reference →
Portable Anymap
image/x-portable-anymap
Extension
.pnm
Container Netpbm
Compression Uncompressed
Algorithm
None
Color Depth 1-bit (PBM), 8-bit to 16-bit (PGM), 24-bit to 48-bit (PPM)
Developed by Jef Poskanzer (Netpbm Project)
Released 1988
Magic Bytes
50 31, 50 32, 50 33, 50 34, 50 35, or 50 36
Full PNM reference →

Browser Support Comparison

Browser KTX2 PNM
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
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
PNM

PNM Strengths

  • Unparalleled simplicity: parsers and writers for PNM files can be written from scratch in C or Python in just a few minutes without relying on external libraries
  • Serves as an excellent foundational teaching tool for computer science students learning about image arrays and raster graphics
  • Flawlessly pipes through Unix command-line utilities for robust automated image processing (via the Netpbm suite)
Limitations
  • Zero compression natively results in astronomical file sizes, making it entirely impractical for web delivery or consumer storage
  • No support for standard metadata formats like EXIF, XMP, or ICC color profiles
  • No native alpha channel support in the classic PNM specification (though the newer PAM format 'P7' addresses this)

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)
PNM
Use PNM when…
  • Unix/Linux Command-Line Image Processing (Netpbm suite)
  • Academic Computer Vision Research
  • Intermediary Format for Image Format Conversion

More comparisons

KTX2 vs ACES → PNM vs ACES → KTX2 vs APNG → PNM vs APNG → KTX2 vs AVCI → PNM vs AVCI → KTX2 vs AVCS → PNM vs AVCS → KTX2 vs AVIF → PNM vs AVIF → All comparisons →
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