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Image MIME Reference
KTX2

Khronos Texture 2.0

image/ktx2
VS

Portable Bitmap

image/x-portable-bitmap
PBM

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

Equal browser support

Feature Support

Feature KTX2 PBM
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 Bitmap
image/x-portable-bitmap
Extension
.pbm
Container Netpbm
Compression Uncompressed
Algorithm
None
Color Depth 1-bit (Monochrome)
Developed by Jef Poskanzer (Netpbm Project)
Released 1988
Magic Bytes
50 31 (ASCII) or 50 34 (Binary)
Full PBM reference →

Browser Support Comparison

Browser KTX2 PBM
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
PBM

PBM Strengths

  • Absolute structural simplicity allows parsers to be written from scratch with just a few lines of code
  • ASCII encoding allows manual editing and debugging directly within a standard text editor
  • Serves as a flawless, lossless intermediary for 1-bit raster data like scanned documents or barcodes
Limitations
  • Strictly limited to 1-bit monochrome images; cannot natively display shades of gray or color
  • Lack of compression results in extremely large file sizes, particularly when using the ASCII 'P1' encoding
  • No support for alpha transparency or modern metadata standards like EXIF

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)
PBM
Use PBM when…
  • Optical Character Recognition (OCR) Pre-processing
  • Unix/Linux Command-Line Image Pipelines
  • Academic Image Processing Teaching

More comparisons

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