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Image MIME Reference
Epson-ERF

Epson Raw Format

image/x-epson-erf
VS

Khronos Texture 2.0

image/ktx2
KTX2

A complete technical comparison of Epson Raw Format 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 Epson-ERF KTX2
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support Yes Yes
EXIF Metadata Yes ✕ No
ICC Color Profile ✕ No ✕ No
Epson Raw Format
image/x-epson-erf
Extension
.erf
Container TIFF/EP
Compression Uncompressed / Lossless JPEG (ITU-T81)
Algorithm
NoneLossless JPEG
Color Depth 12-bit (Per Channel)
Developed by Seiko Epson Corporation
Released 2004
Magic Bytes
49 49 2A 00 or 4D 4D 00 2A
Full Epson-ERF reference →
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 →

Browser Support Comparison

Browser Epson-ERF KTX2
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
Epson-ERF

Epson-ERF Strengths

  • Preserves original raw sensor data, allowing extreme recovery of highlights and shadows compared to in-camera JPEGs
  • Utilizes the standard TIFF container structure, making it relatively easy for open-source software (like dcraw and LibRaw) to parse and decode
Limitations
  • Completely obsolete proprietary format tied to a defunct line of digital cameras
  • Requires parsing EXIF metadata to differentiate it from standard TIFF files programmatically
  • Cannot be natively viewed in web browsers or standard operating system image viewers without specialized codecs
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

Epson-ERF
Use Epson-ERF when…
  • Vintage Digital Photography (Epson R-D1)
  • Non-destructive Image Post-Processing
  • Raw Imaging Archival
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)

More comparisons

Epson-ERF vs ACES → KTX2 vs ACES → Epson-ERF vs APNG → KTX2 vs APNG → Epson-ERF vs AVCI → KTX2 vs AVCI → Epson-ERF vs AVCS → KTX2 vs AVCS → Epson-ERF vs AVIF → KTX2 vs AVIF → All comparisons →
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