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Image MIME Reference
IEF

Image Exchange Format

image/ief
VS

Khronos Texture

image/ktx
KTX

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

Equal browser support

Feature Support

Feature IEF KTX
Transparency (Alpha) ✕ No Yes
Animation Support ✕ No ✕ No
Progressive Loading ✕ No ✕ No
HDR Support ✕ No Yes
EXIF Metadata ✕ No ✕ No
ICC Color Profile ✕ No ✕ No
Image Exchange Format
image/ief
Extension
.ief
Container TIFF Class B (TIFF-B)
Compression Lossless (MH, MR, MMR) / Uncompressed
Algorithm
MHMRMMRUncompressed
Color Depth 1-bit (Monochrome)
Developed by IETF Network Fax Working Group
Released 1992
Magic Bytes
49 49 2A 00 (Little-endian) / 4D 4D 00 2A (Big-endian)
Full IEF reference →
Khronos Texture
image/ktx
Extension
.ktx
Container KTX (Khronos Texture 1.1)
Compression Uncompressed / GPU Compressed (ASTC, ETC, BCn, PVRTC)
Algorithm
ASTCETC1 / ETC2BCn (DXT)PVRTCBasis Universal (in KTX2)
Color Depth 8-bit, 16-bit, 32-bit (Integer/Float)
Developed by Khronos Group
Released 2010
Magic Bytes
AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A
Full KTX reference →

Browser Support Comparison

Browser IEF KTX
Chrome Chrome
✕ ✕
Firefox Firefox
✕ ✕
Safari Safari
✕ ✕
Edge Edge
✕ ✕
IE IE (Legacy)
✕ ✕
IEF

IEF Strengths

  • Provided a standard method for exchanging bi-level fax images during the early days of the Internet
  • Supported multi-page documents
  • Leveraged the highly resilient and well-documented TIFF container
Limitations
  • Completely obsolete and unsupported in modern computing environments
  • Strictly limited to 1-bit monochrome data, lacking color or grayscale capabilities
  • Magic bytes overlap completely with standard TIFF, making specific filetype detection difficult without parsing internal tags
KTX

KTX Strengths

  • Enables direct-to-GPU texture uploading, drastically reducing load times and CPU overhead in 3D applications
  • Supports complex texture types natively (mipmaps, cubemaps, 3D volumes, texture arrays)
  • Standardized across major Khronos APIs (OpenGL, Vulkan, WebGL) unlike vendor-specific formats like DDS
Limitations
  • Requires custom JavaScript loaders to parse and display on the web
  • Zero native support in consumer image viewers or 2D photo editing software
  • Format fragmentation: a KTX file containing an ASTC payload will fail to render on hardware that only supports BCn compression (KTX2 and Basis Universal solve this)

When to choose which format

IEF
Use IEF when…
  • Legacy Fax Transmissions
  • Early Internet Gateways
  • Archival
KTX
Use KTX when…
  • Real-time 3D Graphics
  • WebGL / WebGPU Applications
  • Mobile Games
  • Virtual/Augmented Reality (VR/AR)

More comparisons

IEF vs ACES → KTX vs ACES → IEF vs APNG → KTX vs APNG → IEF vs AVCI → KTX vs AVCI → IEF vs AVCS → KTX vs AVCS → IEF vs AVIF → KTX vs AVIF → All comparisons →
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