KTX

Khronos Texture

image/ktx Released 2010 · by Khronos Group

Khronos Texture (KTX) is a lightweight container format designed to store texture data for real-time 3D graphics applications using OpenGL, OpenGL ES, and Vulkan. It supports 1D, 2D, 3D, cubemap, and array textures, and can encapsulate pre-compressed GPU texture formats (like ASTC, ETC2, and BCn) for immediate, zero-copy uploading to the graphics pipeline.

3D & Textures Transparency ✦ HDR Production Ready

Technical Specifications

MIME Type

image/ktx

Extensions

.ktx

Container

KTX (Khronos Texture 1.1)

Compression

Uncompressed & GPU Compressed (ASTC, ETC, BCn, PVRTC)

Algorithms

ASTCETC1 / ETC2BCn (DXT)PVRTCBasis Universal (in KTX2)

Color Depth

8-bit, 16-bit, 32-bit (Integer/Float)

Metadata

None

Capabilities

Transparency

Animation

Progressive Loading

Alpha Channel

HDR Support

Official Specification

Aliases: image/x-ktx

Magic Bytes & HTTP Headers

File Signature (Magic Bytes)

AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A

ASCII: «KTX 11»\r\n\x1A\n

HTTP Headers

Content-Type: image/ktx

HTML Accept Attribute

accept="image/ktx, .ktx"

Browser Support Matrix

Browser	Status	Min Version
Chrome	Not Supported	—
Firefox	Not Supported	—
Safari	Not Supported	—
Edge	Not Supported	—
Internet Explorer	Not Supported	Legacy

Advantages & Limitations

Advantages

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)

Developer Code Snippets

import magic
print(magic.from_file('texture.ktx', mime=True)) # May output 'image/ktx' or 'image/x-ktx'

const FileType = require('file-type');
const type = await FileType.fromFile('texture.ktx');
console.log(type?.mime); // Outputs 'image/ktx'

import "net/http"
// Requires checking the specific 12-byte prefix: bytes.HasPrefix(buf, []byte{0xAB, 0x4B, 0x54, 0x58, 0x20, 0x31, 0x31, 0xBB, 0x0D, 0x0A, 0x1A, 0x0A})

$mime = mime_content_type('texture.ktx');
echo $mime; // Standard systems may map this to application/octet-stream

File Detection Steps

How to programmatically detect a image/ktx file by reading its raw bytes:

1 Check the first 12 bytes for the KTX signature (AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A)
2 Parse the 64-byte header to determine endianness, glType, glFormat, and pixel dimensions

Software Support

T

Three.js (with KTXLoader)

B

Babylon.js

C

Compressonator (AMD)

P

PVRTexTool (PowerVR)

ImageMagick

Conversion Tools

Share & Embed

Markdown Badge

[![KTX Format](https://freewebptojpg.com/mime/image/ktx/badge.svg)](https://freewebptojpg.com/mime/image/ktx)

Interactive iframe Widget

<iframe src="https://freewebptojpg.com/mime/image/ktx/embed" width="100%" height="280" style="border:1px solid #cbd5e1;border-radius:8px;" title="KTX Specs"></iframe>

JSON API

All data on this page is available as a free, open JSON API. Use it in your project, documentation, or tooling.

GET https://freewebptojpg.com/mime/image/ktx.json Open JSON

Free to use

No auth required

CORS enabled

Use from any domain

Cached 24h

Cache-Control headers set

Frequently Asked Questions

What is the difference between KTX and standard image formats like PNG or JPEG?

Standard images require the CPU to decompress them into raw pixels before they can be uploaded to the GPU, causing loading hitches and high memory usage. KTX files store pre-compressed GPU formats (like ASTC or BCn) that are uploaded directly to the GPU without CPU decoding, significantly reducing memory footprint and load times.

What is the magic byte for a KTX file?

KTX 1.1 files begin with a 12-byte identifier: AB 4B 54 58 20 31 31 BB 0D 0A 1A 0A. This roughly translates to '«KTX 11»' followed by carriage return, line feed, substitute, and line feed characters.

Can I use KTX textures in a web browser?

Native HTML <img> tags do not support KTX. However, they are heavily used in WebGL and WebGPU applications via JavaScript 3D engines (like Three.js or Babylon.js) which parse the KTX container and feed the compressed texture data directly to the graphics API.