ktx2-encoder

A lightweight JavaScript library for converting images to KTX2 (.ktx2) format. Powered by BinomialLLC/basis_universal.

Features

• Convert images to KTX2 format
• Support for both 2D images and cubemaps
• Integration with gltf-transform
• Support both Browser and Node.js
• Optional multithreaded encoding in cross-origin isolated browsers

Quick Start

Install:

npm install --save ktx2-encoder

Import and encode an image:

import { encodeToKTX2 } from "ktx2-encoder";

const source = new Uint8Array(await file.arrayBuffer());
const ktx2Data = await encodeToKTX2(source, {
  isUASTC: true,
  generateMipmap: true
});

In browsers, encodeToKTX2 also accepts exactly six Uint8Array images to encode a cubemap, ordered as [posx, negx, posy, negy, posz, negz].

To speed up encoding of large textures in a cross-origin isolated page, opt into multithreading with useThreads: true. See Multithreaded Encoding.

See the API guide for more details.

For gltf-transform

For users of glTF Transform, use the provided ktx2 transform. In Node.js, pass an imageDecoder; browser builds provide one automatically.

import { ktx2 } from "ktx2-encoder/gltf-transform";
import sharp from "sharp";

const imageDecoder = async (buffer: Uint8Array) => {
  const { data, info } = await sharp(buffer).ensureAlpha().raw().toBuffer({ resolveWithObject: true });
  return { data: new Uint8Array(data), width: info.width, height: info.height };
};

await document.transform(
  ktx2({
    isUASTC: true,
    enableDebug: false,
    generateMipmap: true,
    imageDecoder
  })
);

The browser build loads its bundled, version-matched basis_encoder.wasm automatically, with no CDN fallback. To serve a matching WASM file from a custom location, set wasmUrl explicitly. See the advanced guide.

Tool

Open the page of ktx2 encoder tool, you can use it to encode your image to ktx2.