wasm-vips

wasm-vips

libvips for the browser and Node.js, compiled to WebAssembly with Emscripten.

Programs that use wasm-vips don't manipulate images directly, instead they create pipelines of image processing operations building on a source image. When the end of the pipe is connected to a destination, the whole pipeline executes at once, streaming the image in parallel from source to destination a section at a time. Because wasm-vips is parallel, it's quick, and because it doesn't need to keep entire images in memory, it's light.

[!NOTE] This library is still under early development. See: #1.

Engine support

An engine that supports WebAssembly SIMD. This is present on most major browser engines and is part of Baseline 2023.

For V8-based engines, at least version 9.1.54 is required to match the final SIMD opcodes, this corresponds to Chrome 91, Node.js 16.4.0 and Deno 1.9.0.

For Spidermonkey-based engines, the JavaScript engine used in Mozilla Firefox and whose version numbers are aligned, at least version 89 is required.

For JavaScriptCore-based engines, the built-in JavaScript engine for WebKit, at least version 615.1.17 is required. This corresponds to Safari 16.4.

Chrome	Firefox	Safari	Edge	Node.js	Deno
:heavy_check_mark: version 91+	:heavy_check_mark: version 89+	:heavy_check_mark: version 16.4+	:heavy_check_mark: version 91+	:heavy_check_mark: version 16.4+	:heavy_check_mark: version 1.9+

Installation

wasm-vips can be installed with your favorite package manager.

npm install wasm-vips

yarn add wasm-vips

Usage

Browser

Requires vips.js (or vips-es6.js) and vips.wasm to be served from the same directory.

Since wasm-vips requires the SharedArrayBuffer API, the website needs to opt-in to a cross-origin isolated state, by serving the following HTTP headers on both the main document and vips*.js script:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

^{See https://web.dev/coop-coep/ for more information.}

After that, wasm-vips can be imported and initialized like this:

<script src="vips.js"></script>
<script type="module">
  const vips = await Vips();
</script>

Or, if you prefer to use ES6 modules:

<script type="module">
  import Vips from './vips-es6.js';
  const vips = await Vips();
</script>

^{This requires support for ES6 modules in workers.}

Node.js

On Node.js, wasm-vips is published as a dual-package, so it can be imported as both CommonJS and ES6 module:

// ES6 module
import Vips from 'wasm-vips';

// CommonJS module
const Vips = require('wasm-vips');

Then, wasm-vips can be initialized like this:

// Usage with top-level await
const vips = await Vips();

// Usage with .then
Vips().then(vips => {
  // Code here
});

Deno

On Deno, wasm-vips can be imported by using the npm: specifier:

import Vips from 'npm:wasm-vips';

const vips = await Vips();

Example

// Load an image from a file
using im = vips.Image.newFromFile('owl.jpg');

// Put im at position (100, 100) in a 3000 x 3000 pixel image,
// make the other pixels in the image by mirroring im up / down /
// left / right, see
// https://www.libvips.org/API/current/method.Image.embed.html
using embed = im.embed(100, 100, 3000, 3000, {
  extend: 'mirror'
});

// Multiply the green (middle) band by 2, leave the other two alone
using multiply = embed.multiply([1, 2, 1]);

// Make an image from an array constant, convolve with it
using mask = vips.Image.newFromArray([
  [-1, -1, -1],
  [-1, 16, -1],
  [-1, -1, -1]
], 8.0);

using convolve = multiply.conv(mask, {
  precision: 'integer'
});

// Finally, write the result to a buffer
const outBuffer = convolve.writeToBuffer('.jpg');

^{If not transpiling, this requires support for the using keyword. On Node.js, you can enable it with the --js-explicit-resource-management CLI flag.}